Spatial ecology II:
landscapes
Bio 415/615
Questions
1. Landscape ecology is the study of
spatial patterns… and what else?
2. What are three main agents of
landscape pattern?
3. What is GIS?
4. What are two examples of a
landscape element?
Landscape Ecology
Space: grain and extent
Landscapes are heterogeneous!
“Heterogeneity is not an annoyance that
complicates experimental designs, it is a
critical ingredient in explaining the stability of
ecological systems.” – Robert O’Neill (2001)
Landscape Ecology
vs. Island Biogeography and
Metapopulation biology
• Islands, populations, patches vary
• The matrix is not neutral
• The patch-matrix contrast is low or
high
• There are edge effects
• There are corridors, stepping stones,
and barriers
Landscape ecology
Landscape ecology is the study of the
causes, consequences, and dynamics of
spatial pattern in ecosystems
Like conservation biology, it is a relatively
new subfield (1980s).
Landscape
Landscapes are blocks of land that contain
this spatial pattern
Landscapes are defined either by natural
boundaries (watersheds, divides) or by
political or management boundaries
So, how BIG is a landscape?
“The view from a small airplane”
So, how BIG is a landscape?
REALLY ANY SCALE, but most often
used to refer to areas 10 to 100 km2
(2,500 to 25,000 acres) or larger
Depends on the process in question!
Wiens & Milne 1989 in
Landscape Ecology
Landscapes can be of any
resolution (grain) or extent.
Wiens & Milne 1989 in
Landscape Ecology
Landscapes can be of any
resolution (grain) or extent.
5m
GIS: THE tool of landscape
ecology
Geographic information systems (GIS) are
tools for capturing (GPS units),
managing & analyzing (software
products) data that are referenced to
spatial coordinates on Earth
(‘georeferenced’).
GIS example: lat-long
Treats the Earth as perfect
sphere, divides each hemisphere
into 90 degrees (plus divisions of
60 minutes and 60 seconds).
At equator, distance between
longitude lines is about 69 miles.
Syracuse:
45° 2' 53" N, 76° 6' 54" W
Robinson projection: note any
treatment of the Earth in 2D
must be distorted!
GIS example: Universal
Transverse-Mercator (UTM)
60 (distorted) world
zones; tropics distorted
the least
Syracuse: zone 18N
Easting: 412194 E
Northing: 4988893 N
Why UTMs? Values are
in meters.
Pattern & Process
The Landscape Ecology Mantra
Pattern & Process
The Landscape Ecology Mantra
Spatial pattern affects ecological
processes
. . . and . . .
Ecological processes affect spatial
pattern
This is why landscape ecology is not simply the study
of pattern (more akin to traditional geography).
Patterns: discrete and continuous
• Landscape ecology can be similar to
metapopulations, in that landscape
positions are discretized (made into
homogeneous patches)
• Landscapes can also be treated in more
continuous fashion (such as elevation or
contour maps, ie a surface)
• Both types are used in a GIS
Example of landscape modeling as
a continuous surface
• Modeling ground-level temperature in
mountainous terrain
Example: How landscapes control near-ground
temperature
A landscape model: how temperatures can be
predicted by factors derived from GIS
Level 1:
Minimum Temp = β0+ β1synoptic + β2radiation + β3cos(ωvt) +
β4sin(ωvt) + β5synoptic x radiation + ε
Level 2:
β0 = π00 + π01elevation + π0ilog(strdist) + π03log(tci)
β1 = π10 + π11log(strdist) + π11elevation + π13log(tci)
β2 = π20 + π21elevation + π22log(strdist)
β3 = π30 + π31elevation + π32log(strdist) + π33log(tci)
β4 = π40 + π41elevation + π42log(strdist) + π43log(tci)
β5 = π50
Mapping fine-scale GSMNP temperature
Run model for each pixel (about 4 million at 30 m grain)
Scales of variation
Mean annual temp
Patches & patch dynamics
Patch: A relatively homogeneous area defined
by some criterion
Patch dynamics: Processes of change (a)
within a patch, and (b) interactions among
patches on the landscape
Process of patch change
– Disturbance
– Recovery from disturbance (succession)
• Feedback to disturbance rate!
