动物生态学：生态学 课件

A1 什么是生态学要 点生态学是研究有机体与其环境相互作用的科学。
“环境”是物理环境（温度、可利用水等）和生物环境（对有机体的、来自其他有机体的任何影响）
的结合体。
生态学的定义
A1 WHAT IS ECOLOGY?
Key Notes
A definition of
ecology
Ecology is the study of the interactions between
organisms and their environment,The?environment‘ is a
combination of the physical environment (temperature,
water availability,etc.) and any influences on an
organism exerted by other organisms-the biotic
environment.
个休,种群,群落和生态系统生态学所研究的有 4个可辨别尺度的亚部分,(i)探讨个体对其环境的反应； (ii)研究单个物种的种群对于环境的反应，和探讨诸如多度 (abundance)及其波动等的过程；（ iii）群落（出现在确定面积中的种群集合）的组成和结构； (iv)生态系统（群落与环境的非生物成分的结合）内的各种过程，例如能流、食物网和营养物的循环等。
Individuals,
populations,
communities and
ecosystems
There are four identifiable subdivisions of scale which
ecologists investigate;
(i) considering the response of individuals to their
environments;
(ii) Examining the response of populations of a single
species to the environment,and considering processes such
as abundance and fluctuations;
(iii) The composition and structure of communities (the
populations occurring in a defined area); (iv)the processes
occurring within ecosystems (the combination of a
community and the abiotic components of the environment),
such as energy flow,food webs and the cycling of nutrients.
A2 生态学的 10个规律要 点这些规律是什么？ 生态学的授课实践使得本书作者能够觉察到大学生学习生态学时常常陷入的某些一般性错误。本目录是为克服这些错误而设计的，既不全面，也不互相排斥，
但是我们希望它将作为有用的指南。
规律 1：生态学是科学生态学是一门纯科学学科，目标是了解有机体与其广阔环境的相互关系。分清楚科学观点与生态学知识的政治和社会影响这一件事是十分重要的。
A2 TEN RULES IN ECOLOGY?
Key Notes
What are these rules? The authors‘ experience of teaching ecology has given them experience of some common pitfalls which ecology students
often make,This list,designed to counter these pitfalls,is
neither comprehensive nor mutually exclusive,but we hope
will nevertheless serve as a useful guide to protocol,
Rule 1 Ecology is a science.
Ecology is a purely scientific discipline which aims to
understand the relationships between organisms and their wider
environment,It is important to segregate political and social
impacts of ecological understanding from the scientific
viewpoint.
规律 2：生态学只有按照进化论才可理解有机体巨大的多样性，以及其形态学、生理学和行为的变异的丰富性，全都是亿万年进化的结果。这个进化历史对于每一个个体都留下了不能去除的影响。我们今天发现的种种模式，只有按照进化论的观点才可能有意义。
规律 3：“对动物种有利”现象并不存在对于那些看起来对个体是花费的有机体行为模式，认为其出现是由于“对物种有利”的这种想法是一个非常普遍的误解。这是绝对和完全错误的。自然选择将会有利于那些传给大多数后裔的基因，即使这些基因有可能导致物种种群大小的下降。
Rule 2 Ecology is only understandable in the light of evolution.
The huge diversity of organisms,and the wealth of variety in
their morphologies,physiologies and behavior are all the
result of many millions of years of evolution,Thos
evolutionary history has left an indelible impression on each
and every individual,It is only possible to make sense of the
patterns we find today in the light of this evolutionary legacy.
Rule 3 Nothing happens’ for the good of the species’.
A very common misconception is the idea that patterns of
behavior in organisms which appear to be costly to an
individual occur‘ for the good of the species‘,This is
absolutely and completely wrong,Natural selection will
favor those genes which are passed on to the most offspring,
even if these genes may cause a reduction in the
species‘population size.
规律 4：基因和环境都很重要有机体自己所处的环境，对于它在开放的各种选择中决定取舍上，具有重要的作用。决定有权体构造的基因，同样具有根本的重要性。这两方面因素的基本性质及其相互作用，对于理解生态学都是很重要的。
规律 5：理解复杂性要求模型生态学是一复杂的对象，几乎每一个尺度都有大量变异 ——亿万个种，每种有大量基因变异，在复杂和动态的环境中有变化着的数量和随时间而改变的行为。
为了理解它，必需清楚的认明特异问题，然后形成可以检验的假设。以数学的思想方法构造假说常常是很有用的，可以躲开在语言模型中不能避免的含糊不清和混淆。数学模型在生态学里被广泛的应用。
Rule 4 Genes and environment are both important,
The environment an organism finds itself in plays an
important role in determining the options open to that
individual,The genes which define an organism‘s makeup
are also of fundamental importance,To understand ecology
it is important to appreciate the fundamental nature of both
of these factors and the fact that they interact.
Rule 5 Understanding complexity requires models.
Ecology is a complex subject,with huge variation at
almost every scale-millions of species,each with
considerable genetic variation,varying numbers and
ever-changing behaviors in a complex and dynamic
environment,To understand it,it is necessary to clearly
identify specific questions and then formulate hypotheses
which can be tested,It is often very useful to frame the
hypothesis in mathematical terms to avoid ambiguity and
confusion which are often inevitable in a verbal model,
Mathematical models are widely used in ecology.
规律 6：“讲故事”是危险的在打算解释生态学种种模式或相互关系的时候，人们很容易滑到虚假世界之中，每一个观察都很容易的被某特设的断言（所谓的“讲故事”）所解释了。无论如何，总想去推进假设实际上是应该避免的。
规律 7：要有分层次的解释对于任何观察，常常可以识别出一个直接的原因，但这种因果解释往往是资料不足的，我们需要进一步探索，以达到更完全的抓住情况。即使是现象已经被
“解释”了，更进一步和更深入的解释也是很好的，
它允许我们看见更完全的情景。
Rule 6 ‘Story-telling’ is dangerous.
In attempting to explain ecological patterns or
relationships,it is easy to slip into a make-believe
world where every observation is readily explained by
some ad hoc assertion –?story-telling‘,The temptation
to advance hypotheses as facts should be avoided at all
costs.
Rule 7 There are hierarchies of explanations.
For any observation there is often an immediate cause
that can be diagnosed,Often this causal explanation is
insufficiently informative and we need to probe deeper
to reach a fuller grasp of the situation,Even if a
phenomenon is?explained‘ there may well be further
and deeper explanations which allow us to see the
fuller picture.
规律 8：有机体具有很多限制有机体表现出来的形态、功能和环境适应力的总多样性是令人惊叹的，每个个体（和每一个种，但较少程度）则在相对较小的约束范围中运转。约束基本上有两类：（ i）物理的，（ ii）进化的。由于这些约束，进化从来就没有达到“完善”过，有机体基本上是许多妥协的杂烩。
Rule 8 There are multiple constraints on organisms.
Whilst the total diversity of form,function and
environmental resilience exhibited by organisms is awe-
inspiring,each individual (and,to a slightly lesser
extent,each species) operates within a relatively narrow
range of constraints,Constraints fundamentally take
two forms,(i) physical and (ii) evolutionary,Evolution
cab never reach?perfection‘ because of these
constraints and organisms are essentially hotchpotches
of numerous compromises,
规律 9：机会是重要的随机事件在生态学中起关键性的作用。林冠中出现林窗或沙丘在风暴后裂口，对于当地动植物区系将有重要的影响，但是，林窗和裂口出现的时间和地点都是不可预测的。机会的作用也与有机体过去进化综合在一起。生态学中机会事件的重要性并不意味着生态学中的模式是完全不可预测的，但是它必然是位于预言细节的潜在水平之边缘。
规律 10：在生态学家心目中的生态学边界生态学是一门广泛的科学，覆盖着生物和物理环境，
从而作为潜在相关的，很少有被排除在外的了。数学、
化学和物理学都是理解生态学的基本工具。
Rule 9 Chance is important.
Chance events play a critical role in ecology,The
opening of a gap in a forest canopy or the breaching of
a sand dunce after a storm will have a major impact on
the ecology of the local fauna and flora,but both are
unpredictable in either time or location,The
importance of chance events in ecology does not mean
ecological patterns are wholly unpredictable,but it
necessarily places boundaries on the potential level of
predictive detail.
Rule 10 There boundaries of ecology are in the mind of the ecologist.
Ecology is a broad science,covering both organisms
and physical environments and hence excludes little as
potentially relevant,Mathematics,chemistry and
physics are tools essential to the understanding of
ecology.
B1 适 应适 合 度 适合度是个体生产能存活后代、并能对未来世代有贡献的能力的指标。个体的相对适合度是有变化的，这种变化部分决定于个体的遗传区别，部分决定于环境的影响。
自然选择 种中具有最高适合度的个体将会对未来世代作出特别高的贡献。如果适合度的差别含有遗传的成分，则后代的遗传组成会有改变。这个过程称为自然选择或
“最适者生存”。
要 点
B1 ADAPTATION
Key Notes
Fitness is measure of the ability of an individual to produce
viable offspring and contribute to future generations,
Individuals vary in their relative fitness,and this variation is
due partly to genetic differences among individuals and
partly to environmental influences.
The individuals in a species which have the highest fitness will
contribute disproportionately to the subsequent generations,If
fitness differences have a genetic component,then the genetic
make-up of the subsequent generations will be altered,This
process is known as natural selection or?survival of the fittest‘.
Fitness
Natural selection
适 应 有机体所具有的有助于生存和生殖的任何可遗传特征都是适应。适应性特征可以是生理的或行为的。适应是自然选择的结果。
基因型和表型 基因型是个体的遗传组成。表型是各个有机体，它是基因型与环境的相互作用的产物。由于环境对基因型的影响，表型发生变化的能力叫做 表型可塑性 （如人的晒黑、风造形的植物、蝗虫的单生或群居型）。
相关主题 生态学的 10个规律（ A2） 物种形成（ 02）
遗传变异（ 01）
Any heritable trait possessed by an organism which aids
survival or reproduction is an adaptation,Such traits may
be physiological,morphological or behavioral,Adaptation
is the result of natural selection.
The genotype is the genetic composition of an individual,
The phenotype is the individual organism,a product of the
interaction between its genotype environmental influences
on its genotype is known as phenotypic plasticity (e.g,
human suntan,wind-shaped plants locust morph (solitary
or migratory)).
Related topics Ten rules in ecology (A2) Speciation (O2)
Genetic Variation (O1)
Adaptation
Genotype and
phenotype
B2 应付环境变异要 点条 件 引起有机体对其反应的,可变的环境因子是条件
(conditions),例如温度,酸度和盐度 。 条件是不可能被减少的 ——它 不 能 被 有 机 体 用 掉 或 消 耗 掉 。
资 源 有机体消耗的任何东西，对该有机体而言，就是资源。
例如，蜜是蜜蜂的资源，光是一切绿色植物的资源。
Key Notes
Variable environmental factors which organisms respond to
are conditions,Examples include temperature,acidity and
salinity,Conditions are not depletable – they are not used up
or consumed by an organism.
Anything which the organism uses up or depletes is a
resource for that organism,Thus,nectar is a resource for
honey bees,and light is a resource for all green plants.
B2 COPING WITH ENVIRONMENTAL
VARIATION
Conditions
Resources
环境变异 大多数有机体都必须应付在一定时间尺度范围内不断变化着的外界环境。某些环境因子的变化以秒或分计
（如当有云块时的阳光强度），另一些因子的变化以日或季计，甚至更长更长的时期（如冰河周期）。
内 调 节 生物细胞不可能在剧烈的变动环境中运行，因此，有机体要采取 行动以限制其内环境的变异性。
Most organisms have to cope with a continually changing
external environment over a range of timescales,Some
environmental factors may change over seconds or
minutes (e.g,sunlight intensity when,there is patchy cloud)
whilst others may change daily or seasonally or over a
much change daily or seasonally or over a much longer
period (e.g,glaciation cycles).
Environmental
variation
Biological cells cannot function with a wildly
fluctuating environment and organisms therefore take
steps to limit their internal variation.
Internal
regulation
稳 态 有机体在可变动的外部环境中维持一个相对恒定的内部环境，称为稳态（ homeostasis）。一切有机体都采取一定程度的稳态控制，但是一般地说，大型有机体比小型的更易从其外部环境中退耦（ decouple）。
负 反 馈 大多数生物的稳态机制以大致一样的方式起作用：如果一个因子的内部水平（如温度或渗透性）太高，该机制将减少它；如果水平太低，就提高它。这个过程叫做负反馈。负反馈反应的方向与信号的相反。
The maintenance of a relatively constant internal
environment by an organism in a variable external
environment is called homeostasis,All organisms adopt
a degree of homeostatic control,but,as t rule,large
organisms are more decoupled from their external
environment than small ones.
Most biological homeostatic mechanisms act in a
broadly similar way,if the current internal level of a
factor(e.g.temperature or osmolarity) is too high,the
mechanism will reduce it; if the level is too low the
mechanism will increase it,This process,by which the
response is opposite to the signal,is known as negative
feedback.
Homeostasis
Negative feedback
耐 受 性 有机体能够应付其外部环境的变化（虽然不同物质表现很不相同）。种的成员能够生存的环境条件上限和下限是种的耐受限度。在此极端条件下通常不出现生长，但在条件更狭窄的范围内能生长，而适合度最大只能出现在更窄的最适范围内。
相关主题 植物与水（见 D2） 对温度的响应（见 E2）
动物与水（见 D3） 太阳辐射与植物（见 F1）
Organisms can cope with variation in their external
environment (though different species may differ markedly),
The upper and lower extremes of species limits of tolerance,
Usually,growth will not occur at these extremes but in a
narrower range of conditions,and fitness will be greatest
only for a yet narrower optimal range.
Plants and water (D2) responses to
temperature (E2)
Animals and water (D3) solar radiation and
plants (F1)
Related topics
tolerance
B3 生 态 位要 点有机体的生态位（ niche）是它在它的环境中所处的位置，包括它发现的各种条件、所利用的资源和在那里的时间。
有机体的栖息地（ habitat，或译生境）是它所处的物理环境，例如，温带阔叶林。每一个栖息地提供许多生态位。
定义有机体生态位的每一个条件和资源，对于有机体能出现的空间提供一个维度。一起考虑所有维度，全面确定的有机体的生态位，是多维生态位空间，或,n-
维超体积”。
生 态 位栖 息 地多维生态位空间
The ecological niche of an organism is the position it
fills in its environment,comprising the conditions
under which it is found,the resources it utilizes and
the time it occurs there.
Key Notes
The habitat of an organism is the physical
environment it is found in,for example,a temperate
broad-leaved woodland,Each habitat provides.
Each condition or resource which defines the niche
of an organism contributes one dimension to the
space in which the organism‘s niche,and is the
multidimensional niche space,or‘n-dimensional
hypervolume‘.
B3 THE NICHE
Niche
Habitat
Multidimensional
niche space
基础生态位 在没竞争和捕食条件下，有机体的生态位空间叫做基础生态位（ fundamental niche）。
相关主题 竞争的性质（见 I1） 资源分配（见 I3）
种内竞争（见 I2）
实际生态位 当有竞争和捕食出现时，有机体所占有的生态位空间是实际生态位（ realized niche），实际生态位始终是基础生态位的一个子集。
The niche space an organism can fill in the absence of
competition or predation is known as the fundamental
niche.
The niche space occupied by an organism when
competition and predation occur is the realized niche,
which is always a subset of the fundamental niche.
The nature of competition (11) Resource
partitioning(13)
Intraspecific competition (12)
Fundamental niche
Realized niche
Related topics
C1 太阳辐射与气候要 点太阳辐射 太阳能使地球上的气候产生变化。太阳的能量到达地球上时，高能量的光波被地球吸收，并以热辐射的形式再释放出来。被加热的空气上升，与此同时膨胀。此膨胀吸收了空气中的能量，导致空气温度下降，这个过程称为绝热冷却。
Key Notes
Solar energy drives climatic processes,Energy from the
sun strikes the Earth where high-energy wavelengths of
light are absorbed and re-emitted in the form of radiant
heat,Warmed air rises,and expands as it does so,This
expansion takes energy from the air,resulting in
temperature reduction,a process known as adiabatic
cooling.
C1 SOLAR RADIATION AND CLIMTE
Solar radiation
地球的风型 地球上主要的风系是由环绕赤道的热空气的上升运动而引起的，从南北而来的较冷空气替代了热空气，形成了信风。科里奥利（ coriolus）效应（由地球的自转引起）
使移动的空气在北半球向右偏转，在南半球向左偏转。
南北两半球的信风恰好在赤道北部于热带辐合区（ ITCZ）
相遇。在南北纬 40° 地区的高层大气中，发生从西而来的“急流”风。地球两极的冰群增加了地球表面的反射系数和（或反照率），降低了空气的升温，产生了一些密集的冷空气带。
The major wind systems of the Earth result from the
upward movement of warm air around the equator,which is
replaced by cooler air coming form the mouth and south,
forming the trade winds,The Coriolus effect (caused by the
Earth‘s rotation) deflects moving air to the right in the
Northern Hemisphere and to the left in the Southern
Hemisphere,The trade winds meet just to the north of the
equator in the intertropical convergence zone (ITCZ),At 40。
North and southwesterly,upper atmosphere?jet stream‘
winds occur,Ice packs at the poles increase the surface
reflectance (or?albedo‘) which reduces the heating of the
air,resulting in zones of dense cold air.
Global wind
patterns
洋 流 风搅动着地球上的海洋，信风将海水掀起海浪冲向大陆，造成海平面的不平衡。例如，北美洲的海平面在大西洋一侧比太平洋一侧高一两米，这种差异形成了洋流。因此，如在加勒比海堆聚的温暖海水，沿着美洲海岸向北移动，即墨西哥湾流，然后转向欧洲北部，
对欧洲具有显著的增温作用。
降 雨 潮湿的空气遇冷形成降雨。温暖的空气比冷空气携带更多的水，所以冷即使热空气凝结成小水滴，并以雨的形式降落。例如，如果空气在海上流过，然后沿山上升，这空气将以绝热温度递减率冷却，即每上升
1000m温度下降 6~10℃,这还取决于空气中的含水量，
并将导致降雨。空气翻越过山后，将下降并被压缩变暖，导致在山的背风面形成雨影。
The world‘s oceans are stirred by winds,Trade winds pile up water
against continents,causing an imbalance in sea levels,For example,in
North America sea levels are 1or 2 m higher on the Atlantic side than
the Pacific side,This difference drives oceanic currents,thus,for
instance,warm water piled up in the Caribbean moves northwards
along the American coast as the Gulf Stream and then veers towards
northern Europe,where it provides a strong warming influence,
Rain falls when moist air cools,Warm air can hold more water than
cool air,so cooling causes water droplets to condense and fall as rain,
If,for example,air travels over sea and then rises over a mountain,the
air will cool at the adiabatic lapse rate,which is 6-10℃ km-1,
de[ending on water content,and rainfall will result,After crossing the
mountains,the air will descend and warm as it is compressed,leading
to a rain shadow on the lee side of a mountain.
The circulation of
oceans
Rain
灾 害 热带海洋的静止状态可导致风暴。在数天内，温暖海水上方空气的极微小运动，可能被突然升起的一些暖空气柱扰乱，引起海水表面的风卷进不断升起的空气柱中。上升的空气饱含了水分，在上升过程中，空气膨胀并冷却。水蒸汽转变为水滴，释放凝结热，并提供能量进一步推动此过程，这就可能发展成飓风。
相关主题 微气候（ C2） 生态系统格局（ S1）
Static conditions in tropical oceans can lead o storms,
Minimal movement of air over warm water over a period of
days can be disrupted by columns of warm air suddenly
rising,resulting in surface winds being sucked into the rising
column,The rising air is saturated with water and as it rises
the air expands and cools,The water vapor turns into
droplets,which release their heat of condensation and
provide energy go further fuel the process,which may
develop into a hurricane.
Microclimate (C2) Ecosystem patterns(S1)Related topics
Havoc
C2 微 气 候要 点全球的温度与降雨图掩盖了局部地区的变化。然而，
即使在很小的尺度范围内，也有大量的微气候变化。
微气候是动植物生活在其中的气候。
气候的局部变化
Key Notes
Global maps of temperature and rain obscure local variation,
However,on an even smaller scale there is a great deal of
microclimatic variation,The microclimate is the climate in
which plants and animals live.
C2 MICROCLIMATE
Local variations
in climate
在温带生态系统中，热的主要储存位置是土壤，白天土壤储存热，夜间作为热量的来源。土壤的热传导
（热流标准率测量）决定了热转换速度。物体经历的温度变化是热传导的结果，将随着它的热容量而改变。
物质的热容量是 1cm3 物质上升 1℃ 所需要的热量。
热
A major storage location for heat in temperate
ecosystems is the soil,which acts as a sink during the
day and a source at night,Thermal conductivity (a
measure of the standardized rate of heat flow) of soils
determines the rate of heat transfer will vary with its heat
capacity,The heat capacity of a substance is the amount
of heat required to raise 1 cm3 by 1℃,
Heat
温度剖面 温度剖面是在地面上的空气中形成的。夜间，地面和庄稼表面迅速冷却，以致于表面变成温度剖面中最冷的部位。因此，形成温度倒置，空气的温度随着高度而增加。白天，地表面是温度剖面中最温暖的部位，
在这种状态下，空气的温度随高度而下降。
相关主题 太阳辐射与气候（ C1） 生态系统格局（ S1）
相对湿度 相对湿度是指空气的水蒸气含量，用在那个温度下饱和水含量的比率来表示。水蒸气来自陆地、水和植被的蒸发表面的蒸发。相对湿度的微气候变化甚至能够比所涉及到的温度变化更明显。白天，水蒸气的转运通常是向上的。
Temperature profiles develop in the air above the ground,
During the night ground and crop surfaces cool rapidly so
that the surface becomes the coldest location in the profile,
Thus,a temperature inversion develops in which air
temperature increases with elevation,During the day the
surface is the warmest location in the profile and under these
conditions air temperature decreases with elevation.
Relative humidity is the air water vapor content expressed as
a ratio to the saturated water content at that water content at
that water temperature,Water vapor is derived from the
evaporating,Microclimate variations in relative humidity
can be even more marked than those involving temperature,
The transport of water vapor is usually upward during the
day,
Relative humidity
Solar radiation and climate (C1) Ecosystem patterns (S1)Related topics
Temperature
profiles
D1 水的特性要 点水的化学特性 水是所有有机体普遍的内部介质，构成 90%以上的生命物质。水分子是由具有 105° 角的氢 -氧 -氢组成，其形状导致有氢的一边显正电荷（正电性的），而另一边显负电荷（负电性的）。这解释了与物理和化学反应有关的水的许多特性。它也解释了为什么水被吸附到带电的离子上。
光线穿透水 可见光穿过水体遵循一个称为“比尔定律”（ Beer‘s
law）的负指数关系。由于水激烈地吸收了红外线的辐射，太阳光谱的红外线部分随水深增加而急剧耗竭。
因此，由于县浮的固体（泥沙）引起的混浊，将急剧地使可见光衰竭。
Water is the universal internal medium of all organisms,comprising
more than 90% of living matter,The shape of the water molecule,
with an HOH angle of 105。 Results in the side with the hydrogen
being positively charged (electropositive) whereas the other side is
negatively charged (electronegative),This explains many of water‘s
properties relative to physical and chemical reactions,It also
explains why water is attracted to charged ions.
Key Notes
The penetration of visible light through water bodies follows a
negative exponential relationship called‘Beer‘s law‘,Since water
strongly absorbs infrared radiation,that portion of the solar spectrum
will be sharply depleted as water depth increases,Furthermore,
turbidity due to suspended solids (silt) will strongly deplete visible
light.
D1 THE PROPERTIES OF WATER
Chemical
properties of water
Penetration of light
through water
水和温度 水的两个特性使它特别适合于作为许多生物栖息的一种介质。（ i）水有高的热容量，（ ii） 4℃ 时水的密度最大。高热容量意味着它能吸收热能，而只增加很少的温度。其结果使水生生物减少了受温度波动的影响。
在较低温度时，水的密度增加，因而也更重，最大的密度发生在 4℃ 。因此，冰浮在水上，水体从上向下冻结。这种现象保护了水生生物，因为冰作为一种绝热体，阻止下层水的温度进一步降低。
Two features of water make it particularly suitable as a medium for
life-forms to inhabit,Water has (i) a high heat capacity and (ii)
maximal density at ℃,A high heat capacity means that it can
absorb heat energy with only a small increase in temperature,As a
result,aquatic life forms are buffered from temperature fluctuations,
Water becomes increasingly dense and therefore heavier at lower
temperatures,with the maximum density occurring at ℃,Thus,ice
floats on water and a body of water freezes from the top down,This
phenomenon protects aquatic organisms because ice acts as an
insulator to prevent further decreases in temperature in the
underlying water,
Water and
temperature
相关主题 植物与水（ D2） 动物与水（ D3）
能量转换和水相在陆地温度中，水很容易从蒸汽转化成液相和固相，
同时释放或吸收大量的热。例如,1g水蒸发，大约需要 2430J的热量，即汽化潜在热。水蒸气进入空气中直到冷凝，释放出热量 2430J/g。当水结冰时，大约 335J/g
被释放作为熔合热，而雪融化时也需要相同数量的能量。因此，在水的相变化中这些能量的消耗和释放过程，提供了从地球表面和到地球表面的大量热的转化机制。
At terrestrial temperatures,water passes easily from vapor
to liquid and solid phases with a large release or absorption
of heat,For example,the evaporation of 1 g of water
requires about 2430 J of heat,the latent heat of vaporization,
The vapor is carried in air until the water condenses,
releasing 2430 J g-1,When water freezes,about 335 J g-1 is
released as the heat of fusion and the same amount of
energy is required to melt the snow,Thus,these energy-
consuming and releasing processes in water phase changes
provide the mechanisms for the transportation of large
quantities of heat to and from the surface of the earth.
Related topics Plants and water (D2) Animals and water (D3)
Energy transfer
and water phases
D2 植物与水要 点土 壤 水 对于陆地植物，水的主要来源是土壤，它起了蓄水池的作用。当下雨或雪融化时，水进入蓄水池，并流进孔隙。土壤的水容量上限称为田间持水量（ field cap-
acity）。这是土壤孔隙抗地心引力所储蓄的水量。植物不能吸取土壤中储蓄的全部水，因为它们不能产生足够的吸力从更细的土壤孔隙中吸水。因此可利用水的下限是由植物物种的生理特性所决定的，被称为 永久萎蔫点 （ permanent wilting point） ——土壤水（ soil
water）含量在这个点上，植物枯死，不能恢复。
For terrestrial plants the main source of water is the soil,which
serves as a reservoir.,water enters the reservoir as rain or melting
snow and passes into the soil pores,The upper limit of the water-
holding capacity of a soil is called the field capacity,This is the
amount of water which can be held by soil pores against the force
of gravity,Plants cannot extract all the water held in the soil,as
they cannot exert sufficient suction force to extract water from the
narrower soil pores,The lower limit of water availability is thus
determined by the physiology of the plant species and is known as
the permanent wilting point – the soil water content at which plants
wilt and are unable to recover.
Key Notes
D2 PLANTS AND WATER
Soil water
根对水的吸收 根以两种方式从土壤中捕获水：要么水穿过土壤向根移动，要么根生长穿过土壤向水移动。当根以它的表面从土壤毛细管孔隙吸水时，在根的周围产生了水耗竭区。如果根从土壤中吸水很快，资源耗竭区（ RDZ）
将以一个低速率从周围土壤中接收水，从而限制了水的可利用性，使植物即使在含水丰富的土壤中也可能枯萎。
水生植物和水 在水环境中，水显然是随意可利用的。然而，内部体液的渗透压调节可能消耗能量，特别是在盐水环境中。
水环境的盐度与沿海陆地栖息地的盐度，对植物分布移度有重要的影响。生长在高盐度中的植物，即盐生植物，它们的液泡中累积了电解质，但在细胞质和细胞器官中保持着低浓度。
Roots can cap capture water from the soil in two ways,either water
may move through the soil towards a root or the root may grow
through the soil towards the water,As a root withdraws water from
the soil capillary pores at its surface,it creates water depletion zones
around it,If a root draws water from the soil very rapidly,the
resource depletion zone (EDZ) will receive water from the
surrounding soil at a slow rate,restricting water availability,so
plants may wilt even in soil containing abundant water.
The uptake of water
by roots
Water is apparently available in aquatic environments,However,the
osmotic regulation of internal fluids can be energetically expensive,
especially in saline environments,The salinity of an aquatic
environment and of terrestrial habitats bordering the sea has an
important influence on plant distribution and abundance,Plants
which grow in high salinity,halophytes,accumulate electrolytes in
their vacuoles,but the concentration in the cytoplasm and organelles
is kept low.
Aquatic plants and
water
水的可利用性与植物生产力降雨量是森林植物生产量的关键决定因子，而在干旱地区，初级生产量随降雨量的增加大致呈一个线形增长。假设一个地区没有土壤的水限制，并完全地被植物覆盖，水从这个地区的蒸发量就是 潜在蒸发蒸腾速度 （ potential evapotranspiration rate）。这个指标和降雨量之间的差异决定了环境是潮湿的，还是干旱的。
相关主题 水的特性（ D1） 对温度的响应（ E2）
动物与水（ D3） 温度与物种分布（ E3）
Precipitation is a key determinant of plant productivity in forests,
whilst in arid regions there is an approximately linear increase in
primary productivity with increasing precipitation,The amount of
water that would be transpired from a site,assuming no soil water
limitation and complete vegetation cover is the potential
evapotranspiration rate,The difference between this index and the
precipitation rate defines whether the environment is moist or arid,
Related topics The properties of water (D1) responses to temperature (E2)
Animals and water (D3) temperature and species distribution (E3)
Water availability
and plant
productivity
D3 动物与水要 点鱼类的水平衡 在水环境中保持水平衡是有疑问的，它是通过渗透调节机制解决的。淡水鱼必须连续地排泄过量的水，因为鱼与它的环境相比，它是高渗透性的（体液的溶质浓度比水的溶质浓度高），它们产生大量的低浓度的尿。生活在海水中的硬骨鱼有相反的问题，它们要的功能是去除两价的离子，如像 Ca 2+,Mg 2+ 和 SO 。2-4
Maintaining water balance is problematic in an aquatic
environment,which is countered by osmoregulatory
mechanisms,Freshwater fish have to continually excrete
excess water because the fish is hypertonic relative to its
surroundings (the concentration of solutes in body fluids
is higher than the solute concentration of the water),and
they produce a large volume of very dilute urine,Bony
fishes living in seawater have the opposite problem,
being hypotonic to their surroundings,The kidneys of
marine fish secrete very little urine,and instead function
mainly as a means of removal of divalent ions such as
Ca2+,Mg2+and SO42-.
