LANDSCAPE ECOLOGY
SREM 3011
LECTURE 9
Dr Brendan Mackey
Department of Geography
The Australian National University
Scale provides concepts and tools for
integrating the effects of environmental
processes on the occupancy of landscapes
by plants and animals
If we do not think about scale,then we risk
being captive of scale imposed by human
senses
Ecology is a matter of primary human experience
Landscape texture?horizontalvertical?
Scale at which structures occur in the landscape
Structures = components of a system
At?landscape? to?regional?,scales”,vegetation
is a major component of,structure”
,species composition,canopy height,vertical
organization,leaf physiognomy
,particularly important with respect to the
occupancy of landscapes by animals
Texture = measure of the complexity of landscape
structure
= complexity in the spatial configuration of
vegetation (eg,?patches?)
Fine texture = many,small patches with convoluted
perimeters
Coarse texture = a few large patches with simple
perimeters
Vertical structure of vegetation fine/coarse textured
Fractal dimension (Horizontal texture)
- a measure of landscape complexity
landscape texture
- based on measurement of length of boundaries of
entities forming patterns
- (1) Length of measuring unit or?segment?
(2) Total length of perimeter
OR
Maps of Britain capture more detail as the length segments used for the outline are
shortened,With the longest straight line segments,Britain appears only as a triangle,
As the straight segments of the outline are made shorter,more and more detail emerges
while the length of the coastline increases,For infinitely small straight line segments,the
coastline of Britain is infinitely long.
The more complicated is the outline of a shape,the greater the total perimeter will
increase as the line segments used to outline it are made shorter,The upper shape A is
simple and so has a small ratio estimated perimeters with long and short estimator seg-
ments (1.1041),The lower shape is complicated so revealing a greater increase in peri-
meter with short estimator segments to yield a larger ratio (1.1611).
If a log-log plot of the length of the estimators and the length of the total
perimeter is a straight line,then the structure is fractal.
In the Koch diagram,straight line segments are divided into four segments with a point
emerging in the middle of each straight line,Subsequent straight lines of shorter lengths
can then be further divided into lines with a point in the middle,This system is self-
similar,in that successively finer-grained patterns follow smaller scale versions of the
original pattern,The fractal dimension of a Koch diagram is 4/3.
Self-similar pattern
If the degree of complexity of the outline of a form is different at different scales,then the
log-log plot of line segment against perimeter will bend at the scale at which the comple-
xity of the pattern changes,At that point the fractal dimension itself changes,The outlines
are merely to show simple and complex patterns at different scales; the differently scaled
patterns are so specifically scaled that the shapes are not strictly fractal,but are to illus-
trate the point that large and small scale patterns can readily exhibit different degrees of
complexity
Krummel et al,(1987) discovered that the outline of forests in the United States have
small fractal dimension at small scale and a larger fractal dimension at large scale,Small
scale appears to indicate human activity while large scale seems under topographic
control,At a point where the fractal dimension changes,the system has a middle number
specification and is likely to be unpredictable.
Landscape texture is important because biotic-
response to the environment is a scale-dependent
phenomena
An organism?s spatial grain varies from taxa to taxa
and between trophic levels
Animals do migrate but once they?ve arrived,?home
range? is equally important as it is for sedentary
organisms
Home range distance/area covered by an animal
to obtain required resources for
shelter,energy,nutrients,repro-
duction
Home range size (measured in ha) vs body mass (measured in grams) of mammals.
= simple least squares regression,- - - - - = principal axis correlation
Therefore,amount of distance/area an animal has to
cover in a landscape is a function of:
1,Trophic level
2,Body size
3,Amount of required resources
available in the landscape
> trophic level +
> body size +
< resources/ha > distance travelled
Key point,the amount of resources available for
an animal depends on
(1) landscape texture and
(2) animal?s spatial grain
Spatial grain and landscape texture
horizontal and vertical
texture
# organisms with different
spatial grains
biodiversity!
Horizontal and vertical texture of landscape is
strongly controlled by the primary environmental
regimes
ie,PERs control what plant species are
present and the structure and physiognomy
of the vegetation
Texture therefore results from interactions between
PERs and disturbance
PERs
ANIMALS
SUBSTRATECLIMATE
TOPOGRAPHY
VEGETATION
/PLANTS
LANSCAPE
TEXTURE
In applying small scale models (eg,cellular photosynthesis rates given conditions of CO2,PAR and
temperature etc.) at landscape level several levels of resource heterogeneity are encountered.
A,heterogeneity between mesophyll cells,B,heterogeneity across a leaf surface,C,heterogeneity
of resources across a plant,D,heterogeneity of resources between plants across the landscape.
The result of heterogeneity is that when data at broader scales are applied as mean values to a
cellular-scale model,problems may arise,It is at landscape and larger scales that the most pressing
issues of resource management occur,Models may involve several scales of behaviour.
