LANDSCAPE ECOLOGY
SREM 3011
LECTURE 3
Dr Brendan Mackey
Department of Geography
The Australian National University
Framework for analysing plant
and animal distributions?
stochastic versus deterministic
processes?
forcing functions/response functions
generic set of environmental forcing
functions?
generic scale(s) of analysis?
in situ versus ex situ observations
Aspects of environmental variables that have been considered in vegetation studies and their
principal effects on plants (modified from Billings 1952)
A,Radiation regime; B,Temperature or energy exchange regime;
C,Nutrient regime; D,Water regime; E,Living regime in time or space
or factors controlling plant responses,(After Scott 1974)
VARIABLES ASPECTS PLANT REGIME
VARIABLES ASPECTS PLANT REGIME
Examining physical environment in terms of
plant response:
what role does variable/attribute play in controlling either:
1,The distribution through space and time
and/or
2,The availability to plants of:
- temperature
- radiation
- water
- nutrients
Primary Environmental Regimes
1,Radiation
2,Thermal
3,Moisture
4,Mineral Nutrient
Two Landscapes
1A Shaded 1B Exposed
Low radiation High radiation
2A Shaded 2B Exposed
1A and 2B experience similar radiation levels
1.
2,
MESO
Delivery of primary
environmental resources
places that look different to humans
may ‘deliver’ the same level of primary
environmental resources
processes controlling resource delivery
vary in their temporal delivery (eg
seasonal and year-to-year variations)
some contributing environmental factors
are temporally stable (eg,topography)
Biotic feedbacks/regulation?
biota plays a critical role at micro- and
nano-scales
but feedbacks occur at all scales,
especially meso- and global-
at larger scales,effects are due to the
longer-term,agglomerative impacts of
the biota (eg,catchments,Earth)
EXTANT BIOLOGICAL
RESPONSE
physiognomic structure
taxonomic composition,
abundance,viability
process rates
DISTURBANCE
REGIMES
intensity
duration
extent
type
BIOLOGICAL
REGIMES
competition
dependencies
genetic variation
PRIMARY ENVIRONMENTAL
REGIMES
thermal
radiation
moisture
mineral nutrient
TEMPORAL
REGIMES
historic biogeography
biological evolution
seasonal changes
ANTHROPOGENIC
REGIMES
land use history
land use impact
extant land cover
infrastructure
To model estimates of PERs requires integration of:
(1) Climatic attribute data
(2) Topographic attribute data
(3) Substrate attribute data
Climate and topography - two of the major influences
on plants and animals
Climate provides inputs to all PERs
- precipitation,evaporation,radiation,temperature
Topography affects climate locally (slope,aspect,
horizon-shading) and regionally (orographic rain,
temperature lapse rates)
- affects water flow and soil water availability and
nutrient availability
Two forms of source data:
1,‘Point’ data
- usually an irregular (scattered) network of survey
sites at which observations/measurements are made
- soil,vegetation,topography,wildlife,climate
Problem:
How to spatially extend data from point to area?
2,Spatially distributed data
- values recorded on a regular grid
- satellite imagery eg,LANDSAT,AVHRR
Problem:
What do spectral values mean?
Digital Elevation Model:
An ordered array of numbers that represents the
spatial distribution of elevations above some
arbitrary datum in the landscape (eg,sea level)
Elevations sampled at discrete points over a
specified segment of the landscape
Three data networks:
1,Triangulated irregular networks
2,Contour-based networks
3,Grid-based
data stored at each point
on grid
ht
m)