Key Notes
Water balance in
fish
D3 ALNIMALS AND WATER
两栖类的水平衡两栖类的肾功能很像淡水鱼的肾功能。然而在陆地上，
脱水对渗透调节是最重要的问题，蛙保存体液是通过膀胱上皮细胞的重吸收水。
陆生动物的水保持陆生动物面对的主要问题是连续地失水，这是供应到组织表面维持潮湿所必需的水。当空气被吸入时，它沿着呼吸道进入肺，和潮湿的呼吸组织相接触。如果潮湿的空气被呼出，水就会丢失。大多数陆生动物呼吸湿度的维持包括了 逆流交换 （ countercurrent exchange）
从肺呼出的气体，在呼出的通道上有一个像逆流的梯度。呼出的气体和呼吸表面的相互作用，导致水分有效地返回组织。
Amphibian kidneys function much like those of
freshwater fishes.However,on land,where
dehydration is the most important problem in terms
of osmoregulation,frogs conserve body fluid by
reabsorbing water across the epithelium of the
urinary bladder.
Water balance in
amphibians
A major problem faced by terrestrial organisms is the loss of
a continuous supply of water necessary to keep tissue
surfaces moist.When air is inhaled,it passes along the
respiratory tract into the lungs,where it is in contact with the
moist respiratory tissues.If the moist air was exhaled,water
would be lost,The recovery of respiratory moisture by most
terrestrial animals involves countercurrent exchange,Exhaled air
from the lungs encounters a countercurrent-like gradient on
the way out,This interaction between the departing air and
the respiratory surfaces results in an efficient return of
moisture to the tissues,
Water conservation
by terrestrial
animals
哺乳动物肾脏的水保持哺乳动物肾脏的水保存能力表现出关键的陆生适应性。
尿离开肾脏之前，水在亨利氏袢中被回收。适应于荒漠的哺乳动物，如更格卢鼠，排泄高浓度的高渗尿，
它们有极长的亨利氏袢。相反，河狸大部分时间是在淡水中渡过的，它们的肾单位具有很短的袢，产生低浓度的尿。爬行动物的肾脏结构较简单，产生的尿最多也就是与体液等渗。这意味着，尿的溶质浓度与体液的溶质浓度是相等的。
相关主题 太阳辐射与气候（ C1） 植物与水（ D2）
微气候（ C2） 生态系统格局（ S1）
水的特性（ D1）
The water-conserving ability of the mammalian kidney
represents a key terrestrial adaptation,Water recovery from
the urine before it leaves the kidney takes place in the loop
of Henle,Mammals adapted to the desert (such as kangaroo
rats) that excrete highly concentrated hypertonic urine,have
exceptionally long loops of Henle,In contrast,beavers,
which spend much of their time in fresh water,have
nephrons with very‘short loops,resulting in dilute urine,The
kidneys of reptiles are less sophisticated and produce urine
that is,at best,isotonic to body fluids,This means that the
solute concentration of urine is equal to the solute
concentration of the body fluids.
Water conservation
by mammalian
kidneys
Related topics Solar radiation and climate(C1) Plants and water (D2)
Microclimate (C2) Ecosystem patters (S1)
The properties of water (D1)
E1 温度与代谢要 点恒温动物和变温动物按照有机体的体温调节过程有可能对有机体进行分类。
一种可能的划分是恒温动物和变温动物。当环境温度升高时，恒温动物保持着大致恒定的体温，而变温动物的体温随环境温度而改变。这种分类的一个问题是，
即使是典型的恒温动物也经历了降低体温的时期。在有机体之间，可供选择的另一种划分描述如下。
E1 TEMPERATURE AND
METABOLISM
It is possible to categorize organisms according to their
temperature regulation processes,One possible division
is between homeotherms and poikilotherms,As
environmental temperature rises,homeotherms maintain
an approximately constant body temperature,while the
body temperature of poikilotherms varies with
environmental temperature,One problem with this
classification is that even classic homeotherms
experience periods of reduced temperature.,an
alternative distinction between organisms is described
below.
Key Notes
Homeotherms and
poikilotherms
外温动物和内温动物像爬行动物等有机体属外温动物，它们很大程度地依赖于外来的热来提高自己的体温。内温动物是能够在体内产热以升高体温的有机体。鸟和哺乳动物属于这一类。 热中性区 （ thermoneutral zone）是环境的温度范围，在这个温度范围内，内温动物仅使用一个最小的代谢率以维持恒定的体温。环境温度离热中性区越远，
内温动物维持恒定体温消耗的能量越多。
热 交 换 所有的有机体从它们的环境中得到热，也将产生的热散失到它们的环境中。种种生理学和行为学的机理被用于调节体热。尽管有这些机理，外温性动物的体温还是明显地随环境条件而改变。
Ectotherms are organisms such as plants,reptiles and
protista which are largely reliant on external sources of
heat to raise their body temperature.endotherms are
organisms capable of generating heat internally in order to
raise their body temperature,Birds and mammals make up
this group,The thermoneutral zone is the range of
enmironmental temperatures in which an endotherm has
only to exert a minimum metabolic effort in order to
maintain a constant body temperature,The further away
from the thermoneutral zone that the environmental
temperature moves,the more energy the endotherm has to
expend to maintain body temperature,
Ectotherms and
endotherms
All organisms gain heat from and lose heat to their
environment as well as producing heat,A variety of
physiological and behavioral mechanisms are used to
regulate heat,Despite these mechanisms,the body
temperature of an ectotherm varies significantly with
environmental conditions.
Heat exchange
温 度 阈 高温可能导致酶失活或代谢组分不平衡，例如植物的呼吸作用快于光合作用而导致死亡。然而高温对外温动物最普遍的影响是引起脱水。所有陆生外温动物必须保持水，但在高温下失水率能够成为致死因子。不同物种对低温的耐受性有很大的差异，这与结冰、寒冷和坚硬的过程有关。温度低于 -1℃ 时很多物种被冻死，
这是由于细胞内冰晶形成的损伤效应；那些生活在整个冰冻冬天的种，经常是处于一种有抵抗力的休眠时期，这是它们生命周期中的一个阶段。
相关题目 太阳辐射与气候（ C1） 对温度的响应（ E2）
植物与水（ D2） 温度与物种分布（ E3）
动物与水（ D3） 生态系统格局（ S1）
High temperatures may lead to enzyme inactivation or the
unbalancing of components of metabolism; for example,in
plants,respiration may proceed faster than photosynthesis,
leading to death,however,the most frequent effect of high
temperature on ectotherms is dehydration,All terrestrial
ectotherms must conserve water but at high temperatures
rates of water loss can be lethal,There are large differences
between the low temperature tolerances of differing species,
associated with the processes of freezing,chilling and
hardening,Many are killed by temperatures below –1℃
due to the damaging effects of ice-crystal formation within
cells; those that live through freezing winters often do so at
a resistant,dormant stage of their life cycle.
Temperature
thresholds
Related topics Solar radiation and climate(C1) Responses to temperature
(E2)
Plants and water (D2) Temperature and species
Animals and water (D3) distribution (E3)
Ecosystem patterns (S1)
E2 对温度的响应要 点温度和酶反应速度酶催化反应的速度随温度而增加。在外温动物中这意味着在较高的温度中代谢活力更快。温度系数（ Q 10)
是温度升高 10℃ 对代谢速度影响的指数，经常大约为
2.0。
发育和生长的速度在非致死温度范围内，温度对外温动物最大的影响很可能是影响了发育和生长的速度。当用发育速度对体温做图时，存在着一个直线相关的温度范围。“生理时间”是将温度和时间相结合的一个测量，应用于外温动物，它反应了这些有机体的生长和发育依赖于温度及时间。
The rate of an enzyme catalyzed reaction increases with temperature,
In ectotherms this means that metabolic activity will be faster at
higher environmental temperatures,The temperature coefficient (Q10)
is an indexof the effect of a 10℃ temperature rise on metabolic rate,
and is often near 2.0,
Key Notes
Within the nonlethal temperature range the most important effect
on ectotherms of temperature is likely to be its effect on rate of
development and growth,When rate of development is plotted
against body temperature there exists an extended range of
temperatures over which the relationship is linear,?Physiological
time‘ is a measurement combining temperature and time and
applied to ectothermic organisms,which reflects that growth and
development of these organisms is dependent on environmental
temperature as well as time.
Temperature and
rates of enzyme
reaction
Rates of development
and growth
E2 RESPONSES TO TEMPERATURE
驯化和气候驯化温度能够作为一种刺激物起作用，决定有机体是否将开始发育。春化法是通过低温诱导开花。有机体在实验室里暴露到较高（或较低）的温度能够改变有机体的温度反应。有机体对实验环境条件变化产生的适应性反应称为 驯化 （ acclimation）。有机体对自然环境条件变化产生的生理适应性反应称为 气候驯化
（ acclimatization）。
相关主题 太阳辐射与气候（ C1） 温度与物种分布（ E3）
温度与代谢（ E1） 生态系统格局（ S1）
Temperature may also act as a stimulus,determining whether the
organisms will begin development,Vernalization is the induction
of flowering by low temperatures,Exposure of an organism to
higher (or lower) temperatuers in the laboratory can alter the
organisms temperature response,The habituation of an organism‘s
response to changes in laboratory environmental conditions is
termed acclimation,Acclimatization is the habituation of an
organism‘s physiological response to changes in natural
environmental conditions.
Acclimation and
acclimatization
Related topics Solar radiation and climate(C1) Responses to temperature (E2)
Plants and water (D2) Temperature and species
Temperature and metabolism (E1) distribution (E3)
Ecosystem patterns (S1)
The rate of photosynthesis is a gross measurement of the rate at
which a plant captures radiant energy and fixes it into carbon
compounds,Net assimilation is the difference between
photosynthetic assimilation and losses due to respiration,
Therefore,net assimilation will be negative in the dark and will
increase with increasing PAR,The intensity of PAR at which the
gain in photosynthesis equals the losses is known as the
compensation point.
Measurement of
photosynthesis
E3 温度与物种分布要 点物种分布与温度地球上主要生物群系的分布反应了主要的温度带。然而当考虑物种分布的时候，很难归结于温度的作用。
在某些情况下，一个物种的分布界限能够归结于阻止物种生存的致死温度。然而，种的分布限与等温线间相一致，是一种更广泛分布的相关类型。等温线是在地图上把具有相同平均温度的地方连结起来的线。总的说来，一个有机体的分布界限不是由致死温度所决定，而是由造成竞争强弱条件所决定。
The distribution of the major biomes over the Earth reflects the major
temperature zones,However,it is more difficult to attribute a role to
temperature when considering species distribution,In certain cases
the distribution limits of a species can be attributed to a lethal
temperature which precludes the species‘ existence,However,a more
widespread type of relationship is one which has a correspondence
between the distribution limits of a species and an isotherm,An
isotherm is a line on a map that joins locations having the same mean
temperatures,Overall,an organism‘s limit to distribution is
determined not by lethal temperatures,but by conditions that make it
a poor competitor,
Key Notes
Species distribution
and temperature
E3 TEMPERATURE AND SPECIES
DISTERIBUTION
对温度的进化反应温度对个体的影响被进化的变异减弱。阿伦法则
（ Allen‘s rule）陈述了来自冷气候中的内温动物与来自温暖气候的内温动物相比，趋向于具有更短的末端
（耳朵和四肢）；因此降低了它们的表面积对体积的比率。这个规律有很广的适用性。贝格曼规律
（ Bergmann‘s rule）讲述了寒冷地区的哺乳动物比温暖地区的哺乳动物个体趋向于更大，也减低了它们的表面积与体积的比率。这个规律没有广泛的种间的适用性，是由于在测定体重中牵涉到其它的重要因子，但是在种内经常是真实的。
相关主题 温度与代谢（ E1） 竞争的性质（ I1）
对温度的响应（ E2） 生态系统格局（ S1）
The effects of temperature on individuals may be moderated by
evolved differences,Allen‘s rule states that endothermic animals
from cold climates tend to have shorter extremities (ears and legs)
compared with animals from warmer climates,thus reducing their
surface area,volume ratio,This rule has widespread applicability,
Bergmann‘s rule states that mammals tend to be larger in colder
areas than warm climates,again to reduce their surface area,
volume ratio,This rule does not have widespread interspecific
applicability due to other important factors involved in
determining body weight,but is often true intraspecifically.
Evolved response to
temperature
Related topics Temperature and metabolism (E1) The nature of competition (I1)Responses to temperature (E2) Ecosystem patterns (S1)
F1 太阳辐射与植物要 点辐射能和光合作用绿色植物能够利用的惟一能源是辐射能。当叶子截获辐射能时，它能被吸收、反射或者透射。吸收的部分能量到达叶绿体，引发了光合作用，在这个过程中，
辐射能被用于转化水和二氧化碳成为糖。太阳辐射包含了不同波长的光谱。然而，仅有一个有限的光谱带对光合作用是有效的。这就是光合活性辐射（ PAR）带，
对绿化植物是位于 380nm到 700nm之间。
F1 SOLAR RADIATION AND
PLANTS
Radiant energy is the sole energy source that can be
used by green plants,When a leaf intercepts radiant
energy it may be absorbed,reflected or transmitted,
Part of the fraction absorbed reaches the chloroplast,
fuelling photosynthesis,the process where radiant
energy is used to convert water and CO2 into sugars,
Solar radiation contains a spectrum of different
wavelengths,However,only a restricted band of this
spectrum is effective for photosynthesis,This is the
band of photosynthetically active radiation (PAR)
and for green plants lies between 380 and 710 nm..
Key Notes
Radiant energy and
photosynthesis
辐射能转换效率计算光合作用效率是有可能的。作为生物化学过程，
光合作用是高效率的；进入反应部位的可用辐射能的
35%转化为潜在能量。在植物水平上的真实效率在
0.5%和 3%之间变化，取决于植物和环境。
C3和 C4植物 植物光合能力中的主要差别是在 C3和 C4植物之间。 C4
植物能捕获 CO2,伴随着水的利用效率比 C3植物更大，
而这优点需要消耗能量。在 C4植物中，光合作用率随光强度而增加，而 C3植物随光强度增加光合作用渐渐减小。
It is possible to calculate the efficiency of
photosynthesis,As a biochemical process
photosynthesis is efficient; 35% of usable4 radiant
energy entering a reaction site is converted to
potential energy,The actual efficiency at the plant
level varies between 0.5% and 3.0%,depending on
the plant and the environment.
Efficiency of radiant
energy conversion
A major difference in the photosynthetic capacity of
plants is that between C3and C4 plants,C4 plants are
able to capture CO2 with greater water use efficiency
than C3 plants,but this advantage comes at an energy
cost,In C4 plants the rate of photosynthesis increases
with light intensity,whilst photosynthesis tails off
with increasing light intensity in C3 plants,
C3 and C4 plants
辐射强度的变化植物很难获得它们完全的光合作用潜能，是由于水短缺和辐射强度的改变。光强度的系统变化是太阳辐射的日节律和年节律。光强度中极少部分的系统变化是因叶子彼此的相对位置引起。
植物对辐射的战略和战术响应植物种间对辐射强度反应的主要战略差异显示为“阳地种”和“阴地种”，它们分别具有适应于高的和低的光辐射范围。同样，植物能够在不同光条件下生长不同的叶子，作为对光环境的部分战术反应。这一点最清楚地在单株植物叶冠内的阳叶和阴叶的结构上看到。
Plants rarely achieve their full photosynthetic potential,
due to water shortage and to variation in the intensity
of radiation,The systematic variations in light
intensity are the diurnal and annual rhythms of solar
radiation,Less systematic variations in light intensity
are caused by the positioning of leaves in relation to
each other.
Changes in the
intensity of radiation
A major strategic difference between plant species in
their response to the intensity of radiation is exhibited
by?sun species‘ and?shade species‘,which possess a
range of adaptations to high and low light levels,
respectively,Also,plants may grow leaves which
develop differently under different light conditions as
part of a tactical response to the light environment,
This is most clearly seen in the formation of sun
leaves and shade leaves within a leaf canopy of single
plant.
Strategic and tactical
response of plants to
radiation
光合作用的控制气孔是为光合作用而吸收 CQ2的通路。然而，如果气孔张开，允许 CQ2进入叶内，水通过蒸发将离开叶子。在大多数陆地生态系统中，至少在一段时间内，当水的供应短缺时，光合作用控制的某些形式必定启用。植物对这种困境具有大量的对策回应。
The leaf stomata are the route for the uptake of CO2 for
photosynthesis,However,if stomata are left open to
allow CO2 to enter the leaf,water will leave the leaf via
transpiration,As water is in short supply in most
terrestrial ecosystems for at least some of the time,
some form of photosynthetic control must be operated,
Plants have a number of strategic responses to this
dilemma.
Control of
photosynthesis
光合作用的测量光合作用速率是总速率的测量，即植物捕获的辐射能，
并把它固定到碳的化合物中。光合作用净同化是同化量的呼吸的丢失量之差。因此，净同化在黑暗中是负值，并随 PRA增加而增长。在光合作用的同化量等于呼吸消耗量时的 PRA强度，称为 补偿点 （ compensation
point）
相关主题 太阳辐射与气候（ C1） 对温度的响应（ E2）
植物与水（ D2） 温度与物种分布（ E3）
温度与代谢（ E1） 生态系统格局（ S1）
Related topics Temperature and metabolism (E1) The nature of competition (I1)
Responses to temperature (E2) Ecosystem patterns (S1)
The rate of photosynthesis is a gross measurement of
the rate at which a plant captures radiant energy and
fixes it into carbon compounds,Net assimilation is the
difference between photosynthetic assimilation and
losses due to respiration,Therefore,not assimilation
will be negative in the dark and will increase with
increasing PAR,The intensity of PAR at which the gain
in photosynthesis equals the losses is known as the
compensation point.
Measurement of
photosynthesis
G1 资源与循环要 点营养物资源 群落以形形色色的方式获得和损失营养物。机械风化、
化学腐蚀，特别是碳酸化作用，都是重要的过程。矿物质在水中的简单溶解也使营养物从岩石和土壤中获得成为可能。在水流中水可能携带着营养物，给下流地区提供一个重要的资源。大气也提供营养物，特别是二氧化碳和氮。大气中其他营养物可能以湿降落
（雨，雪和雾）和干降落（干燥期间的颗粒沉淀物）
的方式回到群落。
G1 SOURCES AND CYCLES
Nutrients are gained and lost by communities in a
variety of ways,Mechanical weathering,chemical
weathering,particularly carbonation,are important
processes,Simple dissolution of minerals in water
also makes nutrients available from rock and soil,
Water may carry nutrients in watercourses providing
an important source in downstream areas,
Atmospheric gases provide nutrient sources too,
particularly carbon dioxide and nitrogen,Other
nutrients from the atmosphere become available to
communities as wetfall (rain,snow and fog) and
dryfall (settling of particles during dry periods).
Key Notes
Nutrient sources
陆地群落营养物预算有机体吸收的特定营养物微粒可连续地循环，直到营养物最终损失，这是通过许多过程中的任一个过程把营养物从系统中除去。营养物释放可直接到达空气或通过细菌作用（如甲烷）。对于许多元素来说，最重要的是丢失途径是在水流中。营养物损失的其他途径包括火灾、庄稼的收获和森林砍伐。
A particular nutrient atom taken up by an organism
may cycle continuously until eventually the nutrient
will be lost through any one of a number of processes
that remove nutrients from the system,Release may
be direct to the atmosphere or via bacterial action (as
in the case of methane),For many elements,the most
substantial pathway of loss is in streamflow,Other
pathways of nutrient loss include fire,the harvesting
of crops and deforestation.
Nutrient budgets in
terrestrial
communities
水生群落营养物预算水生系统从水流中得到它们所需的大量营养物。在具有流出口的溪流、河流和湖泊中，水流出是个重要因素。通常，无机营养物置换阶段与营养物固定在生物量中的时期是交替进行的。浮游生物在湖泊中的营养物循环中起关键作用。海洋含有温暖的表层水，生活着大多数的植物，还有冷的深层水（占总水容量的
90%）。表层水的营养物来源于两种方面：（ i）深层水的上涌流（组成物预算的 95%以上），（ ii）河流的输入。
Aquatic systems obtain the bulk of their supply of
nutrients from streamflow,In streams,rivers and lakes
with a stream outflow,export in outgoing stream
water is a major factor,Commonly,phases of fast
inorganic nutrient displacement alternate with periods
when the nutrient is locked in biomass,In lakes,
plankton play a key role in nutrient cycling,Oceans
contain warm suface waters,where most plant life is
found and cold deep waters (which make up 90% of
the total water volume),Nutrients in the suraface
waters come from two sources,(i) upwelling from
deep water (which comprise over 95% of the nutrient
budget),and (ii) river input.
Nutrient budgets in
aquatic communities
地球化学 地球上的化学元素库存在于各种圈层（ compartments）
中：在岩石（岩圈）和土壤水、溪流、湖泊或海洋
（可组合构成水圈）中。在上述情况下，化学元素以无机形式存在。同时，生命有机体和已死亡及腐烂的有机物质是在含有有机元素的圈层里。研究在这些区域内发生的化学过程和圈层间元素的流动（通过生物过程产生了功能性的改变和影响），称为生物地球化学。
The pools of chemical elements on earth exist in
various compartments,in rocks (the lithosphere),
and soil water,streams,lakes or oceans (whish,
combined,constitute the hydrosphere),In all these
cases,the chemical elements exist in the inorganic
form,In contrast,living organisms and dead and
decaying organic matter are compartments which
contain elements in the organic form,Studies of
the chemical processes occurring within these
compartments and the flux of elements between
them (which are fundamentally altered and
affected by biotic processes) is termed
biogeochemistry.
Geochemistry
全球生物地化循环陆地植物利用空气中 CO2作为光合作用的碳源，而水生植物使用溶解的碳酸化合物（水圈的碳）。呼吸作用把固定在光合产物中的碳，再释放到气圈和水圈的碳圈层中。在全球氮循环中，气相是占优势的，其中，
氮的固定和微生物的脱氮作用特别重要。磷主要储存在土壤水、河流、湖泊、岩石和海洋沉淀物中，而硫储存在大气和岩石的组分中。
相关主题 植物与消费者（ G2） 土壤形成、特性和分类（ G3节）
初级和次级生产力（ P2）
Terrestrial plants utilize atmospheric CO2 as their
carbon source for photosynthesis,whereas aquatic
plants use dissolved carbonates (hydrosphere carbon),
Respiration releases the carbon locked in
photosynthetic products back to the atmospheric and
hydrospheric carbon compartments,The atmospheric
phase is predominant in the global nitrogen cycle,in
which nitrogen fixation and denitrification by
miocroorganisms are of particular importance,The
main stocks of phosphorus occur in soil water,
atmospheric and lithospheric components.
Geochemistry
Related topics Plants and consumers (G2) Primary and secondary production
Soil formation,properties and (P2)
classification(G3)
G2 植物与消费者要 点群落中物质的命运生命物质的主要基本组成分是碳。当通过光合作用固定 CO2,利用太阳能把 CO2 和水合成糖时，使碳进入群落的营养结构中。这样碳成了净初级生产力（ NPP）
这就是在光合作用中每单位时间植物积累的总能量。
当储存碳的高能量分子最终用于提供工作能量时，碳就以 CO2 的形式释放到大气中。
G2 PLANTS AND CONSUMERS
The main elemental component of living matter is
carbon,Carbon enters the trophic structure of a
community when CO2 is fixed through photosynthesis,
the utilization of the energy of sunlight to combine CO2
and water into sugars,It then becomes incorporated in
net primary production (NPP),This is the total energy
accumulated per unit time by plants during
photosynthesis,When the high-energy molecule in
which the carbon was stored is finally used to provide
energy for work,the carbon is released into the
atmosphere as CO2.
Key Notes
The fate of matter in
the community
生 产 者 自养生物 ——大多数陆地生态系统的主要生产者，利用太阳能或无机物质氧化作用的能量，使无机分子成为有机分子。在陆地系统中植物是主要的生产者，而浮游植物在开放海洋中最重要。在深水域中，光合产物只在上层部分（透光区）产生，因为光能透入这部分。在更深水域中，光不能透入，故这无光区没有光合作用发生。
消 费 者 植物被初级消费者所食，如草食哺乳动物和昆虫。海洋里，浮游动物以浮游植物为食。这些初级消费者依次又被次级消费者 ——肉食动物所食，如哺乳动物和蜘蛛。在海洋中，很多鱼类以浮游动物为食时成为次级消费者。
Autotrophs,the main producers in most terrestrial
ecosystems,use energy from the sun or from the
oxidation of inorganic substrates to produce organic
molecules from inorganic ones,Plants are the main
producers in terrestrial systems,while phytoplankton are
the most important in open oceans,In these deep waters,
photosynthetic production occurs in the upper levels,the
photic zone,where light can penetrate,In deeper waters,
light does not penetrate and no photosynthesis occurs in
this aphotic zone.
Producers
Plants are eaten by primary consumers,such as grazing
mammals and insects,In oceans,phytoplankton are
consumed by zooplankton,These primary producers are
in turn eaten by secondary consumers,carnivores such
as mammals and spiders,In oceans,many fish are
secondary consumers as they feed on zooplankton.
Consumers
分 解 者 在生态系统中组成生命有机体的有机物质，最终经分解以可被植物利用的形式回到生物环境中被重新利用。
分解者以无生命的有机物质为食，是这个再循环中的有机体。最重要的分解者是细菌和真菌。
相关主题 资源与循环（ G1） 食物链（ P3）
初级和次级生产力（ P2）
Related topics Sources and cycles (G1) Food chains (P3)
Primary and secondary production (P2)
The organic material that composes living organisms in
an ecosystem is eventually recycled,broken down and
returned to the abiotic environment in forms that can be
used by plants,Decomposers,which feed on nonliving
organic material are the organisms in this recycling,
The most important decomposers are bacteria and fungi.
Decomposers
G3 土壤形成、特性和分类要 点土壤形成 在陆地生态系统的底部是土壤：一薄层由生物和气候改造的地球外壳。土壤提供了栖息地，具有营养物传递系统、再循环系统和废物处理系统。土壤的研究称为土壤学。土壤中的有机体参与了栖息地的形成，是土壤形成中构成五个相互作用的因素之一；其他四个是气候、地形、母质和时间。土壤母质的开始居住者通常是蓝细菌，它能进行光合作用和固定氮。高等植物形成后，土壤变化过程的多样性产生了活的和死的细胞，和土壤有机物质（ SOM）的动态混合物。
G3 SOIL FORMATION,PROPERTIES
AND CLASSIFICATION
Underlying terrestrial ecosystems is the soil; a thin layer of
the Earth‘s crust that has been remade by life and weather,
Soil provides habitats with a nutrient delivery system,a
recycling system and a waste-disposal system,The study of
soils is called pedology,Soil organisms participate in the
formation of the habitat and constitute one of the five
interactive factors in soil formation; the other four are
climate,topography,parent material and time,The initial
colonizers of soil parent material are usually the
cyanobcteria,capable of photosynthesis and nitrogen
fixation,After higher vegetation has become established,a
variety of soil processes produces the dynamic mixture of
living and dead cells,soil organic matter (SOM).
Key Notes
Soil formation
土壤剖面 土壤表面是死亡腐烂植物部分的枯枝落叶层，下面由完全不同的物质组成的一层或多层。这些层可叫做
“层”土层的形成是由于腐烂植物与矿物质土壤的上层相混合。下面的亚土壤是土壤起始形成的地方，称为母质。这种分层的外貌叫做土壤剖面。土壤科学家认为母质以上的土层有三类,A,B和 C层。这三层之下是不变的母质。这些以 R层著称。土壤剖面是重要生态系统过程中一个即时指标。
At the surface of soil is a litter of dead or rotting plant
parts,with one or more distinctly different layers
underneath,These layers have come to be called
horizons‘,Soil horizons form as rotting plant parts
mix with the upper layers of the mineral soil,The
subsoil underneath is the earth from which the soil
was made and is called the parent material,This
layered appearance is called the soil profile,Soil
scientists recognize three kinds of soil horizon above
the parent material; the A,B and C horizons,Under
these three groups of horizons is the unaltered parent
material,These are known as R horizons,The soil
profile is an instant indicator of important ecosystem
processes,
The soil profile
主要分类：
大土壤群在全球范围上，大土壤群在土壤分类中是最容易制图划分的。土壤剖面的颜色和条带用来区分大土壤群。
全球土壤图表示了一个粗略的大土壤群图，与气候和植被图很相似。土壤勘测员是以农田或郡县部分为尺度来绘制土壤图。通常只有大土壤群之一会存在。所使用的单位“土系”，是指从相同类型的母质，通过相同类型的结合过程而发展起来的一类土壤，它们的土层在它们的排列和一般特性上是完全相似的。
相关主题 演替（ R1） 生态系统格局（ S1）
Related topics Succession (R1) Ecosystem patterns (S1)
On a world scale,the great soil groups are the most easily
mapped of any class in a soil classification,Color and banding
of the soil profile distinguish the great soil groups,World soil
maps represent a rough plot of the great soil groups and are
very similar to maps of climate or vegetation,Soil surveyors
map soils on the scale of farm fields or parts of counties,
Usually only one of the great soil groups will be present,The
units used,?soil series‘,are a group of soils developed from
the same kind of parent material,by the same generic
combination of processes,and whose horizons are quite
similar in their arrangement and general characteristics.
Primary
classification,the
great soil groups
H1 种群和种群结构要 点种 群 种群是一定区域内同种生物个体的集合。种群间的边界可以是任意的。种群可以根据组成种群的生物是单体生物还是构件生物进行分类。在单体生物种群中，
每一受精卵发育成一单个个体。在构件生物种群中，
受精卵发育成一个结构单位，这一结构单位再形成更多的构件和分支结构。然后这些结构可能分裂，形成许多无性系分株。
H1 POPULATIONS AND
POPULATION STRUCTURE
A population is a group of organisms of the same species
which occupies a given area,The boundaries between
populations can be arbitrary,Populations may be
categorized as consisting of either unitary or modular
organisms,In unitary populations,each zygote gives rise
to a single individual,In modular organisms,the zygote
develops into a unit of construction which gives rise to
further modules and a branching structure,The structure
may then may then fragment producing many individual
ramets.