(Allen & Starr 1982,O’neill et al,1986)
SREM 3011
LECTURE 9
Dr Brendan Mackey
Department of Geography
The Australian National University
Scale provides concepts and tools for
integrating the effects of environmental
processes on the occupancy of landscapes
by plants and animals
If we do not think about scale,then we risk
being captive of scale imposed by human
senses
Ecology is a matter of primary human experience
Landscape texture?horizontalvertical?
Scale at which structures occur in the landscape
Structures = components of a system
At?landscape? to?regional?,scales”,vegetation
is a major component of,structure”
,species composition,canopy height,vertical
organization,leaf physiognomy
,particularly important with respect to the
occupancy of landscapes by animals
Texture = measure of the complexity of landscape
structure
= complexity in the spatial configuration of
vegetation (eg,?patches?)
Fine texture = many,small patches with convoluted
perimeters
Coarse texture = a few large patches with simple
perimeters
Vertical structure of vegetation fine/coarse textured
Fractal dimension (Horizontal texture)
- a measure of landscape complexity
landscape texture
- based on measurement of length of boundaries of
entities forming patterns
- (1) Length of measuring unit or?segment?
(2) Total length of perimeter
OR
Maps of Britain capture more detail as the length segments used for the outline are
shortened,With the longest straight line segments,Britain appears only as a triangle,
As the straight segments of the outline are made shorter,more and more detail emerges
while the length of the coastline increases,For infinitely small straight line segments,the
coastline of Britain is infinitely long.
The more complicated is the outline of a shape,the greater the total perimeter will
increase as the line segments used to outline it are made shorter,The upper shape A is
simple and so has a small ratio estimated perimeters with long and short estimator seg-
ments (1.1041),The lower shape is complicated so revealing a greater increase in peri-
meter with short estimator segments to yield a larger ratio (1.1611).
If a log-log plot of the length of the estimators and the length of the total
perimeter is a straight line,then the structure is fractal.
In the Koch diagram,straight line segments are divided into four segments with a point
emerging in the middle of each straight line,Subsequent straight lines of shorter lengths
can then be further divided into lines with a point in the middle,This system is self-
similar,in that successively finer-grained patterns follow smaller scale versions of the
original pattern,The fractal dimension of a Koch diagram is 4/3.
Self-similar pattern
If the degree of complexity of the outline of a form is different at different scales,then the
log-log plot of line segment against perimeter will bend at the scale at which the comple-
xity of the pattern changes,At that point the fractal dimension itself changes,The outlines
are merely to show simple and complex patterns at different scales; the differently scaled
patterns are so specifically scaled that the shapes are not strictly fractal,but are to illus-
trate the point that large and small scale patterns can readily exhibit different degrees of
complexity
Krummel et al,(1987) discovered that the outline of forests in the United States have
small fractal dimension at small scale and a larger fractal dimension at large scale,Small
scale appears to indicate human activity while large scale seems under topographic
control,At a point where the fractal dimension changes,the system has a middle number
specification and is likely to be unpredictable.
Landscape texture is important because biotic-
response to the environment is a scale-dependent
phenomena
An organism?s spatial grain varies from taxa to taxa
and between trophic levels
Animals do migrate but once they?ve arrived,?home
range? is equally important as it is for sedentary
organisms
Home range distance/area covered by an animal
to obtain required resources for
shelter,energy,nutrients,repro-
duction
Home range size (measured in ha) vs body mass (measured in grams) of mammals.
= simple least squares regression,- - - - - = principal axis correlation
Therefore,amount of distance/area an animal has to
cover in a landscape is a function of:
1,Trophic level
2,Body size
3,Amount of required resources
available in the landscape
> trophic level +
> body size +
< resources/ha > distance travelled
Key point,the amount of resources available for
an animal depends on
(1) landscape texture and
(2) animal?s spatial grain
Spatial grain and landscape texture
horizontal and vertical
texture
# organisms with different
spatial grains
biodiversity!
Horizontal and vertical texture of landscape is
strongly controlled by the primary environmental
regimes
ie,PERs control what plant species are
present and the structure and physiognomy
of the vegetation
Texture therefore results from interactions between
PERs and disturbance
PERs
ANIMALS
SUBSTRATECLIMATE
TOPOGRAPHY
VEGETATION
/PLANTS
LANSCAPE
TEXTURE
In applying small scale models (eg,cellular photosynthesis rates given conditions of CO2,PAR and
temperature etc.) at landscape level several levels of resource heterogeneity are encountered.
A,heterogeneity between mesophyll cells,B,heterogeneity across a leaf surface,C,heterogeneity
of resources across a plant,D,heterogeneity of resources between plants across the landscape.
The result of heterogeneity is that when data at broader scales are applied as mean values to a
cellular-scale model,problems may arise,It is at landscape and larger scales that the most pressing
issues of resource management occur,Models may involve several scales of behaviour.
(Allen & Starr 1982,O’neill et al,1986)