Key Notes
Population
种群大小 对于单体生物和种群如哺乳类，其种群大小就是一定区域内个体的数量，非常简单。对于构件生物，如植物和珊瑚，情况就较复杂。对于这些种群，“断片”
（无性系分株）或枝条（构件）的数目比不同个体的数量更有意义代表多度。
The population size for unitary organisms,such as
mammals,is simply the number of individuals in a
given area,For modular organisms,such as plants
and corals,The situation is more complex,In this
case the number of?pieces‘ (ramets) or the number of
shoots (modules) may give a more meaningful
indication of abundance than the number of different
individuals.
Population size
年龄和时期结构种群的年龄结构是每一年龄阶段个体数目的比率，通常以年龄金字塔图来表示。既不增长也不下降的种群有稳定的年龄分布。增长型的种群有更多的年轻个体，
而在下降型种群中年老的个体占优势。当种群经历离散和发育时期（如昆虫的龄期）时，每一时期个体的数目（“时期结构”）可以对种群进行有效的描述。
对于生长率无法预测的物种（如植物），根据大小分类可能更有意义。
相关主题 出生率、死亡率和种群增长（ H2） 竞争的性质（ I1）
密度和密度制约（ H3） 捕食的性质（ J1）
种群动态 ——波动、周期和混沌（ H4）
The age structure of a population is the number of individuals
in each age class expressed as a ratio,and is usually displayed
nor contracting nor contracting will have a stationary age
distribution,A growing population will have more young,
While a declining population will be dominated by older age
classes,Where organisms pass through discrete growth stages
(e.g,insect larval instars),the number of individuals at each
stage (the?stage structure‘) may provide a useful description
of the population,In species where growth rates are
indeterminant (such ax plants),size classes may be more
informative.
Related topics Natality,mortality and population The nature of
competition (I1) growth (H2)
The nature of predation (J1) Density and density
dependence (H3)
Population dynamics – fluctuations,cycles and chaos (H4)
Age and stage
structure
H2 出生率、死亡率和种群增长要 点出 生 率 出生率就是新个体的产生，实际出生率就是一段时间内每个雌体实际的成功繁殖量。特定年龄出生率就是特定年龄组内雌体在单位时间内产生的后代数量。
死 亡 率 死亡率是在一定时间段内死亡个体的数量除以该时间段内种群的平均大小。这是一个瞬时率，可用来估价整个种群的死亡率或特定年龄群的特定年龄死亡率，
死亡的概率是死亡个体数除以在每一时间段开始时的个体数。
H2 NATALITY,MORTALITY AND
POPULATION GROWTH
Nntality is the birth of new individuals,The realized
natality is the actual successful reproduction per female
over a period of time,The age-specific birthrate is the
number of offspring produced per unit time by females in
specific age classes,
Key Notes
Natality
The death rate,or mortality rate,is the number of
individuals dying during a given time interval divided by
the average population size over that time interval,This is
an instantaneous rate and be estimated for the population as
a whole or for specific age classes to give the age specific
mortality rate,The probability of dying is the number
dying per individual present at the start of the time period.
mortality
存 活 率 存活率是死亡率的倒数。对于一个特定种群，存活率的数据通常以存活曲线的形式来表示；存活曲线表示的是在每一个生活期存活个体所占的比率的对数值。根据各种生活期死亡率的高低，特定年龄存活曲线一般有三种模式：后期死亡率最高（类型 I），各期死亡率相等（类型 II），早期死亡率最高（类型 III）。
生 命 表 生命表总结了一组出生时间大体相同的个体从出生到死亡的命运，这样的一组个体称为同生群，这样的调查称为同生群分析。生命表表示存在于不同生命阶段或年龄个体的数量，以及每一阶段的年龄特定存活率和年龄特定死亡率。
每一阶段的死亡率用 k值表示,k是通过对数函推导出来的，
并且可以相加得出总死亡率。
Survivorship is the converse of mortality,Survivorship data
are often shown as a survivorship curve for a particular
population; a graph showing the proportion of survivors on
a logarithmic scale through each phase of life,There are
three generalized patterns of age-specific survivorship
depending on whether the probability of dying is highest
later in life (Type I),constant through life (Type II) or
highest for young stages (Type III).
Survivorship
Life tables summarize the fate of a group of individuals
born at approximately the same time from birth to the end
of the life cycle,Such a group is known as a cohort and
investigation of this kind is termed cohort analysis,Life
tables show the number of individuals present at different
life stages or ages together with age-specific survival rates
and age-specific mortality rates calculated for each stage,
Mortality at each stage is expressed by k-values which are
derived from logarithms and can be summed to give total
mortality
Life tables
K-因子分析 这一方法可以辩明关键因子对死亡率的作用。连续几年获得的特定阶段 k值与总死亡率（ k总 ）相比。 K
因子分析强调那些死亡率最高的阶段，这些阶段是种群丧失率和种群大小波动的关键。
生殖力表 生殖力是指同一个体生产的卵、种子或处于生活史第一阶段后代的数目。生殖力表可计算基础生殖率 R0。
R0是在同生群结束时每个亲体产生后代的数量。在一年生种群中,R0表示在这段时间内，种植增长或下降的总的程度。
This technique allows the identification of key factors
contributing to mortality,Stage-specific k-values
obtained over successive years are compared to the
values for total mortality (ktotal),K-Factor analysis
highlights those stages suffering the greatest mortality
which are responsible for fluctuations in loss rate and
hence population size,
k-Factor analysis
Fecundity is the number of eggs,seeds,or offspring in
the first stage of the life cycle produced by an
individual,The fecundity schedule allows the
calculation of the basic reproductive rate R0,This is the
number of offspring produced per original individual by
the end of the cohort,In an annual population,it
indicates the overall extent to which the population has
increased or decreased over that time.
The fecundity
schedule
种群增长 种群大小随时间的变化可以按如下方法计算,t时间种群原来数量（ Nt），加上新出生的个体数（ B）和迁入个体数（ I），减去死亡个体数（ D）和迁出的个体数
（ E），就可得到 t+1时间种群的数量（ N t+1），这可用以下方程表示。
N t+1= Nt +B + I – D – E
在一组特定条件下，一个体具有最大的生殖潜力，称为内禀自然增长率 r。这是种群在不受资源限制的情况下，于一定环境中可达到的理论最大值。
The changes in population size over time can be
calculated by adding birth (B) and the number of
immigrants (I)to the original population at time t,(Nt ),
and subtracting the number of deaths (D) and emigrants
(E) to give a new population size an the time t+1(Nt+1),
This is represented by the equation;
N = N +B + I – D – E
For a particular set of conditions,an individual has a
maximum potential for reproduction which is its intrinsic
natural rate of increase,r,This is the theoretical
maximum that may be reached in a given environment if
the population is not resource-limited.
population
growth
非密度制约性种群增长这种无限增长可用连续型种群模型来描述，以在 t时间时，种群数量的变化率来表示：
t时间种群大小的变化率 =内禀增长率 × 种群大小
dN/dt = rN
Unlimited growth of this kind is described by a
continuous population model and expressed in terms
of the rate of change in population numbers at time t:
Rate of change of population Intrinsic rate
of increase
Size at time t =× population size
dN/dt = rN
Density-
independent
population growth
密度制约性种群增长：
逻辑斯谛方程逻辑新谛方程描述的是一个在有限资源空间中的简单种群的增长。在早期，资源丰富，死亡率最小，繁殖尽可能的快，
种群内个体可达到内禀增长率。种群呈几何式增长，直到种群数量达到环境可持续支持的最大程度，这个最大数量称为环境容纳量（ K）。当种群更加拥挤时，种群增长率减少到零，
种群大小处于稳定状态。这可用逻辑斯谛方程来表示：
T时间种群大小变化率 =内禀增长率 × 种群大小 × 密度制约因子
dN/dt = rN(1 - (N/K))
当种群达到环境容纳量，种间竞争变得更激烈时，密度制约因子（ 1 - (N/K)）会接近零。该方程预测种群的增长随时间变化呈现出,S‖形，如在真实种群中通常所观察的那样。
相关主题 种群和种群结构（ H1） 竞争的性质（ I1）
密度和密度制约（ H3） 捕食的性质（ J1）
种群动态 ——波动、周期和混沌（ H4）
The logistic equation describes the growth of a simple population in a confined
space,where resources are not unlimited,In the early stages resources are
abundant,the death rate is minimal and reproduction can take place as fast as
possible allowing the individuals to attain their intrinsic rate of increase,The
population increases geometrically until the maximum number of individuals
the environment can sustainably support is approached,This maximum number
is called the carrying capacity (K),The population growth rate declines to zero
as the population becomes more crowded and the population size stabilizes,
This can be described as the logistic equation,
Rate of change of Intrinsic rate Population Density dependent
Population size at time t = of increase × size × factor
Dn/dt=rN(1-N/K)
Where the density-dependent factor,(1-N/K)approaches zero as the population
approaches the carrying capacity and intraspecific competition becomes more
intense,This equation predicts growth of a population over time to be
sigmoidal,as is commonly observed in real populations,
Related topics Populations and population structure (H1) The nature of competition (I1)
Density and density dependence (H3) Population dynamics-fluctuations,
cycles and chaos (H4)
Density-dependent
growth-the logistic
equtation
H3 密度和密度制约要 点密 度 密度为单位面积、单位体积或单位生境中，个体的数量，对于一些植物和大型的或显眼的动物，可以计数它们的总的数量，对于许多在一定地区只能获得一部分样品的动物，其密度就必须进行估计。
H3 DENSITY AND DENSITY
DEPENDENCE
Density is defined as the number of individuals per unit
area,per volume or per unit of habitat.Total counts may be
obtained for some plants and large or conspicuous animals,
For many animals only a proportion of the individuals
present in a given area will be detected and density must be
estimated.
Key Notes
Density
密度制约 如果种群参数如出生率和死亡率随着种群密度的变化而变化，就可以说是密度制约的。如果出生率和死亡率不随着密度的变化而变化，则是非密度制约性的。
如果没有迁移，除非出生率和死亡率是密度制约性的，
否则种群会持续增长。
估计密度：
标志重捕法估计绝对密度可以使用以下方法：捕捉、标记捕捉个体、释放和再次捕捉。如果是随机捕捉，在第二次捕捉到的个体中，标记与没有标记个体的比例同整个种群中标记与没有标记个体的比例应当相等。因为已标记的总的个体数目是已知的，因此可根据以下公式来预测种群的总数量：
捕捉到的个体数 /重捕个体数 × 原来标记个体数
= 种群总的个体数
Estimates of absolute density can be made with this method which involves
trapping,marking trapped individuals,releasing them and trapping a second
time,The proportion of marked to unmarked individuals in the traps will be
the same as the proportion of marked to unmarked in the whole population,
assuming a random proportion of the population is trapped,Since the total
number of marked animals is known an estimate of the total population can
be obtained from the following equation:
Number trapped
Number recaptured
× Number originally marked = Total number in
population
Estimation
density-mark
release recapture
Population parameters such as birth and death rates which vary with density
are said to be density dependent,Birth and death rates that do not change
with density are density independent,In the absence of immigration,a
population will continue to increase in number unless either the per capita
birth rate or death rate is density dependent,
Density
dependence
补偿和密度制约密度制约有三种形式：过度补偿，补偿不足和准确补偿。如果密度制约引起的数量下降，没有超过或等于开始增加的个体数量，则密度制约是补偿不足。当密度制约的效应超过了开始种群数量的增加，称为过度补偿。如果下降个体数与开始增加的个体数相等，则称密度制约为准确补偿。
相关主题 种群和种群结构（ H1） 种群动态 ——波动、周期和混沌（ H4）
捕食的性质（ J1） 竞争的性质（ I1）
出生率、死亡率和种群增长（ H2）
平衡种群密度 当单位个体出生率正好平衡单位个体死亡率，种群密度既不增加也不减少时，此时的种群密度为平衡种群密度。平衡种群密度与环境容纳量 K值相等。
The equilibrium population density occurs when the per capita death
rate exactly balances the per capita birth rate such that the density is
neither increasing nor decreasing,The equilibrium population density
is equivalent to the carrying capacity K.
Related topics Populations and population structure Population dynamics-
fluctuations,
(H1) cycles and chaos (H4)
Natality,mortality and population The mature of competition (I1)
growth (H2) The mature of predation (J1)
Equilibrium
population density
Compensation and
density dependence
There are three types of density dependence,overcompensating,under
compensating and exactly compensating,If a decline in numbers due
to density dependence does not outweigh or balance the initial
increase in numbers,density dependence is under
compensating.Overcompensating density dependence occurs where
the effect of increased density more than outweighs the initial
augmentation.If the decline in numbers exactly balances the initial
increase in density,density dependence is said to be exactly
compensating,
H4 种群动态 ——波动、周期和混沌要 点增长种群和收缩种群大多数实际种群并不是在平衡密度停留很长时间，而是动态的不断的发生变化。由于周围环境的变化或生物因子的影响，种群可能会增长或收缩。
H4 POPULATION DYNAMICS –
FLUCTUATIONS,CYCLES
AND CHAOS
Most real populations are not at their constant equilibrium
density for very long,but are dynamic and changing,
Populations may be expanding or contracting because of
changes in environmental conditions or because of changes
to their biotic environment.
Key Notes
Expanding and
coutracting
populations
种群波动 种群波动可能有以下几个原因：
（ i）时滞或称为延缓的密度制约，存在于密度变化及其对种群大小的影响之间。种群可能超过环境容纳量，
然后逐渐减少，在最终达到平衡之前呈现减幅振荡。
这种延缓的密度制约可能使捕食者和猎物多度之间产生周期。
（ ii）过度补偿性密度制约。其可能导致减幅振荡、稳定极限环（非减幅振荡的有规律周期变化）或无规则随机振荡。
（ iii）环境随机变化。环境条件非确定性的、不可预见性的变化会导致平衡密度的变化。
Populations
fluctuations
Populations may fluctuate for a number of reasons:
(i) A time lag between a change in density and its effect on
the population size,or delayed density dependence,The
population can overshoot the carrying capacity and then
show gradually diminishing,dampened oscillations before
eventually stabilizing at equilibrium.This delayed density
dependence may also produce cycles in predator and prey
abundance;
(ii) Overcompensating density dependence,This can lead to
dampened oscillations,stable limit cycles (regular cycles
that do not damp down) or chaotic fluctuations that appear
random;
(iii) Environmental stochasticity,This is a nondeterministic,
unpredictable variation in the environmental conditions,
resulting in a changing equilibrium density.
相关主题 出生率、死亡率和种群增长（ H2） 捕食行为猎物反应（ J2）
密度和密度制约（ H3）
混 沌 数学上有关混沌的定义与俗语中的用法是截然不同的。
一个混沌系统是受确定性作用控制的，而不是随机的。
混沌的结果依赖于初始状态的精确值。由于完全精确是不可能达到的，因此对混沌系统不能进行有效的预测。目前，对于观察到的有关种群大小波动在何种程度上是受混沌过程影响的还不清楚。一些分析认为，
麻疹的爆发和一些昆虫种群可能表现出混沌的动态变化。
Related topics Natality,mortality and population Predator behavior
and prey growth (H2)
response (J2)
Density and density dependence (H3)
Chaos The mathematical definition of chaos is quite distinct from the
colloquial use of this term,A chaotic system is driven by a
deterministic process,it is not conditions,As perfect accuracy is
impossible to attain,chaotic systems are effectively
unpredictable,It is currently unclear to what extent observed
fluctuations in population sizes are influenced by chaotic
processes,Some analyses suggest that measles outbreaks and
some insect populations may display chaotic dynamics.
I1 竞争的性质要 点相互作用的分类个体或物种间的相互作用可以相互作用的机制和影响为基础来分类。关键的种间相互作用是竞争、捕食、寄生和互利共生，而主要的种内相互作用是竞争、自相残杀和利他主义。
I1 THE NATURE OF COMPETITION
Interactions between individuals and species can be
classified on the basis of the effects and the mechanism of
the interaction,The key interspecific interactions are
competition,predation,parasitism and mutualism,whilst
the main intraspecific interactions are competition,
cannibalism and altruism.
Key Notes
Classifying
interactions
竞 争 竞争是共同利用有限资源的个体间的相互作用，会降低竞争个体间的适合度。竞争即可在利用共同资源的物种间发生（种间竞争），也可在同种个体间发生
（种内竞争）。个体或物种的生态位（它所处的环境，
利用的资源和它发生的时间）是决定该个体或物种与其他个体或物种竞争程度的关键。大范围的生态位重叠一般导致激烈竞争。
Competition is an interaction among individuals utilizing a
limited resource,resulting in reduced fitness in the competing
individuals,Competition occurs both between species utilizing
a shared resource (interspecific competition) and among
members of a species (intraspecific competition),The niche of
an individual or species (the conditions under which it is
found,the resources it utilizes and the time it occurs there) is
critical in determining the degree of competition with other
species or individuals,Large niche overlap generally results in
intense competition.
Competition
种内竞争 当个体对资源的需要非常相似时，竞争会特别强烈。种内竞争是生态学的一种主要影响力，
是扩散和领域现象的原因，并且是种群通过密度制约过程进行调节的主要原因。
种间竞争 种间竞争发生在利用同样有限资源的两物种之间。极少种能够逃脱其他种与之竞争共同资源的影响。
Interspecific competition occurs between two species
using the same limited resource,Very few species can
escape from the effects of other species competing for the
same resource.
Interspecific
Competition
As individuals are quite similar in their resource
requirements,such competition may be particularly
intense,Intraspecific competition is a major force in
ecology and is responsible for phenomena such as
dispersal and territoriality,as well as being the primary
cause of population regulation via density-dependent
processes.
Interspecific
Competition
利用性竞争 竞争有两种作用方式。在资源利用性竞争方式下，个体不直接相互作用，而是耗尽资源使供应不足。由于可利用资源不足而造成适合度下降。
干扰性竞争 在干扰性竞争方式下，个体直接相互作用，在一些动物种类中，最明显的通过打斗，也通过产生毒物（如植物异株克生）进行竞争。在这种相互作用中“败者”
适合度下降，可能由于干扰（如受伤或死亡），也或许由于缺乏可用资源。
In interference competition,individuals interact directly,
most obviously,in the case of some animal species,by
fighting,but also by producing toxins (e.g,plant
allelopathy),Fitness reduction in the?loser‘ in such
interactions may be due to the interference (e.e,injuries or
death) as well as the lack of resource access.
Interfernce
Competition
There are two ways in which competition can operate,In
exploitation competition,individuals only interact
indirectly,by depleting the resource in short supply,
Reduced fitness occurs due to a shortfall in resource
availability.
Exploitation
Competition
相关主题 生态位（ B3） 资源分配（ I3）
种内竞争（ I2）
竞争结果的不对称竞争通常不均等的影响竞争者，一个体的竞争代价远高于另一个体。竞争杀死失败者是很普遍的，或通过掠夺资源或通过干扰。
Competition often unevenly affects competitors,such that
the cost for one individual is far greater than for another,It
is common for competition to kill the losers,either via
exploitation or interference.
Asymmetry in
the effects of
Competition
Related topics The niche (B3) Resource partitioning (I3)
Intraspecific competition (I2)
I2 种内竞争要 点密度制约 密度制约描述适合度与种群大小之间的关系。种群调节的一个关键因子是负的密度制约，当种群密度增加时，由于种内竞争，使适合度下降。
I2 INTRASPECIFIC COMPETITION
Density dependence describes the relationship between fitness
and population size,A key population regulatory factor is
negative density dependence,where declining fitness occurs
as population density increases within a species due to
intraspecific competition.
Key Notes
Density
dependence
扩 散 生物可通过扩散离开种群密度高的地区，来对高水平的种内竞争做出反应。即使在生活周期内大部分时间营固着生活的种类，也有一个可运动的扩散期。扩散通常由种群内较年轻的个体进行，而在许多哺乳动物中雄性比雌性扩散更多。
领 域 性 许多动物种（包括昆虫、鸟类和哺乳动物）的个体或群体为争夺空间而竞争。保持领域边界的个体间有积极的相互干扰行为。领域使其所有者受益，为对抗入侵者，保护领域所付出的代价，被增加的食物供应、
提高的交配成功率和降低的被捕食的危险所带来的价值超过。
Organisms can respond to high levels of intraspecific
competition by dispersing away from the area of high
population.density,Even in species that are sessile for most of
the lifecycle,there is a mobile dispersal stage,Dispersal is
often undertaken by the younger members of a population,
whilst in many mammal species males disperse more than
females to
Dispersal
In many animal species (including insects,birds and
mammals) individuals or groups compete for areas of space,
There is active interference between individuals to maintain
the territory boundaries,Territoriality gives a benefit to the
territory-holder,such that the costs of defending the territory
against intruders are outweighed by advantages such as in
creased food supplies,increased mating success and reduced
predation risk.
Territoriality
自 疏固着生长的生物，包括植物，不能通过运动逃避竞争，
因此竞争中的失败者死去在同样年龄大小的植物群中，
这种竞争结果使较少量的较大个体存活下来。这一过程叫做“自疏”。自疏导致密度与植物个体大小之间的关系，这在双对数作图时呈现典型的 -3/2斜率。这种关系叫做 Yoda-3/2自疏法则。
相关主题 生态位（ B3） 竞争的性质（ I1）
密度和密度制约（ H3） 资源分配（ I3）
Related topics The niche (B3) The mature of competition (I1)
Density and density dependence (H3) Resource partitioning (I3)
Sessile organisms,including plants,cannot escape
competition by movement,and therefore the losers in the
competitive battle die,In a group of plants of the same age,
this results in fewer individuals of larger size surviving,
This process is described as?self-thinning‘,Self-thinning
results in a relationship between density and individual
plant mass,which typically has a slope of –3/2on a log-log
plot,This relationship is known as Yoda‘s –3/2 law.
Self-thinning
I3 资源分配要 点竞争排斥 如果两个物种在稳定环境中竞争，则有两种可能的结果：（ i）一种被排除，或（ ii）两种共存。竞争排斥原理陈述，共存只能发生在两物种生态位分化的稳定环境中。
极限相似性 共存各需要多少生态位分化？在资源利用分化上的临界阈值叫做极限相似性。
If two species compete in a stable environment,there are two
possible outcomes; (i) one species is excluded,or (ii) both
species coexist,The competitive exclusion principle states
that coexistence can only occur in a stable environment if the
species niches are differentiated.
Key Notes
Competitive
exclusion
How much niche differentiation is needed for species to coexist?
This critical threshold of differentiation in resource utilization is
termed the limiting similarity.
Limiting
similarity
I3 RESOURCE PAPTITIONING
性状替换 当明确的生态位契约受到竞争影响时，为了适应新的资源谱，个体形态会相应变化。这种性状替换发现在收获蚁 Veromessor Pergandei 和达尔文雀,Geospiza
fortis和 G,fuliginosa。
竞争释放 在缺乏竞争者时，物种会扩张其实际生态位。这种竞争释放的例子包括新几内亚岛上的地鸽子和以色列的沙鼠。
In the absence of a competitor,a species may expand its
niche,Examples of such competitive release include ground
doves in New Guinea and gerbils in Israel.
Competitive
release
When realized niches contract under the influence of
competition,morphological changes may follow as
adaptations to the new resource spectrum,Such character
displacement is found in the ant Veromessor pergandei and
in Darwin‘s finches,Geospiza fortis and G,fuliginosa.
Character
displacement
空间和空间异质性环境是许多不同质量、不同资源水平的生境的拼缀。
一些斑块的发生是暂时的和不可预测的。在时间和空间上，环境是异质性的。这意味着竞争“战斗”在环境变化和竞争平衡变化之前不会完成。因此，在现实世界中共存的种类，其共存可能是因为环境的异质性，
而不是因为生态位分化。
表观竞争 如果捕食者进攻两种猎物，那么每一种猎物，会通过增加当地捕食者种群的数量，相反地影响另一种。因此，两个猎物种群之间的相互作用看上去似乎它们确实是在竞争，然而它们或许利用完全不同的资源。这一现象叫做表观竞争。
Environments are patchworks of pabitats of varying
qualities and differing resource levels,Some patches are
temporary and /or unpredictable in occurrence,In time
and space,the environment is heterogeneous,This means
that competitive?battles‘ may not be completed before the
environment changes and the balance of play alters,
Therefore,species that coexist in the real world may do so
because of environmental heterogeneity rather than niche
differentiation.
Spatial and temporal
heterogeneity
If a predator attacks two prey species,then each prey
species may adversely affect the other,by increasing the
local predator population,Therefore,the interaction
between the two prey species is exactly as if they were
competing,yet they may utilize entirely different
resources,This phenomena is known as apparent
competition.
Apparent competition
无敌空间如果两种间发生表观竞争，它们可能试图避开捕食者的影响，离开另一种猎物周围到一种叫做“无敌空间”的生境中去。因此，生态位分化可能发生，
但是通过捕食者而不是通过资源短缺。
相关主题 生态位（ B3） 种类竞争（ I2）
竞争的性质（ I1）
Related topics The niche (B3) Intraspecific competition (I2)
The mature of competition (I1)
If apparent competition occurs between two species,they
may try to escape the impact of the predator by escaping
from the vicinity of the other prey species into so-called
enemy-free space‘,Therefore,niche differentiation may
occur,but mediated by a predator rather than a resource
shortage.
Enemy-free space
J1 捕食的性质要 点捕食的定义 捕食可定义为摄取其他个体（猎物）的全部或部分为食。这一广泛的定义包括（ i）典型的捕食者，在袭击猎物后迅速杀死而食之；（ ii）草食者，只消费对象个体的一部分；（ iii）寄生者，与单一对象个体（寄生）
有密切关系，通常生活在寄主的组织中。
Predation can be defined as the consumption of all or part of
another individual (the prey),This wide definition thus
encompasses,(I)‘true predators‘,which kill their prey soon
after attacking them; (ii) grazers,which consume only part of
a prey individual; (iii)parasites,which live in very close
association with a single prey individual (the host),often
inside the host‘s tissues.
Key Notes
Defining
predation
J1 THE NATUES OF PREDATION
肉食者和草食者捕食者可以划分为（ i）消费植物组织的草食者，（ ii）
摄食动物组织的肉食者和（ iii）既摄食植物组织也摄食动物组织的杂食者。动物、植物食性的差异需要不同的生理和行为适应，从而导致肉食者与草食者世系之间反复的进行分歧。
泛化种和特化种捕食者随其摄取猎物的数量多少而变化，某些捕食者是特化种，而另一些是泛化种。一般来说，寄生者比典型捕食者更为特化、而草食者比肉食者更为特化。
Predators can be categorized as (i) herbivores which
consume plant tissue,(ii) carnivores which food in animal
tissue and (iii) omnivores which feed on both,The
difference between animals and plants as prey types
required different physiological and behavioral
adaptations,and has lead to repeated evolutionary
divergence between carnivorous and herbivorous lineages.
Carnivores and
herbivores
Predators vary in the number of species of prey they will
feed on,with some species being specialists,whilst others
are more generalist,Generally,parasites tend to be more
specialist than true predators and herbivores tend to be
more specialist than carnivores.
Generalists and
specialists
捕食者对猎物种群大小的影响捕食者和寄生者是否能够调节其猎物种群的大小呢？
这一问题并不像看上去的那么简单。有两种主要观点：
（ i）任一捕食者的作用，只占猎物种总死亡率的很小一部分，因此去除捕食者对猎物种仅有微弱效果；（ ii）
捕食者只是杀死了对象种中即将死亡的个体，所以最终对猎物种群大小没有影响。然而，在一些例子中确有明显证据表明捕食者对猎物数量有重要影响。
Do predators and parasites regulate the population size of
their prey? This is not as simple q question as it may
appear,There are two main issues,(I) the effect of any
one predator may only be a small component of the total
mortality causes affecting a prey species,so removal of
the predator will have only a minor effect; (ii) predation
may kill animals which were going to die anyway,so
there will be no impact on the final prey population size,
However,in a number of cases there is clear evidence that
predators have a considerable impact on prey numbers.
The impact of
predators on prey
population size
Lotka-Volerra
捕食者 -猎物模型
Lotka-Volterra捕食者 -猎物模型是描述捕食者与猎物间相互关系的一个简单的数学模型。这一模型做了三个简单化假设：（ i）相互关系中仅有一种捕食者与一种猎物；（ ii）如果捕食者数量下降到某一阈值以下，猎物数量就上升，而捕食者数量如果增多，猎物种数量就下降和（ iii）如果猎物数量上升到某一阈值，捕食者数量就增多，而猎物种数量如果很少，捕食者数量就下降。这一简单的模型做了一个有趣的预测：捕食者和猎物种群动态会发生循环，就像在自然的捕食者 -猎物种群动态中所观察到的那样。
The Lotka_Volterra predator-prey model is a simple
mathematical model representing the interaction
between predators and their prey,It makes three
simplifying assumptions,(i) there is only one predator
and one prey species involved in the interaction; (ii)
prey numbers increase if the number of predators falls
below a threshold and decrease if there are more
predators; and (iii) predator numbers increase if the
number of prey rises above a threshold and decrease
if there are fewer prey,This simple model makes an
interesting prediction,predator and prey populations
will tend to cycle,as is observed in natural predator-
prey dynamics.
Lotka-Volterra
predator-prey model
相关主题 出生率、死亡率和种群增长（ H2）
种群动态 ——波动、周期和混沌（ H4）
捕食行为和猎物反应（ J2）
寄生的性质（ K1） 寄生的动态（ K2）
Related topics Natality,mortality and population Predator behavior and prey
growth (H2) response (J2)
Population dynamics –fluctuations,The nature of parasitism (K1)
cycles and chaos (H4) The dynamics of parasitism K2)
J2 捕食行为和猎物反应要 点猎物收益率 面对两种类型猎物的选择时，捕食者要获得最佳捕获努力，就应该选择收益最大的猎物。真蟹和白脊 令的证据表明捕食者优先选择能使其在单位时间内获得最大能量的一定大小的猎物，而不是比该体积更大或更小的猎物。
鸟 鸟
Given a choice between two potential prey types,a
predator which is optimizing its effort should choose
the most profitable prey,Evidence from common shore
crabs and pied wagtails demonstrates that prey of a size
which return the greatest energy reward per unit time
are preferred over smaller and larger individuals.
Key Notes
Profitability of
prey
J2 PRED ATOR BEHAVIOR AND
PREY RESPNSE
猎物转换 依据猎物种数量的多少，捕食者有时会转换其选择而捕食某一特定的猎物种。这时捕食者主要捕食优势种猎物而大大忽略其他猎物。
猎物密度影响
——功能反应一般认为在高猎物密度下，捕食者的摄食率会增加，
然后随猎物饱和达到最大速度。这种关系称为功能反应，可能采用多种模式，传统上分为三种类型：功能反应 I,II和 III。
Predators may alter or?switch‘ their preference for a
particular prey species depending on the abundance of
that species,When this occurs,common prey are
consumed super proportionately whilst less common
prey are largely ignored.
Switching between
prey types
It is generally expected that at high densities of prey,a
predator‘s consumption rate will increase and then
flatten out as prey saturation occurs,this relationship
is termed the functional response and may adopt
different patterns,which can be stereotyped into three
classes,functional responses I,II and III.
The effect of prey
density – functional
responses
搜寻和处理 为得到食物，捕食者必须首先搜寻猎物，然后处理
（抓住、加工和吃掉猎物）。可以认为捕食者食谱的宽度是由泛化种对策与特化种对策之间的权衡决定的。
泛化种对策捕食者寻找多种猎物（相对容易），特化种对策捕食者寻找一类猎物，非常有效的处理它。最佳觅食理论假定进化会最优化动物行为以使其获得的能量效率最大，从而做出捕食者如何权衡搜寻与处理的预测。
To obtain food,a predator must first search for its prey
and then?handle‘ (catch,process and eat) it,Diet width
can be regarded as being determined by a balance
between a generalist strategy of searching for a wide
variey of prey (relatively easy) and a specialist strategy
of searching for one type of prey and handling that very
efficiently,Optimal foraging theory assumes that
evolution will have optimized predator behavior to
maximize the rate of energy gain and makes predictions
about how we should expect predators to balance
searching and handling.
Searching and
handling
异质性和猎物隐蔽处实验室捕食者 —猎物实验表明在一个单纯环境中，或
（ i）捕食者吃掉所有猎物个体，或（ ii）捕食者种群消亡而猎物存活。然而，如果环境更为复杂，则一些猎物个体可能在猎物避难所中摆脱捕食，从而出现捕食者 —猎物的共存。由于生境斑块在维持竞争种间共存中所起的作用（见 I1）推论，环境异质性很可能在允许捕食与猎物共存中具有关键的重要意义。
Predator-prey experiments in the laboratory indicate
that in simple environment,either (i) predators are able
to consume all prey individuals,or (ii) the predator
population becomes extinct and the prey survives,If,
however,the habitat is more complex some prey
refuges and coexistence between predators and prey
may occur,In corollary with the role of habitat
patchiness in maintaining coexistence between
competing species (see topic I1),environmental
heterogeneity is likely to be of critical importance in
allowing predators and prey to coexist.
Heterogeneity and
prey refuges
理想自由分布 捕食者并不单独对猎物的分布与密度做出反应 ——它们对与之竞争的捕食者的分布也会反应。捕食者趋向于聚集在最有利可图的斑块中，但捕食者之间的拥挤会降低斑块的有利度，直到移到另一块不太拥挤的斑块中去会更好。理想自由分布理论认为捕食者会在各分布区间移动，直到各区有利度相等。
Predators do not solely respond to the distribution and
density of prey – they may also respond to the
distribution of competing predators,Predators will tend
to aggregate in the most profitable patches,but
predator crowding will reduce the patch profitability
until it is better to move to another less crowded patch,
The ideal free distribution theory suggests that
predators should move among sites until profitability is
equal.
The ideal free
distribution
植物防御 植物以两种主要方式来保护自己免遭捕食：（ i）毒性与差的味道，和（ ii）防御结构。在植物王国已发现大量的多种化学武器来保卫植物免遭捕食和寄生者的进攻。这些次生性化合物或直接有毒，或可降低植物的食物价值，如降低动物肠道对植物叶组织蛋白的吸收。
防御结构在各种水平上都存在，从叶表面可陷住昆虫及其他无脊椎动物的微小绒毛，到可阻止哺乳类草食动物的大型针刺。经历过落叶的植物，其次生化合物水平及防御结构大小都会提高或“被诱导”。
相关主题 竞争的性质（ I1） 捕食的性质（ J1）
Related topics The mature of competition (I1) The nature of predation J1)
Plants defend themselves from predation in two main
ways,(i) toxicity and unpalatablity,and (ii) defensive
structures,There is a vast variety of chemical ammunition
found in the plant kingdom used to defend plants against
attacks from predators and parasites,These secondary
compounds may either be directly toxic or they may
reduce the food value of the plant,for example,by
reducing the availablity of the leaf tissue protein to the
animal gut,Defensive structures exist on a variety of
scales,from small hairs on the leaf surface which may trap
insects and other invertebrates,to large spines which deter
mammalian herbivores,Both the levels of secondary
compounds and the size of defensive structures may be
elevated or?induced‘ in plants that have suffered
defoliation.
Plant defense
K1 寄生的性质要 点寄生物的多样性寄生物是摄取其他生物的组织、与其寄主紧密相联而生的捕食者的子群。寄生物可以分为两大类（ i）微寄生物，在寄主体内或表面繁殖，（ ii）大寄生物，在寄主体内或表面生长，但不繁殖。主要的微寄生物有病毒、细菌、真菌和原生动物。寄生蠕虫和昆虫是重要的大寄生物。一大类昆虫大寄生物是拟寄生生物，它们在昆虫寄主身上或体内产卵，通常导致寄主死亡。
Parasites are a subgroup of predators (which consume the
tissue of another living organism) that live in close
association with their host,Parasites can be classified into two
broad groups,(i) microparasites,which multiply within,or on
the surface of,the host,and (ii) macroparasites which grow in
or on the host,but do not multiply,The main microparasites
are viruses,bacteria,fungi and protozoans,Helminth worms
and insects are important macroparasites,A large group of
insect macroparasites are parasitoids,which lay eggs in or on
the body of their insect host,and usually cause the death of
the host.
Key Notes
The diversity of
parasites
K1 THE NATURE OF PARASITISM
寄主对疾病的反应脊椎动物被微寄生物感染后产生强烈的免疫反应。这种反应主要有两种成分：（ i）细胞免疫反应，特定细胞直接攻击病原体细胞，和（ ii） B-细胞免疫反应，
使抗体量上升。初次被病原体感染后，免疫记忆对未来同样的侵袭产生快速反应，导致免疫。无脊椎动物和植物也可以抑制感染，但方式较简单，通常较少特化机制。免疫造成的潜在寄主减少，使微寄生物的繁荣 -和 -破产对策加强（见 K2）
传播方式 寄生物可以横向传播（在种群个体之间），或在少数情况下，纵向传播（从母体到后代）。横向传播或直接或间接，由传病媒介（如蚊子）或中间寄主做中介。
Parasite transmission can be either horizontal (among members
of a population) or,less commonly,vertical (passed from
mother to offspring),Horizontal transmission may either be
direct or indirect,mediated by a vector (e.g,a mosquito) or an
alternate host.
Modes of
transmission
In vertebrates,infection by microparasites results in a strong
immunological response,There are two components to this
response,(i) the cellular immune response,where specialized
cells directly attack pathogen cells,and (ii) the B-cell immune
response,which gives rise to antibodies,After the first infection
by a pathogen,immunological memory creates a raid response
to future attacks by the same organism,resulting in immunity,
Invertebrates and plants also may suppress infections,but by
less sophisticated,and usually less specific mechanisms,The
loss of potential hosts which immunity engenders accentuates
the boom-and-bust strategy of microparasites (see Topic K2),
Host response
to disease
复杂的生活史 许多寄生物在其生活史中不得不转换二或三种寄主。
对这种复杂的生活史有三种不同的解释：（ i）交替寄生是被寄生物感染的传病媒介（不适用于不可能成为传病媒介的不动寄主）；（ ii）出现最适生境利用，在这种环境中，不同寄主种是不同季节或不同生活史阶段的最佳资源；（ iii）这种模式起因于进化约束，因为寄生物在其生活史的某阶段中高度适应一种寄主，所以它们不能离开该寄主，即使在其他地方能获得更高的利益。
Many parasites obligately switch between two or three host
species in the course of their life cycle,Three different
explanations have been advanced to explain such complex
life cycles,(i) alternate hosts are vectors which have been
attacked by the parasite (this cannot apply to immobile
hosts which cannot be vectors); (ii)optimal habitat use is
occurring,where different species are the optimal resource
in different seasons,or for different life cycle stage; (iii) the
pattern is due to evolutionary constraint,as parasites
become highly adapted to one host for part of their life
cycle,they are unable to leave it even though the rewards
are higher elsewhere,
Complex life
cycles
相关主题 出生率、死亡率和种群增长（ H2） 寄生的动态（ K2）
捕食的性质（ J1）
社会性寄生物 ―社会性寄生物”与其寄主之间有一种完全不同的关系。
社会性寄生物不通过摄食寄主组织获益，而是通过强迫寄主提供食物或其他利益而获利。这种关系发现在杜鹃，它们将蛋下在别种鸟的巢中，让这种鸟饲育其幼鸟。这种关系还发现在一些蚂蚁种类，它们迫使其他种工蚁给它们的幼体食品或其他利益。
Related topics Natality,mortality and population The dynamics of parasitism (K2)
growth (H2) The mature of predation (J1)
A completely different form of relationship is found
between‘ social parasites‘ and their hosts,Social parasites
gain benefit from their animal hosts not by feeding on their
tissues but by coercing them to provide food or other
benefits,Such relationships are found in cuckoos which lay
their eggs in the nests of other bird species,which then
undertake the rearing of the young,and in some ant species
which coerce the workers of another species to provision
their brood.
Social parasites
K2 寄生的动态要 点寄生物 -
寄主动态脊椎动物寄主一般对寄生产生免疫。这些免疫寄主不能再被寄生物利用，因而易感种群的大小减少。这使疾病的传染力降低。然而，随着新的易感寄主加入种群（如新个体出生），疾病的传染力会再次增加。因此，传染病有循环的趋势，在新的易感个体增加时上升，在免疫水平上升时下降。当一种致病寄生物繁殖率下降时，传染力对易感个体加入的反应较慢，动态从两峰之间短间隔的明显的同步循环变为同步性减弱，
间隔加长，直到最后观察不到循环。
Vertebrate hosts commonly acquire immunity to parasites,
These immune hosts are no longer available to the parasites,
and the size of the susceptible population is reduced,This
results in a fall in the incidence of disease,However,as new
susceptible hosts enter the population (for example,by birth),
the disease will increase in incidence again,Thus,there is a
tendency of diseases to cycle,rising as the number of new
susceptibles increases and falling as the level of immunity rises,
As the influx of new susceptibles increases and falling as the
level of immunity rises,As the reproductive rate of a disease
falls,the response of disease incidence to the influx of
suscetibles is slower and the dynamics change from clear,
synchronous cycles with a short period between peaks to
reduced synchrony and longer periodicity until finally no cycles
are observable.
Key Notes
Parasite-host
dynamics
K2 THE DYNAMICS OF PARASITISM
寄主 ——
寄生物进化寄生物与其寄主间紧密的关联经常导致二者在进化上的相互作用，或协同进化。协同进化使寄主的防御机制提高，而给寄生物克服这些防御的通路 ——这叫做
“军备竞赛”。但是，寄主与寄生物之间的协同进化并不都是提高性的。例如，协同进化会降低寄生物的毒性。
The close association between parasites and their hosts often
results in evolutionary interactions,or coevolution,
Coevolution may give rise to defence mechanisms in the host
and routes to overcome these defences in the parasite – so
called?arms races‘,Not all coevolution between host and
parasite is escalatory,however,For example,coevolution may
lead to the reduction in the virulence of a parasite.
Host- parasite
evolution
微寄生物传染病模型微寄生物的繁殖率（ Rp）可表示为由一个感染寄主所传染的新个体数,Rp =βSd。如果 Rp小于 1，则病症传染力在寄主种群中下降，而如果 Rp大于 1，疾病传染上升。该模型可预测（ i）寄主死亡快速发生时降低毒性的进化，（ ii）转换寄主使寄生的适合度最大，（ iii）
对 某一寄生物来说有一寄主密度阈值，低于该阈值寄生物不能存活，和（ iv）易传染时间短的疾病不能在小种群中持续。
The reproductive rate of a microparasite (Rp ) can be
expressed as the number of mew cases that will arise from
an infected host,Rp =βSd,If Rp is less than one,then the
disease incidence is falling in the host population,whilst if
Rp is greater than one,the level of disease is increasing,
This model can predict (i) the evolution of reduced
virulence when host deaths occur rapidly,(ii) altered host
behavior to maximize parasite fitness,(iii) that there is a
threshold density of hosts for a given parasite,below
which the parasite will not survive,and (iv) that diseases
with short periods of infectivity should not persist in small
populations.
A model of
microparasite
disease
寄生物种群的异质性一些疾病是稳定的，而另一些进化了通过变异“逃离”
寄主防御的手段。人类“孩童时期”的疾病 ——麻疹、
腮腺炎、水痘等大部分局限于孩子，因为它们的抗原稳定。与此相对，寄生物如流感病毒、鼻病毒（普通感冒原）和沙门氏菌（ Salmonella）具有可经常加入的很多变异型。寄主因此要经常与变化的寄生物军队的进攻而进行战斗。
Whilst some diseases are stable,others have evolved
escapes‘ from host defences by variation,The
childhood‘ diseases of humans – measles,mumps
chickenpox etc,are largely restricted to children
because they are antigenically stable,In contrast,
parasites such as influenza,rhinoviruses (the cause of
the common cold) and Salmonella have multitudes of
strains which are constantly being added to,Hosts
therefore have a constantly varying army of attacking
parasites to contend with.
Heterogeneity in
host populations
寄生作为有性繁殖的原因：
,红皇后,
有性繁殖的代价高于无性繁殖，因为雄性不产后代，
所以种群增长慢。因此，一定存在一些可平衡利益。
据认为有性繁殖的主要利益是产生遗传变异，来对付寄生物普遍存在的和变化着的攻击。
相关主题 出生率、死亡率和种群增长（ H2） 寄生的性质（ K1）
捕食的性质（ J1） 生态学中的性（ N2）
寄主种群的异质性寄主种群内个体在被寄生物感染的风险上很少是均等的。个体的年龄、行为、健康状况、与被感染个体的接近程度以及特别重要的个体的遗传性易患病程度，
都会影响结果。
Related topics Natality,mortality and population The mature of parasitism (K1)
growth (H2) Sex in ecology (N2)
The mature of predation (J1)
Individuals within a host population are very rarely equally
at risk of being successfully attacked by a given parasite,
The age,behavior,state of health,proximity of the infected
individuals,and,of particular importance,the genetic
predisposition of an individual will all influence the
outcome.
Heterogeneity in
host populations
The costs of sexual reproduction are high compared to
asexual reproduction,as males produce no offspring,so
population growth is slow,Therefore,there must be some
balancing benefit,It has been suggested that the main
benefit of sex is to produce genetic variation to overcome
the ubiquitous and dynamic attack of parasites.
Parasites as a
reason for sex –
the
‘Red Queen’
L1 互利共生要 点互利共生和共生现象互利共生是不同种两个体间一种正的互惠关系，可增加双方的适合度。互利共生可以是共生性的，生物体以一种紧密的物理关系生活在一起。
专性互利共生 有些互利共生者，如地衣，是永久性成对组合，其中一方或双方不能独立生活。大多数共生者是专性共生，
还有一些非共生性的互利共生也是专性的，如蘑菇 -耕作蚁之间的互利共生。
Mutualism is a positive reciprocal relationship between
two individuals of different species which results in
increased fitness for both parties,Mutualism may be
symbiotic,in which the organisms live together in close
physical association.
Key Notes
Mutualism and
symbiosis
L1 MUTUALISM
Some mutualisms,such as lichens,are permanent
pairings in which one or both partners cannot lead an
independent life,Most symbioses are obligate,as are
some nonsymbiotic mutualisms,such as those formed by
fungus-farming ants.
Obligate
mutualism
兼性互利共生 互利共生的多数是非专性和机会性的。这些互利共生可能是散开的，包含有不同的物种混合，如许多传粉者与其传粉植物之间的互利共生。
传 粉异型杂交植物需要将其花粉转移到同种植物的柱头上，
并接受同种植物的花粉。一些植物种类靠风来传播花粉，如果植物生长在广大的植物种类单一的地方如草地和松林，这种传播方式会很有效。但是大多数开花的双子叶植物，依靠昆虫、鸟、蝙蝠或小型哺乳动物来传播花粉，作为交换，这些动物或以花蜜或以花粉本身为食。
The majority of mutualisms are nonobligatory and
opportunistic,They may be diffuse,involving a varying
mixture of species,as occurs between many pollinators
and their plants.
Facultative
mutualism
An out crossing plant needs to transfer its pollen to the
stigma of a conspecific plant,and receive pollen from a
conspecific,Some plant species rely on the wind to
achieve this,which can work acceptably well if plants
grow in large homogeneous stands of few species,as
occurs in grasslands and pine forests,However,in most
species of flowering dicotyledonous plants,insects,birds
bats or small mammals are employed to transfer pollen
from plant to plant,usually in exchange for either nectar or
pollen itself as a foodsource.
Pollination
种子扩散 大型种子无法有效的被风传布，除非靠水传布（如椰树的种子），或依靠动物来散布。啮齿动物、蝙蝠、
鸟和蚂蚁都是重要的种子扩散者。
防御性互利共生一些互利共生为其中一方提供对捕食者或者竞争者的防御。这种防御性互利共生的例子见于一些草和产生植物碱的真菌之间，以及许多种植物和蚂蚁之间。
Large seeds cannot be effectively wind-dispersed,and
unless dispersal by water (as occurs in the coconut palm)
occurs,such plants are dependent on animals for
dispersal,Rodents,bats,birds and ants are all important
seed dispersers.
Seed dispersal
A number of animal species rely to some extent on
mutualisms with mutualists which reside within their
bodies,Ruminants (deer and cattle) possess a multi-
chambered stomach in which bacterial and protozoan
fermentation take place,In some termites,which feed on
wood,the necessary breakdown enzymes are provided by
bacterial mutualists,Intracellular bacterial symbionts
which transform amino acids occur in a number of insect
groups,including aphids and cockroaches.
Symbiotic
mutualists within
animal tissues and
cells
动物组织或细胞内的共生性互利共生一些动物种类在某种程度上依赖于同生活在其体内的共生体间的互利共生。反刍动物（鹿和牛）拥有多室胃，在其中发生细菌和原生动物的发酵作用。在一些以木为食的白蚁中，必需的分解酶由细菌共生体提供。
在一些昆虫种类，包括蚜虫和蟑螂，存在转换氨基酸的细胞内细菌共生体。
Some mutualisms provide one partner with a
defense against predators or competitors,Examples
of such defensive mutualisms are found between
some grasses and alkaloid-producing fungi,and
between many plant species and ants.
Defensive
mutualisms
互利共生和进化互利共生可能起源于寄生物 -寄主和捕食者 -猎物之间的关系，或起源于没有协作或相互利益的紧密共栖物种之间。然后双方的进化变化（协同进化）导致双方从这种关系中获益，虽然也可能共生“恶化”，成为使一方受益、另一方受非平衡的剥削的寄生关系。互利共生的相互作用在多细胞动物进化过程的一些关键阶段中起着中心作用。高等生物的许多细胞器官，包括线粒体和叶绿体，被认为来自共生性细胞。
相关主题 竞争的性质（ I1） 寄生的性质（ J1）
Related topics The nature of competition (I1) The mature of parasitism (K1)
Mutualism and
evolution
Mutualism may have arisen form parasite-host and
relationships,or between closely coexisting species
with no cooperation or mutual benefit,Evolutionary
changes in both partners (coevolution) have then
resulted in both partners benefiting from the
relationship,although it is possible for mutualisms to
deteriorate‘ into unbalanced exploitation of one
partner to the benefit of the other – parasitism,
Mutualistic interactions have been central to number
of important steps in the evolution of multicellular
organisms,Many of the cell organelles of higher
organisms,including mitochondria and chloroplasts
are believed to be derived from symbiotic bacteria.
M1 生活史要 点生活史变异 生物的生活史是指其一生中生长和繁殖的模式。不同种类其生活史类型的变异是巨大的。一些种类能活成百上千年，一些个体身体巨大，而另一些则微小。一些生产许多小后代，而另一些生产后代数量较小，但个体较大。在关这些变异是如何进化而来的问题，是生态学的一个关键。
An organism‘s life history is its lifetime pattern of
growth and reproduction,The observed in the life
history patterns of different species is vast,Some
species live for hundreds or even thousands of years,
some grow to vast sizes whilst other are minute,Some
produce many,tiny offspring whilst others have few,
relatively large offspring,How these differences evolve
is a key question in ecology.
Key Notes
Lire history
variation
M1 LIFE HISTORY
能量分配和
,权衡,
让某一生物在出生后短期内达到大型的成体大小，生产许多大个体后代并长寿是不可能的。分配给生活史一方面的能量不能再用在另一方面，所以在不同生活史特性间进行“权衡”是不可避免的。
It is not possible for an organism to reach a large adult
size shortly after birth,produce many large offspring
and live to a great age,Energy allocated to one aspect
of life history cannot be spent in another,so?trade-offs‘
between different traits are inevitable.
Energy allocation
and trade-offs
r -选择和
к -选择
r-选择和 K-选择理论描述了两种明显的生活史对策，该理论陈述,r-选择种类适应使其种群增长率最大，而 к-
选择种类适应使其竞争性强。这样,r-选择种类发育快，
成体小，后代数量多但体积小，世代时间短。与此相反,к-选择种类发育慢，成体大，后代数量少但体积大，
世代时间长。尽管有些种类符合这种理论上的两分法，
但也有许多种不符合。由于具有更广预测性的更好的模型出现，该理论已过时了。
Two distinct life history strategies are described by г- and
к-selection theory,which states that г- selected species
are adapted to maximize the rate of increase of the
population size,whilst к-selected species are adapted to
be competitive,Thus,r-selected species have rapid
development,small adults,many and small offspring and
a short generation time,In contrast,к-selected species
have slow development,large adult size,few,large
offspring and long generation times,Although some
species fit this theoretical dichotomy,many do not,and
this theory is mow out-dated as better models have wider
predictive powers,
г- and к-selection
生 殖 价 年龄 x的个体的生殖价（ RVx）是该个体马上要生产的后代数量加上预期的其在以后的生命过程中要生产的后代数量。个体的生殖价在出生后必然会上升，然后随年龄老化而下降。个体间生殖价的差异提供了一个强有力的生活史对策预报器。
The reproductive value (RVx) of an individual of age x is
the number of offspring that individual is expected to
produce in the immediate future plus those expected over
its remaining lifespan,The reproductive value of an
individual inevitably rises after birth and falls towards old
age,The difference in reproductive values between
individuals provides a powerful predictor of life history
strategy.
Reproductive
values
生境分类 除 r-和 K-选择概念外，还存在多种方案划分生境，试图辩别一种连接生境与生活史的模式。生境可在生长与繁殖间利益平衡的基础上划分为“高繁殖付出”和
“低繁殖付出”生境。另一种可供选择的方法，“两面下注”考虑生境对不同生长期死亡率和繁殖力相关变化的影响，利用这种影响来预测最适生活史对策。
Grime的,CSR三角形”从植物生活史的观点，利用生境干扰（或稳定）程度及其对植物的严峻性来划分生境。
In addition to the concepts of г- and к-selection,there a
variety of schemes which classify habitats in an attempt to
discern a pattern linking habitats and life histories,Habitats
may be classified on the basis of the balance of benefits
between growth and reproduction,into?high-cost-of-
reproduction‘ and?low-cost-of-reproduction‘,An alternative
approach,?bet-hedging‘,considers the impact of the habitat
on the relative variability of mortality or fecundity for
different growth stages and uses this to predict optimal life
history strategies,Grime‘s?CSR triangle‘ classifies habitats
from a perspective of plant life history,using the degree of
habitat disturbance (or stability) and its severity to plants.
Habitat
classification
滞育和休眠许多生物在生活史的某一阶段会推迟发育，如种子滞育和马鹿胚胎的植入推迟。这种对策是为躲避不适宜环境的一种适应反应（如在严冬生产幼鹿或发育）。
当摄食或其他活动的利益受到限制时，个体也可进入降低代谢活动的时期，如长时间的冬眠或短时间的蛰眠。
Many organisms undergo a delay in development at
some stage in their life cycle,such as seed diapause or
implantation delay in a red deer embryo,This strategy
is an adaptive response to avoid unfavorable conditions
(such giving birth to young deer or germinating in the
midwinter),Individuals may also enter periods of
reduced metabolic activity such as long-term
hibernation or short- term torpor when the benefits of
foraging or other activities are limited,
Diapause and
dormancy
迁 移生物也可以通过移动到别处来躲避当地恶劣的环境。
迁徙是方向性运动，如燕子从欧洲到非洲的秋季飞行。
相反，扩散是离开出生或繁殖地的非方向性运动。迁移有三种，依据生物个体做的是（ i）反复的往返旅行，
（ ii）单次往返旅行，或（ iii）单程旅行。
Organisms may also avoid local harsh conditions by
moving to another location,Migration is directional
movement,such as the autumn flight of swallows from
Europe to Africa,Dispersal,in contrast,is a nondirectional
movement away from the birth or breeding site,There are
three categories of migration,depending on whether an
individual makes either (i) repeated return trips (ii) a single
return trip,or (iii) a one- way trip.
Migration
复杂的生活周期许多植物、真菌和动物具有复杂的生活周期，在生活周期中，个体采用根本不同的形态学性状（如毛虫 /蝴蝶，蝌蚪 /青蛙）或世代以一种可预测的方式彼此根本不同（如植物的单倍体 /双倍体世代交替，锈菌和蚜虫的有性 /无性世代交替）。为什么要采用这些复杂的生活史对策呢？在一些种类、不同的期或主要进行生长或主要进行扩散，而在其他种类，不同的期是为了最有效的利用不同的生境。
Many plants,fungi and animals have complex life
cycles,in which either individuals adopt radically
different morphological forms (e.g,caterpillar /
butterfly,tadpole / frog) or generations differ radically
from one another in a predictable fashion (e.g,haploid
/ diploid / alteration of generation in plants,sexual
/asexual generations in rusts and aphids),Why are
these complex strategies adopted? In some species,
different stages are mainly devoted to either growth or
dispersal,whilst in others different habitats are
optimally utilized in different stages.
Complex life cycles
衰 老 为什么生物个体变老后身体恶化，繁殖力和精力降低？
对这一问题有两个水平的答案。在机制水平上，由于毒物和自然辐射的影响，使细胞机器崩溃，从而引起衰老。但是，这不能是完全的原因 ——衰老的发生随种类不同变化很大。这说明进化影响或决定着衰老。
衰老的进化模型认为，或者（ i）一个影响较老个体的有害突变，比影响年轻个体的有害突变，受到更弱的选择对抗，或者（ ii）对早期繁殖有益的基因在生命晚期有恶性影响。
相关主题 种群和种群结构（ H1） 竞争的性质（ I1）
寄生的性质（ K1）
Related topics Populations and population The mature of competition (I1)
structure (H1) The nature of parasitism (K1)
Senescence Why do individuals deteriorate as they grow old,with resultant reduced fecundity and vigor? There are two levels
of answer to this question,At the mechanistic level,
senescence is caused by the breakdown in cellular machinery
to the effects of toxins and natural radiation,However,this
cannot be the complete story – the onset of senescence varies
hugely between species,This suggests evolution affects or
determines senescence,Evolutionary models of senescence
suggest that either (i) a mutation deleteriously affecting older
individuals will be selected against more weakly than one
affecting younger individuals,or (ii) there are genes which
benefit early reproduction which have deleterious effects
later in the lifespan.
N1 社群、合作和利他行为要 点合 作 许多动物，个体间有互利合作。这种合作可以是暂时性的（如共同猎食、关怀后代），或者是长久性的，
在一生中都保持着（如蚂蚁的群体，或一对缄默的天鹅）。
集群 ——好处 许多动物有集群，如椋鸟群、鲱鱼群、狮子群。集群给动物带来好处：逃避捕食动物、找食物和捕捉受围困的或大个的猎物。
In many animal species,individuals cooperate for their
mutual benefit,This cooperation can be temporary e.g,
(for hunting or offspring care),or permanent,lasting the
individual (e.g,an ant colony,or a pair of mute swans).
Key Notes
Cooperation
Many species of animals form groups,such as flocks
of starlings,shoals of herring or prides of lions>being
in a group gives an animal some advantages,avoidance
of predation,location of food and catching elusive or
large prey.
Grouping - benefits
N1 SOCIAL GROUPS,
COOPERATION AND ALTRUISM
集群 ——代价 作为集群的一员也有弊处：增加竞争食物的强度、更易引起捕食者的注目、提高感染疾病的风险。
利他行为 利他行为出现在：当一个个体行为导致另一个适合度增加，同时以其牺牲自身存活或产后代为代价。例如真社会性的蚂蚁群体中不育的工蚁，它们牺牲自身生殖的机会，代之以对其母后生殖的支持。这意味着，
利他主义者积极地减少其适合度。利他行为看起来似乎是矛盾的，然而，如果利他行为者与受惠者具有亲缘关系，这种对策可以使利他行为者有更多的基因遗传给下一代。
There are also costs of belonging to a group,increased
competition for food,increased conspicuousness to
predators,increased risk of disease.
Grouping – costs
Altruism occurs when an individual causes an increase in
the fitness of another individual of the same species at a
cost to its own survival or offspring production,An
example is the sterile worker in a eusocial ant society,
which sacrifices its opportunity of reproducing and instead
supports its mother‘s reproduction,This appears
paradoxical,as it implies that the altruist is actively
reducing its fitness,However,if the altruist is related to the
beneficiary,this strategy may result in more of the
altruist‘s genes passing to the next generation.
Altruism
真社会性的群体有一类动物种具有生殖分工，表现出极端的社会生活类型：一些个体放弃生殖（常常称为工蚁或工蜂），
另一些则是能生殖的（有性的，如蚁后和蜂王）。此类社会群仅仅出现在具长刺的膜翅目昆虫，如蚂蚁、
蜜蜂和胡蜂。
相关主题 种内竞争（见 I2） 生态学中的性（见 N2）
Related topics Intraspecific competition (I2) Sex in ecology (N2)
Eusocial society A select group of animal species display an extreme
form of sociality,in which there is a reproductive
division of labor,some individuals (usually called
workers‘) forego reproduction,whilst others are fertile
(?sexuals‘ such as queens),This type of society is only
common among a group of insects in the order
Hymenoptera equipped with a sting – ants,bees and
wasps.
N2 生态学中的性要 点性 性是植物和动物中广泛分布的现象，性有一系列生态后果。性在进化上的重要性是由于它产生遗传变异，
它在生态学上的重要性则是因为不同性别的生物其行为不同。两性之间的区别是由于它们对后代发育的能量投资不对称性而产生的。
Sex is a widespread phenomenon,found in plants and
animals,which has a number of ecological consequences,
Sex is evolutionarily important as it generates genetic
variation,and ecologically important because the different
sexes behave differently,The difference between sexes
arises from the asymmetry in the energy invested in
offspring development.
Key Notes
Sex
N2 SEX IN ECOLOGY
近交的代价 当亲缘相近的个体进行亲繁殖时，“交近”就出现了。
近交引起（ i）近交衰退（它使后代的适合度降低）和
（ ii）增加遗传纯合性（它降低了对于环境变化产生进化适应的可能性，而增加了灭绝的可能性）。许多物种具有防止或减少近交的机制。
自体受精 自体受精是雌雄同体的个体同时产生雌雄配子。对于营固着生活和运动能力很弱的生物，例如植物，它们不能主动地寻找配偶，自我兼容性是确保其不发生异体受精的一种方法。单一物种也有按环境和隔离水平而从自体受精转为异体受精的。
When closely related individuals interbreed,?inbreeding‘
occurs,which gives rise to (i) inbreeding depression (which
causes a reduction in offspring fitness) and (ii) increased
genetic homozygosity (which reduces the possibility of
evolutionary adaptation to a changing environment,and
increases the possibility of extinction),Many species have
mechanisms that prevent or curtail inbreeding.
The costs of
inbreeding
Self-fertilization involves male and female gametes
produced by the same,hermaphrodite individual,Self-
compatibility is a means by which sessile and less mobile
organisms‘ such as plants,that are unable to actively seek
mates,insure against failure to cross=fertilize,A single
species may switch from self=fertilization to cross-
fertilization depending on the environment and level of
isolation.
Self-fertilization
有性和无性生殖有性生殖重组了来自双亲的基因组，产生遗传上变化的配子和后代。这种高水平遗传变异的维持增加了对疾病的抵抗力，允许有适应不可预测环境条件的能力。
相反，无性生殖不产生遗传变异，但可以视为是对可预测环境条件的适应。
交配体制 动物，特别是脊椎动物，其交配的社会结构是重要的生态特征。一个雄体和一个雌体形成配偶，或者仅在繁殖季节，或者直到其中有一个死亡，这是单配制
（ monogyny）。当一个雄体与多个雌体交配，就出现了一雄多雌制（ polygyny）；当出现相反情况（很少见），即一个雌体具有多个雄体的交配群，就叫做一雌多雄制（ polyandry）。
Sexual reproduction recombines the genomes of the parents
producing genetically variable gametes and offspring,This
maintenance of high levels of genetic variation enhances
disease resistance and allows adaptation to unpredictable
environmental conditions,In contrast,asexual reproduction
does not generate genetic variation but can be seen as an
adaptation to predictable environmental conditions.
Sexual versus
asexual
reproduction
The social structure of mating in animals,and particularly in
vertebrates,is an important ecological parameter,
Monogamy is where one male and one female form a pair
bond,either for a breeding season,or until one dies,Where
one mal mates with a number of females,polygyny occurs,
whilst the opposite situation (which is rarer) where one
female has a mating group of a number of males is known
as polyandry.
Mating systems
性 比 性比是种群中雄体对雌体的比率，通常接近于 1雄：
1雌。但是，不等的消耗、拥挤的配偶竞争也可能使性比偏离。
性 选 择 性选择导致形成像孔雀之尾、雄苇莺动听的歌唱、
雄鹿的叉角等特征。交配竞争中生殖成效的不同导致性选择。
相关主题 种群和种群结构（见 H1） 遗传变异（见 O1）
Related topics Populations and population structure (H1) Genetic variation (O1)
Sex ratio
The sex ratio is the ratio of males to females in a population,
and usually is close to 1 male,1 female,However,unequal
costs,crowding and mate competition can bias the sex ratio.
Sexual selection
Sexual selection causes such features as the peacock‘s tail,
the elaborate song of the male reed warbler and the antlers
of the male stag,Sexual selection is caused by differences in
reproductive success due to competition for mates.
O1 遗传的变异要 点基因和等位基因基因是带有可产生特定蛋白的遗传密码的 DNA片段。
一个基因可有许多等位基因，而个体可有纯合或杂合的基因型。表达的表现型取决于等位基因是显性的、
隐性的还是共显性的。种群中存在的所有基因组和等位基因叫做基因库。
Genes are pieces of DNA which contain the genetic code
necessary to produce a specific protein,A gene can have
many alleles and individuals can have a homozygous or
heterozygous genotype,The phenotype expressed depends
on whether alleles are dominant,recessive or codominant,
The total set of genes and alleles present in a population is
known as the gene pool,
Key Notes
Genes and alleles
O1 GENETIC VARIATION
测定遗传变异 种群和物种内的遗传变异可直接由 DNA或蛋白（别构酶）变异来估计。蛋白或 DNA片段可通过凝胶电泳分离，呈现可刻划的带来决定个体的基因型。对个体
DNA的详细调查产生了一种独特的遗传指纹，对建立父子关系很有用。
多 型 多型指的是种群中等位基因的存在。一个种群或物种可能颜色是多型的，如蜗牛，或者一些生化特性是多型的，如植物的毒性。一些多型可能是由自然选择保持下来的，但其他是由于许多基因控制多型性状的结果。
polymorphism The term polymorphism refers to the presence of alleles in a
population,A population or species may be polymorphic for
color,as in snails,or for some biochemical function,as in
plant toxicity,Some polymorphisms are maintained by
natural selection,but others appear to result from the effect of
many genes controlling the polymorphic character.
Genetic variation within populations and species can be
estimated directly from the DNA or from protein (allozyme)
variation,Proteins or DNA fragments are separated by gel
electrophoresis to give bands that can be scored to determine
the genotype of individuals,Detailed investigation of the
DNA of individuals yields a unique genetic fingerprint,
useful for establishing paternity,
Measuring genetic
variation
遗传漂变 遗传漂变是基因频率的随机变化，仅偶然出现。在小种群中，遗传漂变更明显。基因频率“漂离”起始值，
增加、减少或上下波动。发生遗传漂变是因为在个体、
产生后代的合子以及繁殖前死亡的个体中都有偶然要素。基因频率的随机变化导致来自种群的遗传变异的固定和逐渐丧失。
遗传瓶颈 当种群数量突然减少时，基因频率也会发生变化，总的遗传变异下降。瓶颈发生的时候，小种群的遗传漂变导致遗传变异丧失。尽管种群数量可以恢复，遗传变异在以后许多代仍会保持低水平。
Genetic drift Genetic drift is a random change in gene frequency arising through chance alone,It tends to be more apparent in small
populations allele frequencies drift away from their starting
values,increasing,decreasing or fluctuating up and down,It
occurs because there is an element of chance in which
individuals and which gametes will produce offspring and which
individuals will die before reproducing,Random changes in
allele frequency can lead to fixation and the progressive loss of
genetic variation from the population,
Genetic
bottleneck
When a population undergoes an abrupt contraction in numbers,
this is accompanied by a change in gene frequencies and a
decline in the total genetic variation,Genetic drift in the small
population during the bottleneck results in the loss of genetic
variation,Although population numbers may recover,genetic
variation will remain low for many generations.
建立者效应 建立者效应描述由一个或几个个体建立新种群，导致低水平的遗传变异和在亲本种群中稀少的等位基因的经常不成比例的数量。人类中特定遗传病的高发病率可归因于建立者效应。
相关主题 适应（ B1） 稀有物种、生境损失和灭绝（ V1）
Related topics Adaptation (B1)
Rare species,habitat loss and extinction (V1)
Founder effect This term describes the establishment of a new population by
one or a few individual(s),resulting in low levels of genetic
variation and often a disproportionate number of alleles that
are rate in the parent population,In human populations the
high incidence of certain genetic diseases can be traced to
founder effects.
O2 物种形成要 点繁殖种的概念 繁殖种的概念，集中在如下思想：物种延续并保持其遗传的完整性和独特性是因为不进行异种杂交。生物种概念和识别种概念都根据相互杂交定义种。本观点与实际的物种定义不同的是后者以明显的形态学性状为基础。
基 因 流 基因流描述的是基因在种群内通过相互杂交、扩散和迁移进行的运动。高基因流使种群遗传上彼此相似。
受到限制的基因流使种群间发生分化。
The reproductive species concept focuses on the idea that
species exist and maintain their genetic integrity and
distinctness because they do not interbreed,The biological
species concept and the recognition species concept both define
species in terms of interbreeding,His view contrasts with the
practical definition of species on the basis of distinguishing
morphological characters.
Key Notes
Reproductive
species concept
O2 SPECIATION
Gene flow describes he movement of genes among populations
through interbreeding,dispersal and migration,High gene flow
causes populations to become genetically similar to one another,
Restricted gene flow allows differentiation to occur among
populations.
Gene flow
生物种的概念 生物种概念认为种是一组可以相互杂交的自然种群，
它们与其他种群间具有繁殖隔离。该概念将没有明显形态学差别的种群分成分离的姊妹种，因为它们不能彼此交换基因。生物种由繁殖隔离机制来保持。
识别种的概念 识别种的概念定义种是一组具有共同的交配识别系统
（ SMRS）的个体。交配识别系统包括交配的所有方面，
如繁殖器官和配子的兼容性、求偶鸣叫、行为和仪式。
该种定义强调将种保持在一起的因素。
This concept views species as a group of interbreeding natural
populations that are reproductively isolated from other such
groups,It allows populations that are indistinguishable
morphologically to be classified as separate,sibling species
because they do not interchange genes,Biological species are
maintained by reproductive isolating mechanisms.
Biological species
concept
The recognition concept views a species as a group of
individuals with a common Specific Mate Recognition System
(SMRS),The SMRS consists of all aspects of mating such as
compatibility of reproductive organs and gametes,courtship
song and behavior and pheromones,This species definition
emphasizes the factors that keep species together,
Recognition
species concept
异域性物种形成与原来种由于地理隔离而进化形成新种，为异域性物种形成。异域性物种形成最易发生在边缘隔离、处在种分布区的极端边缘的小种群。小的非典型种群与极端环境条件的混合作用可产生迅速而广泛的遗传重组
（遗传革命），从而导致物种形成。
邻域性物种形成邻域性物种形成发生在分布区相邻，但分布区内不同地点环境（如气候）条件不同的种群。如在环形种中那样，可发现中间杂种，但包括的很大的距离使两种类型不能完全混合。
Allopatric speciation occurs when the new species evolves in
geographic isolation from the parent species,It may take place
most readily in peripheral isolates,small populations at the
extreme edge of a species range,The combined effect of a
small atypical population and extreme environmnental
conditions can cause rapid and extensive genetic
reorganization (a genetic revolution) leading to speciation.
Allopatric
speciation
This form of speciation occurs where the speciating
populations are contiguous but subject to different
environmental (e.g,climatic) conditions in different parts of
the range,Intermediate hybrids are found,as in ring species,
but the large distances involved prevent the two types from
merging completely.
Parapatric
speciation
相关主题 适应（ B1） 遗传变异（ O1）
同域性物种形成同域性物种形成可能发生在没有地理隔离，但具有宿主选择差异、食物选择差异或生境选择差异的种群。
同域性物种形成是否发生尚有争议，尽管已观察到植食性昆虫宿主选择的快速变化。植物可以通过多倍体进行同域性物种形成。
Related topics Adaptation (B1) Genetic variation(O1)
Sympatric
speciation
Sympatric speciation may occur where there is no
geographical separation between the speciating
populations of habitat preference,Whether sympatric
speciation happens at all is a contentious issue,although
rapid changes in the host preference of phytophagous
insects has been observed,Plants can undergo sympatric
speciation through polyploidy.
P1 组成成员和过程要 点生态系统的概念
1935年 Tansley提出生态系统的概念，最初的定义包括一个定义的空间中所有的动物、植物和物理的相互作用。近代生态学家更倾向于从能（量）
流、碳流或营养物流来考虑生态系统。
The ecosystem concept was proposed by Tansley in 1935,
and was originally defined to include all the animals,plants
and physical interactions of a defined space,Modern
ecologists tend to think of ecosystems in terms of energy flow,
carbon flow or nutrient cycles,
Key Notes
The concept the
ecosystem
P1 COMPONENTS AND
PROCESSES
生态系统成分 单位面积中活有机体的身体构成了生物量（ biomass）
的现存量（ standing crop）：单位地（或水）面积的有机体的质量，通常以能量或干有机质为单位（例如 t/ha）
陆地群落大部分生物是植被。群落初级生产率是初级生产者植物所生产的单位面积生物量的速率。通过光合作用固定的总能量是总初级生产量（ GPP），其中一部分从群落丢失于呼吸作用（ R）。 GPP与 R之差称为净初级生产量（ NPP），它代表了新生物量的产生速率，
并可供异养生物（细菌、真菌和动物）消费之用。被异养生物生产的生物量叫做次级生产量。
The bodies of living organisms within a unit area constitute
a standing crop of biomass,the mass of organisms per unit
area of organisms per unit area of ground (or water),usually
expressed in units of energy or dry organic matter (e.g,tons
ha-1),The great majority of biomass in a terrestrial
community I is the rate at which biomass is produced per
unit area by plants,the primary producers,The total fixation
of energy by photosynthesis is referred to as gross primary
productivty (GPP) of which a proportion (R) is lost form the
community as respiration,The difference between GPP and
R is known as net primary productivity (NPP) and
represents the rate of production of new biomass that is
available for consumption by heterotrophic organisms
(bacteria,fungi and animals),The production of biomass
by heterotrophs is called secondary production.
Ecosystem
components
生态系统与热力学定律热力学第一定律说明，能量既不能被创造，也不能被破坏。热力学第二定律说明，每一次“转换都导致系统的自由能的减少”。因为能量转换不可能 100%的有效，因此异养生物的能量较少，必然比它们所吃的植物更少。生态相互作用的复杂性意味着，以这些热力学定律为基础去构建用于预测的数学模型是不可能的。
The first law of thermodynamics states that energy can
neither be created nor destroyed,The second law of
thermodynamics states that every transformation results in a
reduction of the free energy of the system,Because energy
transformation cannot be 100% efficient (from the second
law),heterotrophs must have less energy,and must therefore
be rater than the plants they feed on,The complexity of
ecological interactions means that it is not possible to
construct predictive mathematical models of living systems
based on these laws of thermodynamics.
Ecosystems and
the laws of
thermodynamics
转换效率 净初级生产力通过营养级流动的比例，决定于能量从一级到下一级的利用、通过途中的转化效率。正是三类转换效率的全部知识，是预测能量流动格局的全部要求，那就是消费效率（ CE）、同化效率（ AE）和生产效率（ PE）。消费效率是指一个营养级的有效总生产力（ P n-1）中，后一营养级成员实际消费（被吃掉）
部分（ I n）所占的百分比。同化效率是指一个营养级的消费者吃入消化道的食物能量（ In）中，被同化而穿过消化道壁、并成为参加生长或用于作功的有效能量
（ A n）所占的百分比。生产效率是指被同化的能量中
（ A n），加入到新生物量（ P n）所占的百分比。剩留下来的完全以呼吸热量而损失于群落。
The proportion of net primary production that flows through
trophic levels depends on transfer efficiencies in the way
energy is used and passed from one step to the next,A
knowledge of just three categories of transfer efficiency is all
that is required to understand the pattern of energy flow,These
are consumption efficiency (CE),assimilation efficiency (AE)
and production efficiency (PE),Consumption efficiency is the
percentage of total productivity available at one trophic level
(Pn-1) that is actually consumed (ingested) by a trophic
compartment one level up (In),Assimilation efficiency is the
percentage of food energy taken into the guts of consumers in a
trophic compartment (In) which is assimilated across the gut
wall (An) and becomes available for incorporation into growth
or used to do work,Production efficiency is the percentage of
assimilated energy (An) which is incorporated into new
biomass (pn),The remainder is entirely lost to the community
as respiratory heat.
Transfer
efficiencies
通过群落的能流如果净初级生产量和 CE,AE和 PE是已知的值，那么运用模型预测不同群落各个营养级的能流途径是可能的。
从这种有野外数据支持的模型研究得到了一个有意义的发现，即分解者系统是非常重要的。有普遍意义的是，在状态稳定的群落里，动物呼吸所丢失的被 NPP所平衡，所以现存生物量保持一样的水平。
相关主题 初级和次级生产力（见 P2） 群落、结构和稳定性（见 Q1）
食物链（见 P3） 群落格局、竞争和捕食（见 Q3）
Related topics Primary and secondary production The community,structure and
(P2) stability (Q1)
Food chains (P3) Community patterns,competition
and predation (Q3)
Energy flow through
a community
Given that specified values can be obtained for not
primary production and CE,AE and PE,it is possible to
predict,using models,the pathway of energy flow at
different trophic levels for different communities,From
such modeling studies,which are supported by field data,
the most significant finding is the overwhelming
importance of the decomposer system,Overall,in a steady
state community,losses through animal respiration
balance NPP so that standing crop biomass remains the
same.
P2 初级和次级生产力要 点初级生产力全球陆地的净初级生产力大约为 120× 10 9 t / a干物质，
而海洋的大约为 50 × 10 9 t / a干物质。这种生产力在地球上分布是很不均匀的。最富有生产力的系统出现在沼泽、湿地、河口湾、珊瑚礁和耕田。生产力随离赤道距离增大而降低，它表明温度与辐射的重要性。
Global net primary productivity is approximately 120× 109
tons fry weight per year on land,and 50× 109 tons per year in
the sea,This productivity is very unevenly distributed across
the Earth,The most productive systems are found amongst
swamp and marshland,estuaries,reefs and cultivated land,
Productivity decreases moving away from the equator,
indication the importance of temperature and radiation.
Key Notes
Primary
production
P2 PRIMARY AND
SECONDARY PRODUCTION
生产力对生物量的关系通过生产力（ P）与现存生物量（ B）之比，可以把群落生产力与产生它的现存量联系起来。对于森林，所得到的 P,B比率（即每年每公斤现存量所生产出的公斤数）平均为 0.042，其他陆地系统是 0.29，而水体群落是 17.0。考虑 P,B比率的另一种选择是以活组织的重量确定的生物量，它将缩小群落之间的这些大的区别。当然，精确测定活的生物量比例是很困难的事。
Community productivity can bi related to the standing crop
that produces it by comparing the ratio of productivity (P) to
standing crop biomass (B),The resulting P:B ratios (I.e kg
produced year-1 kg-1 standing crop) average 0.042 for forests,
0.29 for other terrestrial systems,and 17.0 for aquatic
communities,An alternative way of looking at P:B ratios
would be to define biomass in terms of weight of living tissue,
which would reduce these large differences between
communities,However,accurate measurement of the
proportion of biomass alive is difficult.
Relationship of
productivity to
biomass
次级生产力 次级生产力的定义是异养有机体的新生物量的生产速率。异养生物如动物、真菌，要求能量丰富的有机分子。异养生物的次级生产力必然地依存于初级生产力。
一般说来，在牧食者系统中，次级生产力是群落营养结构中，依存于消费活植物生物量的那一部分，在数量级少于植物生产力，从而形成了金字塔结构。然而也有例外。
Secondary production is defined as the rate of production of
new biomass by heterotrophic organisms,Heterotrophs are
organisms,such as animals and fungi,with a requirement
for energy-rich organic molecules,Secondary production by
heterotrophs is inevitably dependent on primary
productivity,Generally,in grazer systems,that part of the
trophic structure of a community which depends on the
consumption of living plant biomass,secondary
productivity is an order of magnitude less than primary
production resulting in a pyramidal structure,However,
there are exceptions to this.
Secondary
production
相关主题 太阳辐射与植物（见 F1） 组成成员和过程（见 P1）
植物与消费者（见 G2） 食物链（见 P3）
物质与能量的关系能量一旦转化为热，它就不再能被有机体用于作功或合成生物量的燃料。热损失到大气中，再也不能进入再循环。地球上生命所以能够存在，正是由于太阳辐射每天都提供着新鲜的可用能量。相反，像碳一样的营养物，就能被再利用。构成生物量基块的化学营养物可以被利用，以临界的特征在再循环着。与太阳辐射的能量不同，营养物的供应不是不会改变的。如果植物及其消费者没有被最后分解掉，营养物的供应将会耗尽，地球上的生命也将终止。
Related topics Solar radiation and plants (F1) Components and processes (P1)
Plants and consumers (G2) Food chains (P3)
The relationship
between matter and
energy
Once energy is transformed into heat,it can no longer be
used by living organisms to do work or to fuel the
synthesis of biomass,the heat is lost to the atmosphere and
can never be recycled,Life on Earth is possible because a
fresh supply of solar energy is made available every day,
In contrast,nutrients such as carbon can be reused,
Chemical nutrients,the building blocks if biomass,can be
used again,and recycling is a critical feature,Unlike the
energy in solar radiation,nutrients are not in unalterable
supply of nutrients would become exhausted and life on
Earth would cease.
Ｐ 3 食物链要 点营养物流 自养生物同化无机资源，生成有机分子的组件，这些组件成为异养生物的资源，后者又后为另一个消费者的资源。在这种食物链的每一个连接，我们能够辨别出通向下一个营养级的三条途径：分解、寄生和捕食。
消费者可能是泛化种（多食性的），吃广范围的猎物种，或者是特化为吃一个或一组有密切关系的种（单食性的）。
Autotrophic organisms assimilate inorganic resources into
packages of organic molecules,There become the resources for
heterotrophs which then become a resource for another
consumer,At each link in this food chain we can recognize
three pathways to the next trophic level,decomposition,
parasitism and predation,Consumers may be generalists
(polyphagous),taking a wide variety of prey species or may
specialize on single species or a range of closely related species
(monophagous),
Key Notes
Pathways of
nutrient flow
P3 FOOD CHAINS
营养级间的相互作用生态系统的一个特征是：占据其各个营养级的种数及种的性质。一个营养级的成员与邻近营养级的成员之间的相互关系可以用食物链来描述。食物链是连接吃与被吃的链，例如，食肉动物到它的最后的植物食物。
任何生态系统都有许多食物链，并可以组成食物网。
生态系统在能量 -营养物网的模式上有很大的变化。
A characteristic of an ecosystem is the number and
nature of the species that occupy its various trophic
levels,The relationship between constituents of one
trophic level and constituents of adjacent trophic levels
may be described by a food chain,This is a chain of
eating and being eaten that connects,for example,
carnivorous animals to their ultimate plant food,Many
food chains exist in any given ecosystem and van be
combined into food webs,Ecosystems vary considerably
in the pattern of their energy-nutrient webs.
Interactions
between trophic
levels
下行或上行 曾经有过辩论，地球是绿色的、长满植被的，这是因为食草动物被其捕食者所调节（下行控制,top-down
control），而所有别的营养级都是被资源竞争所调节的
（上行控制,buttom-up control）。这个简单的模型是吸引人的，但是其价值是值得怀疑的。由于植物有防御，食草物种在它们所吃的植物组织的范围方面是受到很大限制的；因此，即使世界是绿色的，它们也可能受到竞争的限制。不仅如此，植物大体上并不受能量的限制，但却受到空间限制，所以任何被食草动物清出的空间，都为更多的植物开放的机会。
Top-down or
bottom-up?
It has been argued that the earth is green and vegetated
because herbivore numbers are regulated by their predators
(top-down control),whilst all other trophic levels are
regulated by competition for resources (bottom-up control),
This simple model is attractive but of doubtful value,
Herbivore species are highly constrained in the range of
plant tissue they can eat,due to plant defences,and hence
may be level,plants are not energy-limited but space
limited,so any space cleared by herbivory opens
opportunities for more plants.
相关主题 捕食的性质（见 J1） 初级和次级生产力（见 P2）
捕食行为和猎物反应（见 J2）群落格局、竞争的捕食（见 Q3）
群落、结构和稳定性（见 Q1） 组成成员和过程（见 P1）
寄生的性质（见 K1）
Related topics The mature of predation (J1) Primary and secondary production
Predator behavior and prey (P2)
response (J2) The community,structure and
The nature of parasitism (K1) stability (Q1)
Components and processes (P1) Community patterns,competition
and predation (Q3)
Q1 群落、结构和稳定性要 点群 落 群落（ community）是在相同时间聚集在同一地段上的许多物种种群（ species populations）的集合。它的特性是由个体之间的相互作用如竞争（ competition）和寄生
（ parasitism）决定的。群落也能够从更广阔的角度和物种多样性（ species diversity）、食物网（ food-webs）、
能量流（ energy flow）和同资源种团（ guilds）中种间的相互作用来观察它的特性。
The community is an assemblage of species populations that
occur together in the same place at the same place at the
same time,It has properties determined by the imteractions
among individuals such as competition and parasitism,The
community can also be viewed from the broader perspective
in terms of species diversity,food-webs,energy flow and the
interactions among guilds of species.
Key Notes
The community
Q1 THE CPMMUNITY,STRUCTURE
AND STABILITY
群落结构一个群落的物种多样性取决于群落含有的不同种的数量即种丰富度（ the species richness）和种多度的均匀性（ the evenness of species abundance）。多样性指数
（ diversity indices）可以通过这两个因子计算出来。表达种丰富和种均匀度综合的另一种方式是通过种的相对多度对种的顺序作图。多样性能够在局域群落
（ local community）、地区（ region）和最广阔的地理尺度（ geographic scale）（如大陆）三个不同的空间尺度上测算它。这样就产生了 a,β和 Υ多样性。
The species diversity of a community depends on the number
of different species it contains (the species richness) and the
evenness of species abundance across species,Diversity
indices can be calculated to take into account both of these
factors,Another way of representing species richness and
evenness together is to plot the relative abundance of species
against rank order of species abundance,Diversity can be
measured over the three different spatial scales of the local
community,the region and the broadest geographic scale (e.g,
the continent),This yields alpha (α)-,beta (β)-and gamma
(γ)-diversity,
Community
structure
群落边界 群落不会突然中断，而是逐渐的过渡到其他群落，因为各个物种是逐渐受到它们的环境耐受力限制的。这一点可以通过梯度分析来得到证明，梯率分析重点在于物种分布重叠区域。分类和排序的统计方法允许群落的边界在这个连续体上重叠。分类技术分出了生态学上不同的物种或地段，获得了客观等级。排序并不是企图勾画出边界，而是根据它们在分布上的相似性而勾画出物种集团或地段。
Communities do not end abruptly but grade into one
another as individual species encounter the limits of their
environmental tolerance,This can be demonstrated
through gradient analysis,which focuses on the
overlapping distributions of individual species,The
statistical methods of classification and ordination allow
community boundaries to be superimposed on this
continuum,Classification techniques separate
ecologically different species or sites yielding objective
classes,Ordination does not attempt to draw boundaries
but groups species or sites according to how similar they
are in their distributions,
Community
boundaries
同资源种团 同资源种团是许多占据相似生态位的物种组合的集团；
如以阔叶树为食物的许多昆虫就形成一个同资源种团。
一些研究已经表明，在一个群落内的某些同资源种团中的总物种的比例是不变的。这就表明也许有某一共同的“规则”在统治着群落结构。
Guilds are groups of species that occupy similar niches;
for example,insects feeding on broad-leaved trees form
one guild,Some studies have found constancy in the
proportion of total species in certain guilds within a
community,This indicates that there may be certain
common?rules‘ governing community structure.
Guilds
群落的复杂性、
多样性和稳定性稳定性有两个组成成分 ——恢复力（ resilience）和抵抗力（ resistance）。这两个指标描述了群落在受到干扰后的恢复能力和抵御变化的能力。复杂性被认为是决定群落恢复力和抵抗力的重要因素。然而群落越复杂并不意味着群落越稳定。复杂性增加已经显示会导致不稳定。此外，群落的不同组分（如种丰富度和生物量）也许对干扰有不同反应。具有较低生产力的群落
（如冻原）其恢复力是最低的。相反，较弱的竞争可以使许多的物种共存，从而减少群落的不稳定性。
There are tow components to stability – resilience and
resistance,which describe the community‘s ability to
recover from disturbance and to resist change,Complexity
is thought to be important in determining resilience and
resistance,However,more complex communities are not
necessarily the most stable; increased complexity has been
shown to lead to instability,In addition,different
components of the communities (e.g,species richness and
biomass) may respond differently to disturbance,
Communities with a low productivity (e.g,tundra) to be
the least resilient,In contrast,weak competition permits
coexistence among species and reduces community
instability.
Community
complexity,diversity
and stability
相关主题 资源分配（见 I3） 食物链（见 P3）
营养复杂性与稳定性食物链的长度也许能够影响群落的恢复力。具有不同营养连接水平的许多群落模型，显示复杂性导致恢复力和稳定性下降。然而，这样的研究应该被谨慎地解释，因为真正的群落所具有的特性在零群落模型中并没有被发现。稳定性也依赖于环境状况 ——一个脆弱的（复杂的或多样的）群落也许能够在一个稳定和可预知的环境中持续下去，而在一个多变的和不可预知的环境中，仅仅简单的和生长旺盛的群落才能够生存下去。
Related topics Resource partitioning (I3) Food chains (P3)
Trophic complexity
and stability
Food chain length may influence the resilience of the
community,Models of communities with different levels
of trophic connectance show that complexity reduces
resilience and stability,However,such studies should be
interpreted with caution,as real communities msy possess
important attributes mot found in the communities of null
models,Stability also depends on environmental
conditions – a fragile (complex or diverse) community
may persist in a stable and predictable environment,while
in a variable and unpredictable environment only simple
and robust communities will survive.
Q2 岛屿群落与移殖要 点物种 -面积关系 岛屿上（或一个地区中）物种数目会随着岛屿面积的增加而增加，最初增加十分迅速，当物种接近该生境所能承受的最大数量时，增加将逐渐停止。物种数目的对数与面积对数的坐标图显示的是一个线性关系。
对于海洋岛屿和生境岛屿来说，这些双对数坐标图直线的斜率，大多在 0.24~0.34之间。对于连续生境内的亚区域，斜率接近 0.1。随着面积增加，物种多样性增加的效果在岛屿上要比连续生境内明显。
The number of species on an island (or in any area) will
increase with the size of the island,The increase is initially
rapid,tailing off at the maximum number of species for a given
habitat,A plot of log species number against log area gives a
linear relationship,For oceanic islands or islands of habitat,the
slopes of these log-log plots mostly fall within the range 0.24-
0.34,For subareas within continuous habitat,the slope is
around 0.1,The effect of increasing species diversity with
increasing area is more pronounced on islands than within
continuous habitat.
Key Notes
The species-area
relationship
Q2 ISLAND COMMUNITIES
AND COLOMOZATION
岛屿生物地理学麦克阿瑟和威尔逊的岛屿生物地理学理论指出，岛屿上物种的数目是由新移殖来的物种和以前存在物种的灭绝之间的动态平衡决定的。当移殖种的数目增加时，
到达岛屿的移殖来的物种的数目会随着时间的推移而减少。相反，当物种之间的竞争变得强烈时，灭绝的速率就会增加。当灭绝和移殖的速率达到相等时，物种的数目就处于平衡稳定状态。模型研究也证明了物种的数目会随着岛屿面积的增加而增加，和随着距移殖者源距离的缩短而增加。对模型研究有利的证据，
是由对除去动物的岛屿上物种的再移殖的观察，和对最近隔离的岛屿物种的丧失结果所提供的。当与邻近大陆对照的时候，灭绝和移殖过程说明了岛屿植物区系和动物区系的衰亡。
MacArthur and Wilson‘s theory of island biogeography states
that the number of species found on an island is determined
by a dynamic equilibrium between the immigration of new
colonizing species and the extinction of previously established
ones,As the number of colonizing species increases,the
number of immigrants arriving on the island decreases over
time,In contrast,as competition among species becomes more
intense,the extinction rate increases,The point at which
extinction and colonization rates are equal gives the number
of species at equilibrium,the model also accounts for the
increase in species number with increasing island size and
decreasing distance from a source of colonists,Extinction and
colonization account for the depauperate flora and fauna of
islands when compared to the adjacent mainland.
Island
biogeography
岛屿和异质种群异质种群理论已经替代了岛屿生物地理学来解释片断化生境的“岛屿”种群行为。异质种群含有许多种群，
这些种群之间通过迁入和迁出而交换个体。与岛屿不同，生境斑块（ patch）是在景观镶嵌板块（ landscape
mosaic）之中的，景观板块能够影响斑块的性质和它所含的物种种类。
相关主题 种内竞争（见 I2） 保育对策（见 V2）
稀有物种、生境损失和灭绝（见 V1）
Related topics Intraspecific competition (I2) Conservation strategies (V2)
Rare species,habitat loss and
extinction (V1)
Islands and
metapopulations
Metapopulation theory has superseded island
biogeography in explaining the behavior of populations in
islands‘ of fragmented habitat,A metapopulation consists
of a number of populations that exchange individuals
through immigration and emigration,Unlike islands,
habitat patches are embedded in a landscape mosaic that
can influence the quality of the patch and the species it
will contain.
Q3 群落格局、竞争和捕食要 点群落集合 集合规则（ assembly rule）的概念企图解释自然群落是如何不同于来自物种库中的物种而随机装配出来的群落。群落集合也许能被生境类型、物种移殖和定居，
或者种内的相互关系，像捕食、寄生和竞争所影响。
集合规则研究群落组成中的格局，将那些由“零
(null)‖群落模型所产生的格局与真实的群落格局相比较。
The concept of assembly rules attempts to explain how
natural communities vary from random assemblages derived
from the range of available species (the species pool),
Community assembly may be influenced by habitat type,
species colonization and establishment,and /or by
interspecific relationships such as predation,parasitism and
competition,Assembly rule studies investigate patterns in
community make- up,comparing real community patterns
with those generated by?null‘ community models.
Key Notes
Community
assembly
Q3 COMMUNITY PATTERNS,
COMPETITION AND PREDATION
竞 争 竞争可能是形成群落结构的一个重要力量，但是在调查的时候，它又不一定是重要的。过去竞争的痕迹在群落中可以留下很深的烙印（像生态位的分化）。竞争的一些研究已经表明，生态学上相似物种组成的同资源种团当中，仅仅只有一个成员在群落中能够生存，
这就意味着其他相似物种被竞争排斥了。岛屿上超飘流的鸟类物种的分布也支持了该理论，即竞争导致了群落的结构化。
Competition can be an important force shaping community
structure but is not necessarily significant at the time of
investigation,The ghost of competition past can leave a
strong imprint on a community (e.g,as niche differentiation),
Some studies of competition have shown that only one
member of a guild of ecologically similar species tends to be
present in the community,suggestive of competitive
exclusion of other similar species,The distribution of
supertramp bird species on islands also supports the theory
that communities are structured by competition.
Competition
食肉动物 选择捕食和转换猎物能够使稀有物种免遭捕杀。这种行为能够导致许多相对稀少的物种在同一个群落中共存。
食草动物 食草动物对植物群落有两个作用：（ i）它们选择摄食影响群落的物种多度。（ ii）啃食抑制了竞争物种的生长，因此加速和维持了低竞争物种的多样性。当啃食强度很强时，物种多样性降低，物种会局部灭绝。
Grazing animals have two effects on plant communities,(i)
their selective feeding affects species abundance in the
community,and (ii) grazing suppresses the growth of
competitive species thus enhancing and maintaining the
diversity of less competitive species,When grazing intensity
is very high,diversity can be reduced as species are forced
to local extinction.
Grazers
Selective predation and prey switching can leave rarer
species unpredated,This behavior can lead to the
coexistence of a large number of relatively rare species in
the same community.
Carnivores
相关主题 种内竞争（见 I2） 演替（见 R1）
资源分配（见 I3） 群落对干扰的反映（见 R2）
关键物种 关键（ keystone）物种在群落中有一个重要的和不成比例的作用。关键种可能是顶端的捕食者，像北方的海獭；然而这个词可以运用在任何一个物种上，只要这个物种被移去时会对群落结构造成重大影响。
Related topics Intraspecific competition (I2) Community responses to
Resource partitioning (I3) disturbance (R2)
Succession (R1)
Keystone species A keystone species has a significant and disproprtionate effect on the community,Keystone species can be top
predators such as the northern sea otter; however,the term
can be usefully applied to any species whose removal
would have a significant effect on community structure.
R1 演 替要 点演替 ——经典模型生态演替是指在一个自然群落中，物种的组成连续地、
单方向地、有顺序地变化。这一顺序被称为是一个演替序列，最后达到的阶段称为顶级。早期的演替阶段，
具有先锋物种、低生物量和低营养水平的特征。随着演替的进行，群落的复杂性增加，通常在演替的中期阶段，复杂性达到最大。一个中期的演替群落具有高生物量、高有机营养水平和高的物种多样性。
Ecological succession is defined as a continuous,
unidirectional,sequential change in the species
composition of a natural community,This sequence of
community is termed a sere,and culminates in the climax
community,Early successional stages are characterized by
pioneer species,low biomass and often low nutrient levels,
Community complexity increases as succession progresses,
often peaking in the mid-successional stage,A mid-
successional community is characterized by high biomass,
high levels of organic nutrients and high species diversity.
Key Notes
Succession –the
classical model
R1 SUCCESSION
自发演替 自发演替的动力来自于生物与它们环境之间的相互作用。原生演替（ primary succession）发生在新近形成的基质上，如冰川沉积物。先锋物种的营养物的增减和腐殖质的积累为新物种移殖做好了准备。次生演替是由于干扰引起的，如洪水、火灾和人类活动。在这两种自然发生的演替中先锋物种的移殖很快，在较强竞争力的物种入侵之前充分利用空间。耐阴物种（ shade-
tolerant species）成为阴影处的主宰者，它们是一些较慢的移殖者。
Autogenic succession is self-driven,resulting from the
interaction between organisms and their environment,
Primary succession occurs on a newly formed substrate
such as glacial till,Nutrient enhancement and litter
accumulation by pioneer species allow new species to
colonize,Secondary succession follows disturbance,for
example by flooding,fire or human activity,In both types
of autogenic succession pioneer species colonize quickly
making opportunistic use of resources before the invasion
of more competitive species,Shading leads to dominance
by shade-tolerant species which tend to be slow colonizers.
Autogenic
succession
退行性演替 退行性演替是涉及到移殖和死亡有机体后来腐烂分解的自发演替的一种类型。当有机物质降解耗尽了一些资源和制造了其他可以利用的资源的时候，不同的物种就交替地出现和消失。这个过程导致了腐殖质的生产，并且对土壤形成过程起着重要作用。
异发演替 异发演替是由外界环境因素引起的，像长期的气候变化（如冰河时期）和环境在短时间内的变化（如沉积物的增加）。群落结构随时间的变化从沉积物芯样的花粉分析来看是十分明显的。演替依赖于物种对环境条件（如盐分）的忍耐性。
Degradative succession is a type of augogenic succession
involving colonization and subsequent decomposition of dead
organic matter,Different species invade and disappear in turn,
as the degradation of the organic matter uses up some resources
and makes others available,This process leads to the
production of humus and is important in soil formation.
Degradative
succession
Allogenic succession results from external environmental
factors,such as long term climatic change (e.g,ice ages) or
environmental change over a short time (e.g,sediment
accretion),Changes in community structure over time are
apparent from pollen analysis of sediment cores,Successional
progress depends on species tolerance to environmental
conditions such as salinity.
Allogenic
succession
演替过程 演替受三个过程的强烈影响：
（ i）促进：正在发展的群落所产生的非生物环境变化，
允许其他物种的入侵。
（ ii）抑制：一个阶段的物种抵制后来演替的物种的入侵，以至于入侵仅仅在干扰或死亡后才有可能。
（ iii）耐受：后期演替的物种的入侵，因为它仍能够忍受较低的资源水平和排斥早期演替的物种。能忍受低资源水平的强竞争的物种，将取代好的机会迁移者而统治顶极群。
Succession is strongly influenced by three processes.
(i) Facilitation,changes in the abiotic environment that are
imposed by the developing community and allow other
species to invade.
(ii) Inhibition,species of one stage resist invasion by later
successional species such that invasion is only possible
following disturbance or death.
(iii) Tolerance,late successional species invade because
they are able to tolerate lower resource levels and can
outcompete early successional species,Highly
competitive species,which are tolerant of low resource
levels will replace opportunistic good colonizers and
come to dominate the climax community.
Successional
processes
波动和顶级群落作为一个地理区域，没有一个单一的顶极群落，但是都有一个连续的顶极类型系列沿着环境梯度变化着。
顶极群落是不稳定的，但是它处于一个连续涨落之中。
当演替在早期阶段被阻止的时候，朝向顶极的单向演替并不总是发生的。总之，生物量和物种多样性随着演替的进行而增加，但常常在演替中期阶段达到最大，
而不是在顶极群落时。
相关主题 群落对干扰的反应（见 R2）
Related topics Community responses to disturbance (R2)
Fluctuations and the
climax community
There is no single climax community for a geographic
area,but a continuum of climax types varying along
environmental gradients,Climax communities are not
stable,but are in a state of continual flux,Unidirectional
succession to the climax does not always happen as
succession can be arrested at an earlier stage,In general,
biomass and species diversity increase with succession but
often peak at an intermediate stage and not at the climax
R2 群落对干扰的反应要 点干 扰 干扰是指林中倒树、食草动物的啃食、潮汐活动、火灾、反常气候变化或人类活动等经常发生的扰乱或干涉，它们迫使物种经历某些选择压力。比如生长在易发生火灾的环境中的植物，在形态和生活史方面有其独特的适应，以保证它们自己和后代在这样的环境中生存下去。
A disturbance is an interruption or interference that occurs
sufficiently often for it to have exerted some selection pressure
on the species experiencing it,Disturbance includes trees
falling in a forest,grazing by herbivores,tidal action,fire,
unusual climatic conditions or human activity,Plants of
environments prone to disturbance such as fire have
morphological and life history adaptations to ensure the
survival of themselves or their offspring.
Key Notes
disturbance
R2 COMMUNITY RESPONSES TO
DISTURBANCE
干扰对物种丰富度的作用干扰可增加群落的物种多样性，因为它能阻止少数竞争力强的物种成为优势，使其他物种有机会入侵。如果某个地方的种群，由于干扰而不断减少，此地的竞争排斥就可能使那些本来相互竞争的物种停止竞争，
而共存在一起。
中度干扰假说 当干扰为新物种创造了可移殖的断层的时候，物种多样性趋向最大。但这种干扰强度和频率均低于物种移殖的速度，因而在更大的群落中不会导致物种数的下降。如果干扰小，群落会被一些顶级物种统治。如果干扰很强并经常发生，就会对物理或土壤环境造成影响，从而完全改变群落。
Disturbance can cause an increase in community species-
richness by preventing dominance by a few competitive
species and allowing opportunistic species to invade,Where
populations are continually reduced by disturbance,
competitive exclusion can be prevented and potentially
competing species may be able to coexist.
Effects of
disturbance on
species richness
Maximum species diversity tends to be achieved when
disturbance creates gaps for new species to colonize,but is
not intense or frequent enough to community,At very low
levels of disturbance the community is dominated by a few
climax species,Very severe of repeated disturbance may
have an impact on the physical or edaphic environment and
alter the community completely,
Effects of
disturbance on
species richness
斑块动态 群落的局部性干扰产生了许多断层，相同的或不同的物种个体就乘机移殖到这些断层上来。由于物种移殖到哪个断层是随机的，因此相互竞争的物种可能不会在同一断层上相遇。这样就会使物种丰富的群落生存下来。在晚期演替群落中，如森林群落，断层经历了一个微型演替（ mini-succession）的过程，因此形成了一个由处于不同演替阶段的各类斑块组成的镶嵌体。
Localized disturbance of a community creates gaps which
can then be colonized by individuals of the same or another
species,Potentially,competing species may not encounter
one another because of the stochastic nature of gap
colonization,allowing species-rich communities to persist,
In a late successional community such as a forest,gaps
undergo a mini-succession resulting in a mosaic of patches
at different stages of succession.
Patch dynamics
建设者控制群落在有些群落中，所有的物种似乎都移殖的不错，彼此在竞争上不分优劣。斑块移殖只是个别现象而已。有些珊瑚礁鱼群落就是如此，由于没有哪一个物种比任何其他物种更喜欢移殖，所以多样性高。在英国的
Chalk草地群落中就存在着相似的情况。
相关主题 演 替（见 R1）
In some communities it seems that all species are equally
good colonizers and are equally matched competitively,
Here patch colonization is a matter of chance alone,This is
the situation in some reef fish communities,Diversity is
high because on one species is more likely to colonize than
any other,A similar situation exists in chalk grassland
communities England.
Founder-
controlled
communities
Related topics Succession (R1)
S1 生态系统格局要 点植被与气候 地球植被被明显地分为许多区域或形式，这些区域或形式在很大程度上反映了气候条件。这种分布是由于植物对温度和水分适应的结果。事实上，第一张气候图和标准的 Koppen气候分类是建立在植被图基础之上的。 Koppen绘制的大的植物分区是我们现在所说的生物群系（ Biome）。生物群系表达的是世界上主要的群落类型的划分。生物群系由动植物种类明显的结合以及具有大致相同生活型（ life form）的植被如杂草或落叶树组成。
The vegetation of the earth is divided into distinct blocks or
formations which broadly reflect climatic conditions,This
pattern arises as a result of the adaptation of plant form to
temperature and water availabilty,The first climate map and
the standard Koppen classification of climate were,in fact,
based on vegetation maps,The great plane formations mapped
by Koppen are what we now call biomes,Biomes represent the
divisions of the major community types of the world,
consisting of distinctive combinations of plant and animal
species and characterized by an approximately uniform life
form of vegetation,such as grass or deciduous trees.
Key Notes
Vegetation and
climate
S1 EOSYSTEM PATTERNS
群落交错区 在局域和地区范围内，当物种个体沿着环境梯度变化的时候，群落也发生了变化。物种、群落和生物群系的边界是不明显的和非突然断开的。而是模糊的和逐渐的。沿着生态交错区（ ecotone），生物群系彼此融合。在这个连续体上植被图勾画出的边界指出了一个生物群系大概从哪结束，另一个从哪开始。
On the local and regional scale communities vary as the
individual species respond to environmental gradients,The
boundaries of individual species,communities and biomes
are not distinct and abrupt,but blurred and gradual,
Superimposes boundaries on this continuum,indicating
approximately where coe biome ends and another begins.
Ecotones
温度和分布 霜冻的危害也许是限制植物分布的最重要的单一因素。
在一些情况下，物种分布的限制很可能与阻止物种生存的致死温度相关的。在物种的分布限制与等温线之间找出密切的对应关系是很普通的事情。朗基耶尔
（ Raunkiaer）的生活型分类就是建立在植物的分生组织对霜冻适应脆弱性的基础之上的。
Damage by frost is probably the single most important
factor limiting plant distribution,In some cases it is
possible to relate to relate the distributional limits of a
species to a lethal temperature which precludes survival,
It is common to find a close correspondence between the
distributional limits of a species and an isotherm,
Raunkiaer‘s classification of life forms is based on the
vulnerability of plant meristems to frost.
Temperature and
distribution
相关主题 适应（见 B1） 群落、结构和稳定（见 Q1）
应付环境变异（见 B2） 草地（见 S2）
太阳辐射与气候（见 C1） 冻原（见 S3）
微气候（见 C2） 森林（见 S4）
温度与物种分布（见 E3）荒漠、半荒漠和灌丛（见 S5）
太阳辐射与植物（见 F1）
Related topics Adaptation (B1) community,The structure and stability (Q1)
Coping with environmental variation (B2) stability (S2)
Solar radiation and climate (C1) Tundra (S3)
Microclimate (C2) Forests (S4)
Temperature and species Deserts,semi-deserts and
distribution (E3) shrubland (S5)
Solar radiation and plants (F1)
S2 草 地要 点基本区域 草地存在于降雨介于荒漠和森林之间的区域。依据温度的不同，草地有两种主要的类型：热带草地（萨旺纳 Savannah）和温带草地（欧亚草原 Steppe、北美草原
Prairie和南美草原 Pampas）。草地在北美洲、北欧和非洲占据着广大的区域，与气候不适合荒漠或森林发育的荒漠或森林混生在一起。
Grasslands occur where rainfall is intermediate between that of
deserts and forests,There are two major types of grassland
depending on the temperature,tropical grassland (savannah),
and temperate grassland (steppe,prairie and pampas),
Grasslands occupy vast areas in North America,northern
Europe and Africa,blending into desert or forest where the
climate is unsuitable.
Key Notes
Primary regions
S2 GRASSLANDS
气候与土壤 热带草地在湿季可以得到 1200mm（ 60英寸）以上的雨水，但是在持续的旱季却一滴雨都没有。较低的土壤湿度可以阻止营养物循环和减少营养物的获得性。温带草地每年得到的降水在 250和 600mm（ 10~30英寸）
之间。气候是大陆性气候，即夏季炎热而冬季寒冷。
草地土壤具有大量的有机物质并且是非常肥沃的，它们非常适宜如玉米和小麦等农作物的耕作。
Tropical grasslands may receive up to 1200 mm (60
inches) of rain in the wet season,but none during the
prolonged dry season,Low soil moisture impedes nutrient
cycling and reduces nutrient availability,Temperate
grasslands have between 250 and 600 mm (10-30 inches)
of rainfall per annum,The climate is continental with hot
summers and cold winters,Grassland soils receive a large
amount of organic matter and are very rich,making them
well suited to the growing of arable crops such as corn
and wheat.
Climate and soils
主要植被 草地具有很高的初级生产力和相对低的生物量。管理的草地被用来作为农田和牧场。草地群落是以禾草类为优势，但是常常也包含一些树木，如金合欢树，它是非洲萨旺纳群落的特点。温带草地包括阔叶的多年生植物，这些多年生植物要么在较早的季节开花，要么在禾死亡之后开化。
草地动物 非洲萨旺纳草原养活了大量的食草和食叶动物种群。
这些食草动物反过来又养活了数目庞大的哺乳类食肉动物。植被结构的单一性、树木的稀少和短的生长季节限制了鸟类和两栖类的多样性。
Grasslands have a high primary productivity and
relatively low biomass,Managed grasslands are used for
crops and for rangeland,Grassland communities are
dominated by grass species but frequently include trees,
such as the acacia which is characteristic of the African
savannah,Temperate grasslands include broad-leaved
perennials which either flower early in the season or after
grasses have died down.
Major vegetation
The African savannah supports large populations of
grazing and browsing animals,These herbivores in turn
support large numbers of mammalian carnivores,The
uniformity of the vegetation structure,the absence of
trees and the short growing season limit the diversity of
birds and amphibians.
Grassland
animals
环境关系 强烈的放牧管理的草地能够导致草地群落的破坏、土壤侵蚀和沙漠化。最初的温带草地动物区系，由于猎杀和草地转变为农耕地及牧场，已经几乎灭绝了。大的食草动物、洞穴动物和捕食者现在在自然状况下要么灭绝了，要么就是十分稀少。为了满足兽群的迁移性行为，热带草地中的国家公园必须很大，或者必须有适合生境的走廊相连接。
相关主题 土壤形成特性和分类（见 G3） 生态系统格局（见 S1）
保育对策（见 V2） 初级和次级生产力（见 P2）
Intensive grazing of managed grasslands can lead to the
destruction of grassland communities,soil erosion and
desertification,The original temperate grassland fauna has
been almost extinguished by hunting and the conversion of
grasslands to arable cultivation and rangelands,Large
herbivores,burrowing animals and predators are now
either extinct in the wild or rare,In order to accommodate
the migratory behavior of herds,national parks in tropical
grasslands must be very large,or be connected by
corridors of suitable habitat.
Environmental
concerns
Related topics Soil formation,properties and Ecosystem patterns (S1)
classification (G3) Conservation strategies (V2)
Primary and secondary production (P2)
S3 冻 原要 点基本区域 北极冻原 （ arctic tundra）在北部的北冰洋和极地冰盖与南部的针叶树森林之间，形成了一个环绕极地的带。
但是，较小的，生态学上相似的这种区域在高山的林线以上也有分布，称之为 高山冻原 （ alpine tundra）
The arctic tundra forms a circumpolar band between the
Arctic Ocean and the polar ice caps to the north and the
coniferous forests to the south,Smaller,but ecologically
similar regions found above the tree line on high mountains
are called alpine tundra.
Key Notes
Primary regions
S3 TUNDRA
气候与土壤 在一年的大多数时间里，温度都是在植物生长所需要的温度以下。降水量较低（通常每年少于 250mm）而且主要以降雪的形式出现。在地面以下的一定深度，
存在着永远不化的永冻层（ permafrost）。较低的生产力和有限的微生物活动导致了土层很薄。
主要植被 冻原具有很低的生产力，但是却具有很高的物种丰富性。植被是由很矮的垫状和形成小丘状的植物组成。
夏季日照很长并伴有较高的温度，这样使植物的初级生产力，在一年的这一时期要比冬季高一个数量级。
The temperature falls below that required for plant growth
of most of the year,Precipitation is low (usually less than
250 mm) and occurs mainly as snow,Below a certain depth
the ground remains permanently frozen forming permafrost,
The low productivity and limited microbial activity result
in thin soils.
Climate and soils
Tundra has a low productivity,but a high species richness,
The vegetation consists of low-growing mat-and
hummock-forming plants,The long day length during the
summer,combined with higher temperatures,allows
primary productivity at this time of the year to be an order
of magnitude higher than in the winter.
Major vegetation
冻原动物 冻原严酷的季节性意味着一些动物仅在夏季才迁移到这里。永久的居住者如驯鹿是迁移性的，为了寻找充足的食物，它们在广阔的区域内迁移。
环境关系 冻原植被和土壤从干扰中恢复过来是很缓慢的。由于在冻原带发现石油，植被已经丧失以及土壤发生了侵蚀。冻原的发展控制和保护是一个世界性的问题。
相关主题 初级和次级生产力（见 P2） 生态系统格局（见 S1）
保育对策（见 V2）
The extreme seasonality of the tundra means that some
animals are only present as summer migrants,Permanent
residents such as reindeer are migratory,ranging over vast
areas in order to find enough food.
Tundra animals
Tundra vegetation and soils are very slow to recover from
disturbance,Since the discovery of oil in the tundra,
vegetation has been lost and sosils eroded,The control of
development and protection of the tundra is an international
problem.
Environmental
concerns
Related topics Primary and secondary production (P2) Ecosystem patterns (S1)
Conservation strategies (V2)
S4 森 林要 点基本区域 森林类型依赖于降雨和温度（纬度和高度）。北方针叶森林是寒冷气候与高海拔的象征。温带森林出现在低纬度地区，那里有充足的降雨，向赤道为热带雨林所替代。
The arctic tundra forms a circumpolar band between the
Arctic Ocean and the polar ice caps to the north and the
coniferous forests to the south,Smaller,but ecologically
similar regions found above the tree line on high mountains
are called alpine tundra.
Key Notes
Primary regions
S4 FORESTS
气候与土壤 北方针叶林具有漫长而寒冷的冬季同时冬季降水很少，
夏季降雨很多。土壤是灰壤。温带森林的气候也是季节性的，具有很高的降雨量。土壤发育很好并且肥沃。
有热带，森林气候是非季节性的并且温暖，降频繁的大雨。土壤是淋溶的、酸性的和养分贫瘠的。
Boreal forests have long,cold winters with light
precipitation in the winter and more rain in the summer,
The soils are podzols,The climate of temperate forests is
also seasonal,with higher rainfall,Soils are well
developed and rich,In the tropics,the forest climate is
non seasonal and warm with frequent heavy rainfall,Soils
are leached,acidified and nutrient poor.
Climate and soils
主要植被 森林具有达到很高的净初级生产力和高生物量的趋势。
北方森林以针叶树种为优势种，这些种类适应于降低的蒸腾蒸散量以及在结冰时组织不损坏。温带森林主要由阔叶落叶种类组成，植被复杂的层次结构导致很高的初级生产力。热带雨林的高生物多样性来自于它们漫长的年龄和复杂的物理环境。
Forests tend to have a high net primary productivity and
also a high biomass,Boreal forests are dominated by
coniferous tree species which are adapted to minimize
evapo-transpiration and tissue damage from freezing,
Temperate forests consist mainly of broad-leaved,
deciduous species and the complex layered structure of
the vegetation leads to high primary production,The
high biodiversity of tropical rainforests results from
their great age and complex physical environment.
Major vegetation
森林动物 温带和北方森林养活了食草的哺乳动物（如鹿）和像狼一样的捕食种类。森林对鸟类来说是重要的栖息地，
而且在温带森林里，小型的哺乳动物居住在稠密的森林下层。森林生态系统也含有范围很广的专食性和泛食性的食草昆虫。热带雨林支持了巨大的动物多样性，
尤其是昆虫、两栖类、爬行类、鸟类和小型的哺乳动物。许多物种是居住在树上的，以吃果实和 /或种子为生。
Temperate and boreal forests support herbivorous mammals
(e.g.deer),and predatory species such as wolves,Forests are
important habitats for birds and,in temperate forests,small
mammals which inhabit the dense understorey,Forest
ecosystems also contain a wide range of specialist and
generalist insect herbivores,Tropical rain forests support
tremendous animal diversity,particularly of insects,
amphibians,reptiles,birds and small mammals,Many species
are tree dwelling,feeding on fruit and /or fruit and/or seeds.
Forest animals
环境关系 砍伐热带雨林可以导致生物多样性的丧失，土壤发生水土流失。森林生物多样性代表的是全球有价值的资源，因为许多植物种类具有独一无二的对人类有益的化学特性。砍伐森林能引发全球变暖和发生洪水灾害。
许多温带和北方森林正在遭受酸雨的危害。
相关主题 生态系统格局（ S1） 温室气体和全球变暖（ W2）
生物资源和基因库（ V3）
The clearing of tropical rain forests results in biodiversity
loss,depletes the soil and may lead to erosion,Forest
biodiversity represents a valuable global resource as many
plant species have unique chemical properties that can be
beneficial to mankind,Forest clearance contributes to
global warming,and may cause flooding,Many temperate
and boreal forests are suffering damage from acid rain.
Environmental
concerns
Related topics Ecosystem patterns (S1) Greenhouse gases and global
Biological resources and warming (W2)
gene banks (V3)
S5 荒漠、半荒漠和灌丛要 点基本区域 热荒漠分布在北纬 30° 和南纬 30 ° 之间。半荒漠生态系统出现在并不太干旱但水分又是有限的区域。温带灌丛出现在地中海海岸周围，那里是以马基群落，即常绿高灌丛林（ maquis）闻名，在南加利福尼亚是以北美夏旱灌木群落，即小槲树林（ chaparral）而闻名。
Hot deserts are found around latitudes 30° N and 30° S,
Semi-desert ecosystems occur in less arid regions,but where
water remains limiting,Temperate shrubland is found around
the shores of the Mediterranean Sea,where it is known as
maquis,and in southern California where it is called chaparral.
Key Notes
Primary regions
S5 DESERTS,SEMI-DESERTS AND
SHRUBL AND
气候与土壤 荒漠每年的降雨量少于 50mm，白天炎热夜晚凉爽。土壤养分贫瘠，土层薄而且容易流失。当降雨的时候，
雨水能很快的渗入地下或沿着季节性河流流走。北美夏旱灌木群落和马基群落是季节性的而且降雨少又具有很长的旱季。由于缺乏湿度和经常的火灾，分解和土壤发育都受到抑制。
Deserts have less than 50 mm of annual rainfall,hot days
and cold nights,Soils are nutrient poor,thin and freely
drained,When rainfall does occur it usually penetrates
the soil very quickly or runs over the surface in
temporary streams,Chaparral and maquis are seasonal
and have low rainfall with a prolionged dry season,
Decomposition and soil development is impeded by lack
of moisture and frequent fires.
Climate and soils
植 被热荒漠的植被包括多刺的灌木、一年生的短命植物、
地下的球茎、鳞茎和肉质植物如仙人掌。所有这些植物都具有在长期干旱的情况下生存的适应性。冷荒漠具有稠密的灌木植被和丰富的微植物区系。北美夏旱灌木群落具有小的、厚的能够抵御干旱的叶片，并且该群落被有规律的火灾所维持。
Hot desert vegetation includes thorny shrubs,ephemeral
annuals,underground corms and bulbs,and succulents,
such as cacti,All have adaptations allowing them to
survive long periods of drought,Cool deserts have denser
shrub vegetation and abundant microflora,Chaparral
contains species with small,thick,drought-resistant leaves
and the community is maintained by regular fire.
Vegetation
荒漠动物 爬行动物和昆虫是容易在荒漠条件下生存的。然而，
一些哺乳动物包括啮齿类动物和骆驼都已经进化出了适应干旱条件的行为。半荒漠和灌丛是爬行动物、小哺乳动物和鸟类的重要栖息地。
环境关系 荒漠生产力受降雨量的限制。那里土壤是合适的，灌溉能够使荒漠转换成有生产力的农业田地。然而，荒漠灌溉能够导致盐渍化，并且为农作物而改变河道可以对其他地区的生态学产生破坏性的影响。
相关主题 生态系统格局（ S1）
Reptiles and insects are most able to survive desert
conditions,However,some mammals,including rodents
and camels,have evolved means of coping with the arid
conditions,Semi-deserts and shrublands are important
habitat for reptiles,small mammals and birds.
Desert animals
Related topics Ecosystem patterns (S1)
Desert productivity limited by rainfall,Where soils are
suitable,irrigation can convert deserts to productive
agricultural land,However,desert irrigation can lead to
salinization and diverting rivers to crops can have a
devastating impact on the ecology of other regions.
Environmental
S6 盐水生物群系要 点基本盐水区域 盐水生物群系包括开阔的海洋、大陆架、潮间带和珊瑚礁、盐水沼泽、潮泥滩和红树林。海洋覆盖了 70%的地球表面。物理因素即潮汐、环流、温度、压力（深处的）和光强度决定着生物盐水群落的组成。
The saltwater biomes are open oceans,continental shelves,
the intertidal zone and coral reefs,salt marsh,mudflats and
mangroves,Oceans cover 70% of the world‘s surface,
Physical factors,namely tides,currents,temperature,
pressure (depth) and light intensity,determine the makeup
of biological salt water communities.
Key Notes
Primary
saltwater regions
S6 SALTWATER BIOMES
开阔海洋开阔的海洋是面积最广阔的生物群系，但是它却养分贫瘠，因此，它的生产力是低的。表面的有光带，即光可以透过的地方，含有浮游植物和浮游动物。在有光带以下，生存的是食肉和食碎屑的动物，它们依靠来自上面群落的物质为生。光的水平和生产力随深度增加而降低。除了生活在热水带出口区域的繁盛的化学自养细菌群落外，海底或海底的动物区系是稀少的。
The open ocean is the most extensive biome in area,but it
tends to be nutrient poor and hence4 unproductive,The
surface photic zone,where light can penetrate,contains
phytoplankton and zooplankton,Below the photic zone
carnivorous and detritivorous animals occur,feeding on
material with depth,Bottom or benthic fauna is sparse
except in regions of hydrothermal vents where communities
based on chemotrophic bacteria thrive.
Open oceans
大 陆 架 大陆架支持了最具生产力的海洋生态系统，如海藻林和渔业。多样化的珊瑚礁群落出现在温暖和非常浅的水域。珊瑚是群体动物，这些动物产生了结构复杂的钙质骨架，藻类、无脊椎动物和食草与食肉的鱼类生活在它上面。
潮 间 带 潮间岩石海岸被藻类所主宰。随暴露和离海洋的距离而发生藻类带和动物群落。沙滩提供了一个不稳定的、
研磨的（ abrasive）和养分贫瘠的基质，这种基质被滤食性的穴居动物所居住，而它们自己又是涉禽鸟类的食物。
Continental shelves support some of the most productive of
marine ecosystems,such as kelp forests and fisheries,
Diverse coral reef communities occur in warm and very
shallow water,Coral are colonial animals which produce
structurally complex calcareous skeletons on which live algae,
invertebrates and herbivorous and carnivorous fishes.
Continental
shelves
Intertidal rocky shores are dominated by algae,Zonation of
algal and animal communities with exposure and distance
from the sea occurs,Sandy beaches provide an unstable,
abrasive and nutrient-poor substrate inhabited by filter-feeding
burrowing animals which are themselves food for wading
birds.
The intertidal
zone
盐沼、淤泥滩和红树林盐沼出现在防护区域，具有防护海浪的作用，它主要是由耐盐的高等植物组成。淤泥滩和江河入海口处的淤泥是很细的基质，富含有机物质和低的含氧量。它们很高的无脊椎动物密度养活了鱼类和鸟类种群。红树林在热带区域取代了盐水沼泽，并且支持了丰富的动物区系。
Salt marsh occurs in sheltered areas protected from wave
action and is dominated by salt-tolerant higher plants,
Mudflats and estuarine silts are fine substrates rich in
organic matter and low in oxygen,Their high invertebrate
density supports fish and bird populations,Mangrove
forests replace salt marsh in tropical regions and support a
rich fauna.
Salt marsh,
mudflats and
mangroves
环境关系 开阔海洋被用作倾倒许多污染物的场所，这些污染物包括油、污水、碳氢化合物和金属。一些污染物在食物链中被放大而污染鱼类资源。潮间的娱乐和商业活动已经导致生境的破坏和污染。挖泥、污水污染和过度捕鱼已经引起珊瑚礁的退化。
相关主题 渔业与捕鲸业（见 T2）
Related topics Fishing and whaling (T2)
The open ocean is used as a dumping ground for numerous
pollutants,including oil,sewage,hydrocarbons and metals,
Some become magnified in the food web and can
contaminate fish stocks,Recreational and commercial
development of intertidal regions has led to habitat
destruction and pollution,Dredging,sewage pollution and
over-fishing have degraded coral reefs.
Environmental
concerns
S7 淡水生物群系要 点主要的淡水和湿地区域淡水生物群系包括湖泊、河流、酸性沼泽、草本沼泽和木本沼泽。这些系统靠从附近排水区沥滤的水和营养物生存。
Freshwater biomes include lakes,rivers,bogs,marshes
and swamps,These systems are fed by water and
nutrients leaching from the surrounding catchment area.
Key Notes
Primary
freshwater and
wetland regions
S7 FRESHWATER BIOMES
溪流和河流溪流和河流的物理特征沿水体长度而有变化。它们靠近源头的窄小湍急，变成河口附近的宽广平缓。植物和动物的多样性和生产量在中部地区通常是最高的，
因为那儿的水流速度和河床底质允许大型植物的生长。
湖泊和池塘 湖泊的水很少流动或者不流动，使得水体可垂直分层，
包括表层光照充足而温暖的水和下层黑暗而寒冷的水，
湖泊可以是营养充足的（富营养型），或者是营养匮乏的（贫营养型）。
The physical characteristics of streams and rivers alter
along their length; they change from being small and
turbulent close to their source to wider and slower at
their mouth,Plant and animal diversity and production
tends to be highest in the middle regions where flow
rates and substrate allow the growth of macrophytes,
Streams and
rivers
Lakes have very little or no current,allowing the water
body to acquire vertical stratification with illuminated,
warm water at the surface and dark,cold water below,
Lakes can be nutrient rich (eutrophic) or nutrient poor
(oligotrophic).
Lakes and ponds
环境关系 开凿运河、商业开发和污染造成了许多河流下游水生生物和河岸植被的减少，湿地被用于农业，变成了农田和牧场。富营养化由生物或非生物的污染而造成，
结果导致植物多样性的减少和藻类的大量生长。这个问题在小湖泊、小池塘以及半封闭系统如英国的
Norfolk 宽阔河段中尤其显著。
相关主题 空气、水和土壤污染物（ W1）
Related topics Air,water and soil pollutants (S7)
Canalization,commercial development and pollution have
resulted in a loss of aquatic biota and bankside vegetation
in the lower reaches of many rivers,Wetlands have been
lost to agriculture for grain production and grazing,
Eutrophication can occur through organic and inorganic
pollution,resulting in a loss of plant diversity and algal
blooms,This is a particular problem in small lakes and
ponds and in semiclosed systems such as the Norfolk
Broads.
Environmental
concerns
T1 收获理论要 点收获目标 为了使种群开发获得最大回报，管理应以使对象种群可长期持续获得最大产量为目标。
To maximize the returns gained by exploiting a population,
management should aim to harvest the maximum yield that
the maximum yield that the population can produce
sustainably over the long term.
Key Notes
The goals of
harvesting
T1 HARVESTING THEORY
最大持续产量 长期收获最大产量的一种方法是最大持续产量即 MSY
法。随着种群密度在很低的基础上开始增加，出生率超过死亡率，种群的净补充量增加。当种群密度达到最大环境容纳量时，死亡率上升，出生率下降。因此最大净补充量发生在中等密度、种群中存在许多繁殖个体、而种内竞争又相对较弱的情况下。这一最大净补充量即为人们可长期从种群中收获的最大量 ——
MSY。
One approach to deduce the maximum long-term yield is
known as the maximum sustainable yield,or MSY approach,
As a population increases in density from very low numbers,
the birth rate outstrips the death rate,so the net
recruitment(births-deaths) into the population rises,As the
population density approaches the maximum the
environment can support,the death rate increases and the
birth rate falls,The maximum net recruitment therefore
occurs at an intermediate density,when intraspecific
competition is relatively low yet there are many reproductive
individuals in the population,This maximum net recruitment
is the maximum number that can be harvested from the
population sustainably – the MSY.
Maximum
sustainable yield
配额限制 在一定时期，可通过控制配额（收获对象生物量或个体数量），限制收获。配额控制允许收获者在每一季节或每年收走一定数量的猎物。配额限制通常应用于海洋渔业来获得 MSY，但成功例不多。这表明配额限制实际上很冒险，有可能导致过捕，甚至种群灭绝。
Harvesting may be limited by controlling the quota (the
biomass or number of individuals culled ) in a given period,
Quota controls thus allow the harvesters to remove a fixed
number of the prey species every season or year,Quota limi-
tataion is commonly applied in marine fisheries to achieve a
MSY with limited success,The theory demonstrates that
quota-limitation is intrinsically risky and may cause
overexploitation and even extinction of the harvested
populations.
Quota limitation
努力限制 配额限制潜在的危险或通过导入努力限制来缓和。努力限制具有明显的优点。因为当猎物种群数量减少时，
人们往往会通过更加努力来获限正在减少中的数量。
环境波动 利用种群增长模型预测被收获种群可获潜能的效果会受到环境波动的严重影响。因为环境波动会影响种群的出生率或死亡率。
The ability of models of population growth to predict the
harvesting potential of a population is esverely compromised
by environmental variation which may affect recruitment or
mortality.
Environmental
fluctuation
The risk inherent in quota-limitation can be alleviated by
adopting an approach of limiting effort,This has a clear
advantage- as a prey species becomes rarer,more effort will
be required to seek out and catch the diminishing numbers.
Effort limitation
相关主题 种群和种群结构（ H1） 密度和密度制约（ H3）
出生率、死亡率和种群增长（ H2） 种群动态 ——波动、周期和混沌（ H4）
动态库模型 简单的模型不考虑种群的年龄结构，这使其预测能力有限，因为死亡率与繁殖力都是与年龄相关的。收获个体通常都是种群中体大、年高的个休，具有最高的繁殖潜能。精确地考虑到不同年龄群出生率、生长和死亡率的动态库模型对对象种群的预测效果更好。举例来说，考虑到不同年龄群的动态库模型意味着可理论上检测海洋渔业中使用不同大小网具的影响效果。
Simple models do not consider the age structure of
populations,which limits their predictive power,as the
mortality rates and reproductive output of individuals is age-
specific,Usually,the individuals harvested are the larger and
older members of the population,which have the highest
reproductive potential,Dynamic pool models explicitly
consider the recruitment,growth and mortality of different
age classes,allowing a better model of the population to be
derived,This approach means that,for example,the impact
of varying mesh size in a marine fishery can be tested
theoretically.
Dynamic pool
models
Related topics Populations and population Density and density
structure (H1) dependence (H3)
Natality,mortality and Population dynamics –fluctuations,
growth (H2) cycles and chaos (H4)
T2 渔业和捕鲸业要 点渔 业 海洋一直为我们人类提供丰富的食物资源。现在全球渔获量约 1亿吨，其中一小部分并不直接被人类消费，
而是用做动物饲料。
大洋生产力 与陆地系统相比，大洋是生产力很低的生境。大陆架生产力较高，但全球单位公顷渔获量很低，部分是因为大洋区极低的生产力，部分是由于渔获物处于食物链高营养级，其生产效率很低。
The seas have historically provided a valuable food source to
human populations,The current global fish catch is about
100 million tons,although a substantial minority of this is
not used for direct human consumption,but as an animal
feed source,
Key Notes
Fisheries
T2 FISHING AND WHALING
The open oceans are very unproductive habitats compared to
terrestrial systems,Productivity is higher on the continental
shelves,but the overall global fish catch represents a very
low yield per hectare,This is partly because of the very low
productivity of most of the ocean area,and partly because
the harvest consists on animals high up the food chain,
which have low production efficiencies.
Ocean
productivity
公共灾难 公共灾难假说指的是公共享有的资源（如没有任何政府管辖的公海）容易由于个体私利而导致利用过度。
这种行为不可能进行最大长期持续产量的管理，并使种群遭到破坏和毁灭。
过 捕 由于过捕，渔业资源正处于全球性下降，几乎所有地区年渔获量都在减少。过去两个世纪人们一直在大量捕鲸，现已导致过捕，鲸数量大幅度下降。
The hypothesis of ‘ the commons‘ suggests that a commonly
shared resource (such as open oceans outside the control of
national governments ) will tend go be overexploited by
selfish individuals,Such behavior makes impossible any
management to maximize long term yields,and will lead to
population crashes and extinctions,
The’ tragedy of
the commons’
Globally,fish stocks are in decline due to overexploitation,
with the annual catch declining in almost all regions,Whales
have been fished intensively for the past two centuries,
which has resulted in overexploitation and a dramatic
decline in numbers.
Over-exploitation
附带收获问题 多数渔业技术导致非对象种或个体的偶然性收获 ——
附带收获问题。附带收获的非对象种或个体被扔回大海，死亡。由于该问题造成种群的非控制性破坏，因此是主要环境问题之一。附带收获个体包括对象种中太小的个体、海豚、鲨鱼、鸟类（如褐眉信天翁）和海龟。
Most fishing techniques result in the incidental capture,?by-
catch‘,of nontarget species or individuals,which are thrown
back,dead,into the sea,This is a major environmental
problem as it represents the uncontrolled destruction of
populations,By-catch can consist of individuals of the target
species which are too small,dolphins,sharks,birds (such as
the brown-browed albatross) and turtles.
The by-catch
problem
相关主题 捕食的性质（ J1）
污 染 来自人类活动的污染的污染影响到水体食物链，有一些影响到渔捞对象种。主要污染物是石油、有毒化合物和有机废物。油泄漏使地区海洋生物遭到破坏，通常表现为渔获量长期减少。有毒化合物通常通过食物链危害人类消费者，如 60年代发生在日本水俣（ min-
imata）的氯化甲基汞毒害事件。含有氮磷的污水和农肥会导致水华和富营养化。富养化环境会引起当地水域鱼类和无脊椎动物死亡以及珊瑚的毁灭。
Pollutants from human activities affect the aquatic food
chain,and some of these have impacts on harvested species,
Major pollutants are oil,toxic chemicals and organic waste,
Oil spills cause local devastation to marine life,but generally
appear to result in limited long-term effects on the harvested
stocks of fish,Toxic chemicals can be passed down the food
chain and pose a risk to human consumers,as occurred in the
methylmercuric chloride poisoning incident in Minimata,
Japan it the 1960s,Sewage and agricultural fertilizers
containing nitrogen and phosphate may lead to algal blooms
and invertebrate deaths as well as the destruction of corals.
Pollution
Related topics The nature of predation (J1)
U1 有害生物问题及其防治对策要 点有害生物是什么？
有害生物和人类竞争食物或空间、传播病原体、以人为食，或用不同方法威胁人类健康、舒适或安宁。野草可能包括在这个定义内。有害生物最重要特征之一，
是它们通常被它们的天敌调节到高的水平。有害生物是经常能逃避它们天敌的物种，可能是由于它们迁入世界新的地区。
Pests compete with humans for food of shelter,transmit
pathogens,feed on humans or otherwise threaten human
health,comfort or welfare,Weeds may be included in this
definition,One of the most important characteristics of pests
is the high degree to which they are normally regulated by
their natural possibly due to their importation to new regions
of the world,
Key Notes
What is a pest?
U1 THE PEST PROBLEM AND
CONTROL STRATEGIES
有害生物防治目标尽管在有些情况下，有害生物防治的目标是根除有害生物种，然而通常有害生物的防治目的总是降低有害生物种群到一个水平上，在这个水平上进一步降低是无利可图的。这被称为有害生物的经济损害水平
（ EIL），如果考虑到社会的和环境的舒适利益，或许它被称为美学损害水平（ AIL）。就疾病而言，根除全部有害生物能够被认为是有理的，这是基于救活一个人远超过任何经济的价值。在实践有害生物的防治中，
EIL不像防治活动阈值（ CAT）那样重要，在经济活动阈值这个有害生物密度上，其作用应该被理解是阻止即将来临的有害生物的爆发。
Although in some instances the aim of pest control is to
eradicate the pest species,generally the aim of pest control is
to reduce the pest population to a level at which on further
reductions are profitable,This is known as the economic
injury level (EIL) for the pest,or if social and amenity
benefits are included,the aesthetic injury level (AIL),In the
case of disease,total eradication can be justified on the basis
that the saving of one single life far exceeds any economic
costs,In practical pest control,the EIL is not as important as
the control action threshold (CAT) – the pest density at
which action should be taken in order to prevent an
impending pest outbreak.
The aim of pest
control
相关主题 捕食的性质（ J1） 杀虫剂和问题（ U2）
捕食行为和猎物反应（ J2） 生物防治和害虫综合治理（ U3）
有害生物防治类型限制有害生物损伤粮食作物的方法已被采用数千年，
特别是用于栽培防治（例如改变播种日期、或避免在同一地区重复种植相同的作物）。生物防治（利用天敌 ——捕食者与寄生物）也具有悠久的历史。本世纪以来，化学防治变成主要的途径，尽管存在着严重的毒性和其他一些问题。抗有害生物的作物品种的培育是另一类有价值的对策。
Approaches to limit pest damage to food crops have been
adopted for thousands of years,particularly using cultural
control (e.g.altering the sowing date or avoiding repeatedly
replanting the same crop in the same place),Biological
control (the use of natural enemies – predators and parasites)
has also had a long history,This century,chemical control
became a key approach,although there are serious toxicity
and other problems,The development of pest – resistant crop
varieties is another valuable strategy.
Types of pest
control
Related topics The nature of predation (J1) Pesticides and problems (U2)
Predator behavior and prey Biological control and integrated
response (J2) pest management (U3)
U2 杀虫剂和问题要 点化学杀虫剂和除莠剂无机化合物是除莠剂的惯用试剂，但由于具有持久性和非特异性的问题，如像硼酸盐和含砷制剂的化合物是极少应用的。化学杀虫剂一般用于处理特殊地点上的特殊害虫。可是问题出现了，因为这些化合物对其他动物是有毒的，并且很多化学物持续存在于环境中。
Inorganic compounds were traditional herbicides,but due to
problems with persistence and nonspecificity,compounds
such as borates and arsenicals are rarely used,Chemical
pesticides are generally used to treat a particular insect pest
at a particular location,However,problems arise because
these chemicals are toxic to other animals,and because
many chemicals persist in the environment.
Key Notes
Chemical
insecticides and
herbicides
U2 PESTICIDES AND PROBLEMS
化学毒性 大多数化学杀虫剂对一系列有机体有毒，超出了目标有害生物物种。杀虫剂是特别有问题的，很多的杀虫剂影响了广泛的脊椎动物和无脊椎动物。对非目标物种的冲击，能够引起生态的、经济的和人类健康问题。
除莠约的作用经常是相当无特异性的，有些也可能毒害哺乳动物。
Most chemical pesticides are toxic to a range of organisms,
beyond the target pest species,Insecticides are particularly
problematic,many affecting a wide range of vertebrates and
invertebrates,The impact on nontarget species can cause
ecological,economic and human health problems,
Herbicides are often fairly unspecific in their action,and
some may also be mammalian toxins.
Chemical toxicity
生物放大作用 进一步的问题出现了，特别是在使用氯化烃中，这是由于它们对生物放大作用的灵敏性。由于它们的毒素不能代谢，或者不能被破坏，它们就累积在个体的体内。这就导致在更高营养级上的有机体中，农药的浓度增加。这些效应威胁了自然的捕食者种群，并可能对人类食物链形成危险（尤其是当鱼受到影响时）。
A further problem arises,particularly,in the use of
chlorinated hydrocarbons,because of their susceptibility to
biomagnification,Because these toxins cannot be
metabolized or destroyed,they accumulate in the body of an
individual,This results in an increasing concentration of
insecticide in organisms at the higher trophic levels,These
effects threaten natural predator predator populations and
may pose a risk to the human food chain (especially if fish
are affected).
Biomagnification
目标害虫再起和次生病虫害爆发杀虫剂，除了高特异性的之外，可能毁掉大部分天敌种群，导致有害生物的数量在开始的下降之后迅速地增加 ——这是“害虫再起”。当天敌被消灭时，通常受天敌牵制的许多潜在的有害生物种，其数量可能增加，变成次发性病虫害。
Insecticides,unless highly specific,may decimate natural
enemy populations,leading to a rapid increase in pest
numbers after an initial decline –this is?pest resurgence‘
When natural enemies are destroyed,a number of potential
pest species normally kept in check by their natural enemies
may increase in number and become secondary pests.
Target pest
resurgence and
secondary pest
outbreaks
相关主题 捕食的性质（ J1） 生物防治和害虫综合治理（ U3）
寄生的性质（ K1）有害生物问题及其防治对策（ U1）
抗性进化 有害生物对杀虫剂产生了进化抗生，使农业生产受到严重威胁。杀虫剂的抗性提供了一些当前作用中的最好进化例证。暴露到杀虫剂中的一个巨大种群内，只有很少的基因型可能有特异的抗性，并具有极大的进化优势。
Evolved resistance to pesticides represents a serious threat to
agricultural production,Pesticide resistance provides some
of the best examples of evolution in action,Within a large
population exposed to pesticide,a few genotypes may be
unusually resistant and will possess a huge evolutionary
advantage.
Evolution of
resistance
Related topics The nature of predation (J1) Biological control and integrated
The nature of parasitism (K1) pest management (U3)
The pest problem and control
strategies (U1)
U3 生物防治和害虫综合治理要 点生物防治 生物防治是利用一个种害虫的天敌去防治那种害虫。
生物防治有四种类型。从另一个地理区域引入一种天敌，经常被称为经典生物防治或输入。预防接种是相似的，但需要防治剂的定期释放，因为它不能持续贯穿在一年中。扩大牵涉到土产天敌的重复释放，以便增补存活的种群。爆发是天敌大量的释放，同时伴随着捕杀那些有害生物。
Biological control is the utilization of a pest‘s natural
enemies in order to control that pest,There are four types of
pest control,The introduction of a natural enemy from
another geographical area is often termed classical biological
control or importation,Inoculation is similar but requires the
periodic release of a control agent where it cannot persist
throughout the year,Augmentation involves the repeated
release of an indigenous natural enemy in order to
supplement an existing population,Inundation is the release
of large numbers of a natural enemy,with et\ht aim of killing
those pests present at the time.
Key Notes
Biological control
U3 BIOLOGICAL CONTROL AND
INTEGRATED PEST
MAGAGEMENT
微生物杀虫剂 到目前为止，昆虫是生物防治有害生物和野草两者的主要力量，出现在生物防治的全部 4个类型中。近来，
在害虫的防治中，把更多的注意力集中在应用昆虫的病原体上，主要地作为微生物的杀虫剂。苏云金芽孢杆菌（ Bacillus thuringiensis）是防治害虫的惟一微生物因子，它已经成为世界性的商品。病毒，特别是杆状病毒，也已被分离出来，引起昆虫和螨得病。真菌大约有 100属对昆虫是致病性的，并是潜在的防治剂。
Up until recently,insects have been the main agents of
biological control against both pests and weeds,in all rour
types of biological control,Recently,increasing attention in
the control of insect pests has focused on the use of insect
pathogens,largely as microbial insecticides.The bacterium,
Bacillus thuringiensis,is the only microbial pest control
agent that has been commercialized worldwide,Viruses,in
particular the baculovirus,have also been isolated which
cause disease in insects and mites,There aer around 100
genera of fungi which are pathogenic to insects and are
potential control agents.
Microbial
insecticides
基因防治和抗性自绝控制是利用有害生物自身增加它自己的死亡率。
这通常牵涉到释放不育性的雄性，导致出生率降低。
基因操纵的另一种类型是选择植物品种对抗害虫（也有除草剂）。已筛选出有抗性的品种，近来植物的复杂基因操作已变成可能。发展和利用这样的转基因植物，对潜在的环境和安全是有利的。然而，还存在着公众的感性认识和与技术相关的合法问题，而且进化的抗性问题如同化学杀虫剂的问题一样大。
Autocidal control uses the pest itself to increase its own rate
of mortality,This usually involves the release of sterile
males,leading to a decrease in birth rate,Another type of
genetic manipulation is to select plant varieties resistant to
pests (and also herbicides),Resistant varieties have been
selected and recently sophisticated genetic manipulations of
plants have become possible,There are potential
environmental and safety benefits from the development and
use of problems associated with technique,and the problems
of evolved resistance are as great as with chemical pesticides.
Genetic control
and resistance
相关主题 捕食的性质（ J1） 有害生物问题及其防治对策（ U1）
寄生的动态（ K2） 杀虫剂和问题（ U2）
害虫综合治理 害虫综合治理（ IPM）与其说是特殊的、限定的对策，
结合了物理的、栽培的、生物的和化学的防治，和利用抗性品种，不如说是有害生物的治理哲学。确定最适对策需要大量时间和精力的投入，但是有长期的环境和经济效益。
Integrated pest Management (IPM) is a philosophy of pest
management rather than a specific,defined strategy,
combining physical,cultural,biological and chemical
control and the use of resistant varieties,A considerable
investment of time and effort is required to determine the
optimum strategy,but there are long term environmental and
economic benefits.
Integrated pest
management
Related topics The nature of predation (J1) The pest problem and control
The dynamics of parasitism (K2) strategies (U1)
Pesticides and problems (U2)
V1 稀有物种、生境损失和灭绝要 点稀 有 种 稀有性的类型取决于该种的三个属性 (Rabionwitz,1981)：
（ i）地理分布区的大小（大或小）；（ ii）栖息地特异性（宽或窄）；（ iii）地方种群大小（高或低）。对于任何物种，这些特征中有一个或几个的属性低，证明其某些稀有性。窄的栖息地要求、低的种群密度和地方性都是稀有性的各个方面。许多种是由于其生态学而成为稀有的，另一些种则由于人类活动的结果。扩散能力弱或有固着行为的物种，很可能由于人类因素而成为稀有的。
The type of rarity depends on three attributes of the species
in question (Rabinowitz,1981)(i)size of geographical range
(large v,small);(ii)habitat specificity (wide v.narrow);
(iii)local population size (high v,low).Any species for which
one or more of these attributes is low population density and
endemism are all different facets of rarity,Many species are
rare by virtue of their ecology while others are rare as a
result of human activities.Species with poor dispersal ability
of sedentary behavior are likely to become rare as a result of
anthropogenic factors.
Key Notes
Rare species
V1 RARE SPECIES,HABITAT LOSS
AND EXTINCTION
稀有种的遗传多样性数量下降得很低的种会遭受到遗传多样性丧失和杂交衰退。为了保证遗传多样性得以维持，要求种长期生存，需要有最小可存活种群（ MVP）。人们接受的避免杂交衰退的最好估计值是 250~500个体的 MVP。精确的确定 MVP要求有详细和长期的研究，优先保护栖息地的考虑，常常使得对于遗传多样性的关心有所失色。
A species which has declined to low numbers will suffer
from a loss of genetic diversity and inbreeding depression,A
minimum viable population (MVP) is required for the long-
term survival of a species to ensure genetic variability is
maintained,An MVP of 250-500 individuals is accepted as
the best estimate for inbreeding avoidance,Detailed and
lengthy study is required for the accurate determination of
MVP and frequently the protection of habitat is the
conservation priority,overshadowing concern over genetic
diversity.
Genetic diversity
in rare species
生境损失和片断化数目众多的生境，如湿地、草地和森林，面积剧烈地减少，或者被改变，或者受破坏，通常是为了农业。
生境的退化导致物种的减少或损失。生境片断化减少了生境面积，使留下斑块之间的距离扩大。通常生境质量较差的这种小斑块，遭受边缘效应，支持与连续生境不相同的种。物种损失的原因是生境面积的大量损失和鸟屿化过程的加剧。新近分割出的斑块含有的种数，开始可能比长期保持的地区还要多一些，但物种将会从斑块中丧失，这个过程叫做松弛 (relaxation)。
Numerous habitats,such as wetlands,grasslands and forests,
have been either drastically reduced in area,modified or
destroyed,usually for agriculture,Habitat degradation
results in the decline or loss of species,Habitat
fragmentation reduces the habitat area and increases the
distance between remaining patches,These smaller patches
of usually poorer quality habitat suffer from edge effects and
support different species to continuous habitats,Species are
lost because of the overall loss of habitat area,and as a result
of increasing insularization,Recently isolated patches may
initially contain more species than the area can sustain over
the long term and species will be lost from the patch – a
process known as relaxation.
Habitat loss and
fragmentation
灭 绝 灭绝是一个自然过程，但灭绝的步伐和方式由于人类活动而加速。过去的灭绝聚集在地质时间中（如二叠纪和更新世出现的重大灭绝）。灭绝的人为原因包括捕猎、生境破坏和人工引种。 IUCN分类的面临灭绝大风险的物种叫做“濒危物种（ endangered）”。小种群更易于由于直接或间接的日常种群波动的结果而成为濒危物种。种群数量变动和遗传因素相互作用导致灭绝。种群灭绝的概率可以通过种群生存力分析
（ population viability analysis,PVA）进行预测。
相关主题 遗传变异（见 O1） 保育对策（见 V2）
岛屿群落与移植（见 Q2）
Extinction is a natural process,although its pace and
incidence have been increased through human activity,Past
extinctions are clustered in geological time (e.g.significant
extinction occurred in the permian and Permian and
Pleistocene),The anthropogenic causes of extinction include
hunting,habitat destruction and artificial species
introductions,The IUCN categorizes species facing
considerable risk of becoming extinct as? endangered‘,
Small populations are more likely to become endangered as
a direct or indirect result of normal population fluctuations,
Demographic and genetic factors interact to cause extinction,
The chance of a population becoming extinct can be
predicted by Population Viability Analysis(PVA),
Extinction
Related topics Genetic variation (O1) Conservation strategies (V2)
Island communities and colonization (Q2)
V2 保育对策要 点生物多样性 生物多样性是包括全部层次的有机体变异性的术语，
从属于同一种的遗传变体，到物种多样性和生态系统的变异。生物多样性的保育包括遗传变异的保护、物种和种群多样性的保护、以及生态系统的生命支持特性，例如气候与排水效应的保护。
Biodiversity is a term encompassing the variety of organisms
at all levels,from genetic variants belonging to the same
species,to species diversity and including the variety of
ecosystems,The conservation of biodiversity includes the
preservation of genetic variation,the diversity of species and
populations and also the life support properties of
ecosystems,such as climatic and drainage effects.
Key Notes
Biodiversity
V2 CONSERVATION STRATEGIES
地球最高级会议，里约热内卢（ 1992）
1992年里约热内卢召开的地球最高级会议通过了国际生物多样性公约，它促进了生物多样性的重要地位。
152个国家在公约上签字，委托他们通过法律为保育生物多样性和保证从生物多样性取得的利益的公正性，
采取各种方法和手段。 21世纪议程（ Agenda 21）是鼓励 21世纪社会、经济和环境持续发展的一个蓝皮书。
The importance of biodiversity has been promoted by the
International Convention on Biological Diversity,part of the
Earth Summit held in Rio de Janeiro in 1992,The
Convention was signed by 152 nations committing them by
law to adopt ways and means for the conservation of
biodiversity and to ensure equity of benefits from biological
diversity,In addition,Agenda 21 is a blueprint to encourage
sustainable development socially,economically and
environmentally in the 21st century.
The Earth
Summit,Rio de
Janeiro (1992)
保育对策 保育对策应该包括一系列不同尺度和详细程度的层次，
全球的、国家的、地区的和地方的，以适应于各种明显不同政治尺度的保育目标。国际级对策对于保育全球受威胁生态系统是基本的，由世界自然保护联盟领头。濒危野生动植物种国际贸易公约（ CITES）为防止非法进口和出口进行工作。南极公约和近来的南极公约环境保护协议（ 1992）是一个例子，说明如何逾越政治边界。
国家级的保育对象由政府组织安排和通过立法执行，例如保护地区的建立。
Conservation strategies exist at a range of different levels of
detail and scale,global,national,regional and local,to
accommodate the markedly different political scales at
which conservation objectives are directed,International
strategies are essential for the conservation of globally
threatened ecosystems and are led by the World
Conservation Union,The Convention on the International
Trade in Endangered Species (CITES) works to prevent
illegal imports and exports,The Antarctic Treaty and the
more recent Protocol on Environmental Protection to the
Antarctic Treaty (1992) are examples of how political
boundaries can be transgressed,
At the national level,conservation objectives are set by
governmental organizations and implemented through
legislation,e.g,for the establishment of protected areas,
Strategies for
conservation
自然保护区设计一般说来，保护区越大，区内物种数就越多。但是，
许多小保护区可能比一个同样面积大保护区有更多的物种。一个大保护区还是几个小保护区之争论叫做
,SLOSS‖之争。最好的协调可能是一组彼此相连的小保护区，它允许区间有扩散和遗传交换。保护值最大的另一种方法是在保护区周围设置一个同样生境的缓冲区。保育可存活种群所需要的最小面积可以用计算机模型进行估计。
In general,the larger the reserve,the greater the number of
species in it,However,many small areas may contain more
species in total than one reserve of the same area,The debate
over the relative merits of a single large or several small
reserves is known as the?SLOSS‘ argument,The best
compromise may be a network of small,linked reserves
which allows dispersal and genetic interchange to takd place
between areas,Another way of maximizing the conservation
value of a reserve is to surround the reserve with a buffer
zone of the same habitat,The minimum area required to
retain a viable population can be estimated by computer
modeling.
The design of
nature reserves
环境评估 环境评估是在没有进行某地整个生物多样性的详细和耗时调查以前，确定该地保护价值的一种方法。选择地点的根据可能是具有少数引人注目的和敏感的物种，
它们可以作为更大的群落的指示种。
相关主题 岛屿群落与移植（见 Q2）
稀有种、生境丧失和灭绝（见 V1）
Environmental assessment is the means by which the
conservation value of a site may be assessed without detailed
and time-consuming surveys of its entire biodiversity,Sites
may be selected on the basis of a small number of conspicu-
ous and sensitive species which are taken as indicative of the
larger community,
Environmental
assessment
Related topics Island communities and Rare species,habitat loss and
colonization (Q2) extinction (V2)
V3 生物资源和基因库要 点生物资源 自然种群和生态系统作为生物资源已经被利用好多世纪。过度利用导致了资源的下降，甚至种群灭绝和生境破坏。然而，持续利用不破坏资源，并保证生境和种群为将来的利用而保护着。狩猎种群为捕猎而维持着，森林为木材而维持着。由于药物工业对植物产品的依赖，所以植物多样性具有现实的、潜在的商业价值。农作物及其相关植物物种的生物多样性是很有价值的，因为这种多样性提供了植物繁育的机会。
Natural populations and ecosystems have been exploited for
centuries as biological resources,Overexploitation leads to
the decline of the resource and even population extinction
and habitat destruction,Sustainable use,however,does not
damage the resource and ensures that habitats and
populations are conserved for future use,Game populations
are maintained for bunting,forests are maintained for timber,
General plant biodiversity has an actual of potential
commercial value because of the reliance of the
pharmaceutical industry on botanical products,Biodiversity
in crop plant species and their relatives is valuable because
of the plant breeding opportunities such diversity offers.
Key Notes
Biological resources
V3 BIOLOGICAL RESOURCES AND
GENE BANKS
生物资源价值的估计生物资源的经济价值可以通过估计它们提供的总利益而得。资源的总经济价值是其利用价值和非利用价值之和。利用价值囊括了有用产品的价值，例如木材。
非利用价值包括生存价值和给未来世代的利益。生物多样性的利益常常超越国家界限，例如热带森林的碳储存，但是保护生物多样性的花费通常由一个国家所承担。这意味着，生物多样性的价值在实际上是低估了，而有利于其他地方利用的生物多样性，其损失等于是把直接的和目前的利益给予了土地拥有者。
It is possible to ascribe an economic value to biological
resources by considering the totality of the benefits they
provide,The total economic value of a resource is the sum of
its use value and nonuse value,Use values encompass the
value of useful products such as timber,Nonuse values
include the existence value and benefit to future generations,
The benefits of biodiversity (e.g.of carbon storage by
tropical forests) are often spread across national boundaries,
but the costs of conserving biodiversity are usually borne by
one nation,This means that in practice the value of
biodiversity is underestimated and biodiversity is lost in
favor of other land use which delivers direct and immediate
benefits to the land owner,
Valuing biological
resources
生态旅游 生态旅游者为体验国家的生物多样性或国家公园而付了钱。生态旅游是从生物多样性获得经济利益的一种手段，并能有助于偿还保护的费用。生态旅游的缺点是“先导作用”，收入从局部地方的“漏出”和旅游的过度扩展。
基 因 库 当物种及其 DNA不可能就地保护时，就必须在博物馆、
植物标本馆或动物园中易地保护。以动物园、植物园的活生物和种子的形式收藏的物质，与收藏的 DNA合在一起，称为基因库。植物种和作物品种最易储存于种子库。粮食作物的原来的野生种及其品系，对于在未来发展新的作物品种是具有极其重要的价值的。
Ecotoruists pay to exeerience the biodiversity of a country or
national park,Ecotourism is a means of gaining economic
benefit from biodiversity and can help to meet the cost of
conservation,The disadvantages of ecotourism are
spearheading‘,the?leakage‘ of income away from the local
area and overexpansion of tourism.
Ecotourism
Where in situ conservation is not possible,species or their
DNA must be conserved by ex situ methods in museums,
herbaria or zoos if they are to be preserved at all,These
collections of living material in the form of zoo animals,
botanical gardens and seeds,together with DNA collections
have been termed gene banks,Plant species and crop
varieties can be most easily stored in seed banks,The
original wild strains of food crops could be very valuable in
the future in seed banks,The original wild strains of food
crops could be very valuable in the future development of
new crop varieties.
Gene banks
动物园 ——
人工繁育人工繁育计划的目的是在笼养条件下保护受威胁物种，
其最终目的是再引入到野外。为了完全地利用已有的基因库以尽量增加遗产变异，把全世界动物园养着的物种个体，作为单个种群来管理。理想的说，笼养的数量应该达到最小可存活种群，性比应维持 1,1，与不同品系的进行杂交，避免与本地的相交。释放到野外的成效取决于生境质量、面积和保护免受人类干扰等因素。对释放的动物可能要教会它们怎样有效的取食和逃避捕食者。人工繁育动物的再引入充满了困难，
高费用，人们倾向于把它作为就地方法已经失败以后的最后手段。
相关主题 生态学中的性（见 N2） 保育对策（见 V2）
稀有种、生境丧失和灭绝（见 V1）
Captive breeding programmes aim to conserve threatened
species in captivity with the ultimate aim of reintroduction
into the wild,In order to make full use of the available gene
pool to maximize genetic variation,individuals of a species
held in zoos around the world are managed as a single
population,Ideally,captive numbers should be built up to the
minimum viable population,the sex ratio should be
maintained at 1:1 and breeding among distinct races and
with domestic varieties should be avoided.
Successful release into the wild depends on factors such as
habitat quality,area and protection from human interference,
Released animals may have to be taught how to forage
effectively and avoid predators,The reintroduction of
captive-bred animals is fraught with difficulties,is expensive
and tends to be used as a last resort after in situ methods
have failed.
Zoos-captive
breeding
Related topics Sex in ecology (N2) Conservation strategies (V2)
Rare species,habitat loss and extinction (V1)
W1 空气、水和土壤污染物要 点空气污染 空气污染是由人类活动引起的天然与合成的有害物质向大气中的排放。污染物可直接进入大气（初级污染物），或在太阳辐射的影响下于大气中产生（次级污染物）。已表明会给环境和健康带来威胁的主要空气污染物包括氧化氮类、二氧化硫、臭氧和固体颗粒。
空气污染也能改变气候以及土壤、湖泊和河流的化学性质。
Air pollution is the transfer of harmful amounts of natural
and synthetic materials into the atmosphere as a consequence
of human activity,Pollutants can be added to the air directly
(primary pollutants),or they can be created in the air
(secondary pollutants) under the influence of solar radiation,
The major air pollutants,which have documented
environmental and health risks,include nitrogen oxides,
sulfur dioxide,ozone,and particulates,Air pollution can also
alter climates and the chemistry of soil,lakes and rivers.
Key Notes
Air pollution
W1 AIR,WATER AND SOIL
POLLRTANTS
酸 雨 欧洲和北美的北温带地区的水体已经遭受到酸雨带来的酸化。酸雨是化石燃烧的结果。化石燃料的燃烧会产生氧化硫类物质（ SOx）和一氧化氮（ NO），它们能分别和大气中的水分结合而形成硫酸（ H2SO4）和硝酸（ HNO3）。这种现象称为“酸降”更恰当，因为酸也会以雪、雨和雾的形式从空气中沉降下来。酸雨降低土壤和湖泊的 pH，同时酸化也能导致树木的死亡，
并使得有毒金属（如铝和汞）从土壤和沉积物中释放出来。
Water bodies in northern temperate regions of Europe and
North America have suffered form acidification due to?acid
rain is a result of fossil fuel burning,which produces sulfur
oxides (SOx) and nitric oxide (NO) which may combine with
atmospheric water to form sulfuric acid (H2SO4) and nitric
acid (HCO3),respectively,The term?acid deposition‘ is
more accurate as acid may also be deposited from the air in
the form of snow,sleet and fog,Acid rain reduces the pH of
soil and lakes,while acidification can also cause the death of
trees and allow toxic metals (e.g,aluminium and mercury) to
be leached from soils and sediments.
Acid rain
水体污染物 水污染分为四类：（ i）生物试剂，（ ii）溶解的化学物质，（ iii）不溶的化学物质和（ iv）热。水生态富营养化是无机营养物过剩造成的。水中的有机物质被微生物分解，降低了溶氧水平。溶氧水平可以由“生化需氧量”（ biochemical oxygen demand,BOD）来定量。
有机水体污染物中非常重要的一类是多氯联苯族化合物 PCBs，这是一组稳定的含氯化合物，对脊椎动物有剧毒。
Water pollution can be divided into one of four categories,(i)
biological agents,(ii) dissolved chemicals,(iii) nondissolved
chemicals,and (iv) heat,The eutrophication of aquatic
ecosystems occurs due to an excess of inorganic nutrients,
Organic matter in the water is broken down by
microorganisms that deplete the oxygen levels,which may
be quantified by the?biochemical oxygen demand‘ (BOD),A
particularly important class of organic water pollutants is the
family of polychlorinated biphenyls (PCBs),a group of
stable chlorinated compounds,that are highly toxic to
vertebrates.
Water pollutants
土壤污染 在导致土壤污染问题的一系列化学物质中，卤素（主要是溶剂和杀虫剂）构成了最大的一类。这些化学物质是人工制造的。污染土壤的最复杂的一类化合物包括多聚物，如尼龙、塑料和橡胶。生物除污是利用微生物净化污染土壤的一项技术。
相关主题 水的特性（ D1） 温室气体和全球变暖（ W2）
土壤形成、特性和分类（ G3） 臭氧（ W3）
A range of chemical cause soil pollution problems,of which
halogens (primarily solvents and pesticides) constitute the
largest group,These chemicals are manufactured,The most
complex group of compounds which are found polluting
soils include polymers such as nylon,plastics and rubber,
Bioremediation is a technique of utilizing microorganisms
for the decontamination of polluted soils.
Soil pollution
Related topics The properties of water (D1) Greenhouse gases and global
Soil formation,properties and warming (W2)
classification (G3) Ozone depletion (W3)
W2 温室气体和全球变暖要 点大气中二氧化碳的浓度二氧化碳（ carbon dioxide）是大气、海洋和生物区系中碳循环的主要载体。存在于岩石圈的化石燃料（煤、
石油和天然气）直到最近几个世纪才被挖掘出来。大气中二氧化碳的浓度从 1750年的 280ppm上升到 1990年约 350ppm，而且仍在增长。增长的主要原因是化石燃料的燃烧。虽然对于未来二氧化碳的释放量和大气中二氧化碳的估计浓度尚有不同，但是到 2050年，二氧化碳浓度很可能上升到平均大约为 550ppm。
Carbon dioxide (CO2) is the main vehicle of carbon flux
between atmosphere,oceans and biota,Fossil fuels (coal,oil
and natural gas) present in the lithosphere lay dormant until
recent centuries,The concentration of CO2 in the
atmosphere has increased from about 280 parts per million
(ppm) in 1750 to about 350 ppm in 1990 and is still rising,
with the main reason for the emissions,and the
concentration to be expected in the atmosphere vary,but is
appears likely that the concentration will rise to a mean of
about 550 ppm by the year 2050.
Key Notes
Carbon dioxide
concentrations in
the atmosphere
W2 GREENHOUSE GASES AND
GLOBAL WARMING
温室效应 ―温室效应”（ greenhouse effect）是这样一种理论，它假设二氧化碳和甲烷这样的普通人为污染物造成的污染会导致全球气温的上升。在过去的一个世纪中，二氧化碳浓度升高，而全球气温也上升了 0.4~0.7℃ 。这个事实支持了上述理论。因为大气中的温室气体（包括水蒸气、二氧化碳和其他人为污染物）能够吸收热量，所以围绕地球的大气层防止了地球热量的全部丧失。如果将大气中的二氧化碳浓度在已有水平上翻倍，
预计气温将上升 3.5 ℃ 左右。
相关主题 太阳辐射与气候（ C1） 臭氧（ W3）
空气、水和土壤污染物（ W1）
The?greenhouse effect‘ is a theory which proposes that
pollution by common anthropgenic (i.e,created by humans)
pollutants such as CO2 and methane may lead to an
increased global temperature,Over the last century,CO2
concentrations have risen and global air temperatures have
increased by 0.4-0.7℃,which supports theory theory,The
atmosphere formed around the Earth insulates the planet
form the full effects of hat loss by trapping heat in the
atmosphere using greenhouse gases,which include water
vapor as well as Co2 and other anthropogenic pollutants,
Doubling of the atmospheric CO2 and other anthropogenic
pollutants,Doubling of the atmospheric CO2 concentration
from its present level is predicted to lead to a further
warming of around 3.5 ℃,
The greenhouse
effect
Related topics Solar radiation and climate (C1) Ozone depletion (W3)
Air,water and soil pollutants (W1)
W3 臭 氧要 点什么是臭氧 臭氧（ O ）是含有 3个氧原子的高活性氧分子，在高空（平流层）有自然形成的一层臭氧。臭氧层对生命非常重要，因为它吸收有巨大危害作用的紫外线辐射。
低空（对流层）的臭氧是有毒的，可由化石燃料释放的光化学烟雾生成。
3
Ozone is a highly reactive oxygen molecule containing three
oxygen atoms,O3,There is a naturally occurring high
altitude (stratospheric) layer of ozone which is important to
life as it absorbs potentially damaging ultraviolet radiation,
Low-altitude (tropospheric) ozone is toxic,and is produced
by photochemical smog resulting from fossil fuel emissions.
Key Notes
What is ozone
W3 OZONE
臭氧屏的重要性在同温层臭氧层即“臭氧屏”（ ozone shield）形成之前，陆地生物的发展受到限制。 DNA大量吸收紫外线，
而紫外光会严重破坏 DNA的复制，导致繁殖的失败和死亡。相对少量的增加紫外辐射会引起复制过程中的突变，从而导致癌细胞的生成。值得注意的是，紫外光对植物的重大损伤会导致初级生产力下降，因而影响整个生态系统。
相关主题 太阳辐射与气候（ C1）空气、水和土壤污染物（ W1）
平流层臭氧缺损含氯氟烃（ CFCs）能降解同温层中的臭氧。当英国南极考察团证实南极臭氧屏出现严重缺损后，这个问题引起了重视。据估计，单个氯原子能破坏 100000个臭氧分子。如果按臭氧损失的现行趋势发展下去，预计到 2050年，臭氧屏将再缺损 10%，这会增加 3亿皮肤癌患者。
Prior to the development of the stratospheric ozone layer
which forms the?ozone shield‘ the evolution of terrestrial
life was inhibited,DNA efficiently absorbs UV light,which
seriously disrupts DNA replication,causing reproductive
failure and death,Relatively small increases in UV radiation
can cause mutations during the replication process that may
result in the production of cancerous cells,A major concern
is the potential damage caused by UV light to plants,Which
could reduce primary productivity,and therefore affect
whole ecosystems.
The importance of
the ozone shield
Chlorofluorocarbons (CFCs) can degrade ozone in the
stratosphere,Attention was focused on the problem when the
British Antarctic Survey demonstrated a strong depletion of
the Antarctic ozone shield,It is estimated that a single
chlorine atom can breakdown 10 000 ozone molecules,If the
trend of ozone loss continues it is predicted that the ozone
shield will be depleted by a further 10% by 2050; this may
lead to an additional 300 million cases of skin cancer.
Stratospheric
ozone depletion
Related topics Solar radiation and climate (C1)
Air,water and soil pollutants (W1)
X1 土壤侵蚀和农业要 点概 述 农业活动对全球的许多生态系统产生了较大影响，同时引起了很多生态问题。农业对生态的影响主要有四个方面：（ i）控制害虫的后果（ U），（ ii）生物多样性的减少（ V3），（ iii）土壤侵蚀和（ iv）营养物、水和能量利用的影响。后两项内容将在这一章进行讨论。
Agricultural practices have a considerable impact on many
ecosystems globally,and give rise to a variety of ecological
problems,Four key areas in which agriculture impacts upon
ecology are (i) the consequences of pest control (Section U),
(ii) reduction in biodiversity (Topic V3),(iii) soil erosion,
and (iv) the effects of nutrient,water and energy use,These
last two subjects are covered in the section.
Key Notes
Overview
X1 SOIL EROSIONG AND
AGRICULTURE
土壤侵蚀的原因土壤侵蚀和拙劣的农事活动造成的土壤肥力下降是严重的世界性问题。大规模去除植被，大面积没有屏障来减慢水运动的土地使用，不适宜的耕作技术，所有这些都造成了土壤侵蚀。
土壤侵蚀的代价大多数现代农业系统建立在短期经济效益的基础上，
由于土壤侵蚀发生非常缓慢，所以短期内似乎没有什么严重后果。土壤侵蚀减少土壤中有机质和养分，降低土壤保水能力，限制扎根深度，从而影响土地的生产力。每年因风蚀和水蚀而损失四百万吨表土，价值约 100亿英镑。过去 50年中，世界 30%的农田因土壤侵蚀而损失，与此同时，由于人口增长，食物需求量也在增加。土壤侵蚀不仅减少土壤生物生产力，而且会带来洪灾。
Soil erosion and the loss of soil fertility as a result of poor
farming practices are serious problems worldwide,The
removal of vegetation cover from soils,the use of large
fields without boundaries to slow water movement and
inappropriate ploughing techniques all fuel soil erosion.
The causes of soil
erosion
Most modern agricultural systems are based on short- term
economic gain and as soil erosion usually occurs very
gradually it may not appear serious over the short term,
Erosion reduces productivity of the land by depleting it of
organic matter and nutrients,Reducing its water-holding
capacity and limiting rooting depth,As much as 4billion tons
of top soil,valued at 10 billion is lost annually from wind
and water erosion,As much as 30% of the world‘s farmland
has been lost to soil erosion in the past 50 years; whilst food
demand increases due to human population growth,Soil
erosion not only reduces the biological productivity of soils,
but also may cause flooding,
The costs of soil
erosion
土壤保护的措施有些方法能用来减少土壤侵蚀。以适当的角度耕作坡田（等高耕作），顺着等高线而不是顺着斜坡开沟。
同时，在土壤裸露地区种植谷物（覆盖作物）能够防止水土侵蚀。免耕农业只需要挖一些窄的裂沟，而不需要对土壤进行耕作。这些办法，配合植物轮作，能够减少土壤损失和保持土壤肥力。但是，这些措施的实施进程很慢。
相关主题 土壤形成、性质和分类（ G3）初级和次级生产力（ P2）
食物链（ P3） 杀虫剂和问题（ U2）
生物资源和基因库（ V3） 养分、水和能量利用（ X2）
A number of methods can be employed to reduce soil
erosion,By ploughing a field at right angles (contour
ploughing) to the slope,furrows follow the contours of the
land rather than the slope,Also,planting crops on areas of
bare field (cover crops) helps to prevent soil erosion,No-till
farming consists of planting a narrow slit trench without
ploughing the soil,These systems,Along with crop rotation,
can all be used to reduce soil loss and maintain fertility,
However,progress has been slow in establishing these
practices.
Soil conservation
practices
Related topics
Soil formation,properties and Pesticides and problems (U2)
classification (G3) Biological resources and gene
Primary and secondary production banks (V3)
Food chains (P3) Nutrient,water and energy use (X2)
X2 养分、水和能量利用要 点增加农业生产力向土壤和作物直接施用无机肥料是增加作物产量的一个简单途径。每公顷平均产量由 1950年年 1.1t上升到
1986年的 2.3t。如果要在 2000年维持 1987年消费水平，
平均粮食产量至少要增加 25%，然而，由施肥而增加的产量正逐年下降,20年前，向美国土地上施肥 1t可使作物增产 15~20t，今天用同样多的肥料只能增产 6~10t。
The direct application of inorganic nutrients to crops or soils
is a simple route to increase crops or soil is a simple route to
increase crop yield,Average yield per hectare has increased
from 1.1 tons in 1950 to 2.3 tons in 1986,To maintain 1987
consumption levels in the year 2000 will require at 25%
increase in average grain yields,However,there are
diminishing returns of fertilizer application; one ton of
fertilizer added to US soil 20 years ago increased the world
grain harvest by 15 to 20 tons today the same amount of
fertilizer would result in only a 6- to 10-ton increase.
Key Notes
Increasing
agricultural
productivity
X2 NUTRIENT,WATER AND
ENERGY USE
肥料对磷循环的影响每年至少有 13× 106t的磷作为肥料撒向农田，此外还有
2× 106t用作家庭洗涤剂。由于农业系统输入大量的磷和氮，世界上许多湖泊为浮游生物的高度生长提供了理想的条件。在这样富营养化的条件下，湖水因浮游植物（尤其是蓝藻类）的高密度生长而变得混浊，大型水生植物生长受到抑制，同时，大量浮游植物的分解会降低溶氧浓度，引起鱼和无脊椎动物的死亡。
农业活动对氮循环的影响砍伐森林，垦荒农田通常导致溪流中氮含量增加，以及进入大气而损失的 N2O量的增加。种植豆科植物，利用根瘤中的固氮菌，有助于氮的固定。氮肥（每年多于 50× 106t）非常重要。因为撒在田里的肥料中有相当一部分经过各种途径进入河流和湖泊，导致富营养化。
More than 13× 106 tons as an additive to domestic
detergents,In many lakes worldwide,the input of large
quantities of phosphorus (and nitrogen) from agricultural
run-off produce ideal conditions for high phytoplankton
activity,In such cases of eutrophication (enrichment),the
lake water becomes turbid because of dense populations of
phytoplankton (often blue-green species) and large water
plants are outcompeted,In addition,decomposition of the
large phytoplankton biomass may lead to low oxygen
concentrations which kill fish and invertebrates.
Effects of fertilizer
use on the
phosphorus cycle
Deforestation,and land clearance in general leads to
substantial increases in nitrogen flux I streamflow and N2O
losses to the atmosphere,The agricultural practice of
planting legume crops,with their root nodules containing
nitrogen-fixing bacteria,contributes further to nitrogen
fixation,The production of nitrogenous fertilizers (more than
50 × 106 tons year-10) is of particular significance because
an appreciable proportion of fertilizer added to land finds its
way into streams and lakes,Leading to eutrophication.
The effects of
agriculture on the
nitrogen cycle
减少养分损失的策略在农业和林业的实践中，生物量的收割和砍伐必然会带走矿质营养。氮的损失引起两个问题，首先，农民为了保证高生产必须向作物添加肥料，其次，从田地渗漏的氮将导致湖泊的富营养化或者进入饮水危害健康。永久性草地上牲畜的养殖（一个人工管理的动植物生物群落）导致氮的低效循环。
荒 漠 化通过土壤灌溉增加粮食产量的方法为农业开辟了新局面。然而，灌溉通常会引起有效水资源的下降。另外，
干旱地区蒸发量大，灌溉会引起土壤盐分的积累即盐渍化（ salinization）。干旱或半干旱土地由于管理不善而不再适于放牧和耕作，称为荒漠化。全球每年荒漠化的土地约有 600万公顷。自然情况下也存在土地荒漠化过程。
The practices of both agriculture and forestry necessarily
involve the removal of biomass and with it,the removal of
minerals,This loss if nitrogen causes two problems,Firstly,
the farmer needs to supplement the crops with manure to
ensure high productivity,Secondly,the nitrogen leached
from land creates to ensure high productivity,Secondly,the
nitrogen leached from land creates problems elsewhere by
contributing to the eutrophication of lakes and finding its
way into drinking water,The management of livestock on
permanent grasslands (a managed animal=plant community)
leads to the inefficient cycling of nitrogen.
Strategies to limit
nutrient loss
One way to increase food production is by irrigation of soil
creating new areas for agriculture,However,irrigation often
leads to a decline in water availability,Another problem is
irrigation of dry areas where evaporation is high results in
soils accumulation salt (salinization),The process of
improper management of arid or semiarid land to the extent
that it is no longer suitable for range or cropland is called
desertification,Actual global losses to desertification are
estimated to be around six million hectares annually,The
process of desertification can also occur naturally.
Desertification
人类消费的肉和谷物热力学第二定律告诉我们，以谷物为食比以吃谷物的动物肉为食能维持与维持更多人的生存，世界上大约有 40%的谷物被牲畜消耗。转化效率是这样的,5kg适于人类食用的植物蛋白，喂食牲畜后，只能变成 1kg适于人类食用的动物蛋白。此外，大量鱼蛋白用来喂养牲口，更是对资源的极低效利用。
传统农业的新作用农业的可持续发展原理在全世界被广泛研究。传统农业的特点是：少量输入（如化肥、灌溉）。营养物的有效积累和循环，作物的多样性和土壤的保护。以豆科植物为基础的轮作是传统农业中常用的增加土壤中氮贮存的方法，轮垦、烧垦是指一块土地被开垦种植产量下降时，由开垦一块新的土地，这种方法是传统农业另一项常用的措施。毫无疑问，这些传统方法的改进有赖于可持续高产技术的大规模推广。
The second law of thermodynamics tells us that for more
people can be supported on grain than on the meat of grain-
eating animals,Approximately 40%of the grain consumed in
the world is consumed by livestock,Efficiencies are such
that 5 kg of vegetable protein suitable for human
consumption,but fed to livestock instead,results in only 1
kg of livestock protein are used to feed animal stock,which
is a very inefficient use of resource.
Meat versus grain
fir human
consumption
Throughout the world the principles of sustainable
agriculture are being studied,Traditional agriculture
practices are characterized by few external inputs (e.g,
chemicals,irrigation),the effective accumulation and cycling
of nutrients,diversity in cropping and protection of the soil,
Legume-based crop rotations are common in traditional
agriculture to build up nitrogen reserves in the soil,Shifting
cultivation,a practice by which an area is cleared and farmed
and then,as yields decrease,a new area is cleared,is another
traditional method of agriculture commonly practiced,
Without question,the adoption of sustainable and higher-
yielding techniques.
A new role for
traditional
agriculture
相关主题 来源与循环（ G1） 植物和消费者（ G2）
组成成员和过程（ P1） 初级和次级生产力（ P2）
食物链（ P3） 土壤侵蚀和农业（ X1）
Related topics Sour and cycles (G1) Food chains (P3)
Plants and consumers (G2) Soil erosion and agriculture (X1)
Components and processes (P1)
Primary and secondary production (P2)