Patch dynamics
The importance of computer modeling to
simulate patch dynamics
Landscape Metrics
• Composition: Kinds of patches, matrix,
connections, barriers
• Size & Shape
– Perimeter/area ratio, Edge length
– Shape or boundary complexity
• Arrangement:
– Connectedness, dispersion, isolation
– Adjacency, contrast
Example of
discretizing a
landscape:
Mt LeConte
Great Smoky Mts
National Park
Let’s take a look
at a landscape:
Mt LeConte
Great Smoky Mts
National Park
S
W
Let’s take a look
at a landscape:
Mt LeConte
Great Smoky Mts
National Park
S
W
P
P
SW
P
P
P
P
Patches
Patches
Beetle
kills
Patches
Matrix
Patches
Barrier
Patches
Matrix
Landscape
ecology
Barrier
Patches
Matrix
Landscape
ecology
Barrier
Patches
Connectedness
Matrix
Landscape
Elements:
Patch
Matrix
Corridor
Chardon et al. 2003
Landscape
Elements:
Patch
Matrix
Corridor
Chardon et al. 2003
Landscape
Elements:
Patch
Matrix
Corridor
Chardon et al. 2003
Size, quality
Chardon et al. 2003
Connectedness,
Distance
Chardon et al. 2003
Corridor
Stepping
stone
Barrier
Chardon et al. 2003
Corridor
Stepping
stone
Barrier
Chardon et al. 2003
Corridor
Stepping
stone
Barrier
Chardon et al. 2003
Matrix,
Ecological
Contrast
Chardon et al. 2003
Landscape Metrics
• Composition: Kinds of patches, matrix,
connections, barriers
• Size & Shape
– Perimeter/area ratio, Edge length
– Shape or boundary complexity
• Arrangement:
– Connectedness, dispersion, isolation
– Adjacency, contrast
Edge Area
• Size effects edge
• Large areas have relatively shorter edge
lengths than small areas
3ha
6ha
Edge =
980m
3ha
Total Edge =
1386m
2ha
2ha
Total Edge =
1697m
2ha
The shape of a patch influences
amount of edge
All edge
Core &
edge
Turner et al. 1997: How fire size influences
vegetation response in Yellowstone NP
Small
burned
patches
recovered
faster than
large
burned
patches
Size of burned
patches
Landscape Metrics
• Composition: Kinds of patches, matrix,
connections, barriers
• Size & Shape
– Perimeter/area ratio, Edge length
– Shape or boundary complexity
• Arrangement:
– Connectedness, dispersion, isolation
– Adjacency, contrast
Central Smokies: low connectivity
Barrier
Patches
Matrix
Western Smokies: high connectivity?
AGENTS OF LANDSCAPE
PATTERN
CLIMATE
BIOTA
TOPOGRAPHY
SUBSTRATE
Landscape Flows
• What processes connect
patches or different landscape
positions?
Landscape Flows
•
•
•
•
•
•
Animal Dispersal
Wind movement
Hydrologic flows
Nutrient cycling
Insect outbreaks
Fire
Dynamic landscape models describe flows between landscape
positions over time, including how the environment (eg, soil
moisture) influences biota (eg plant growth) and vice-versa.
Process creates pattern
+ Fire often
increases
heterogeneity*
* (But not always!)
Post-fire mosaic, 1994 Rattlesnake
Fire, Chiricahua Mts., AZ
Process creates pattern
+ Fire often increases
heterogeneity*
- Succession sometimes
decreases
heterogeneity*
* (But not always!)
Blue Mts, California, at two periods
Pattern also affects process
+/- Fire spread
regulated by fuel
mass, moisture,
distribution
(“flammability”)
+/- Wind, humidity
influenced by
vegetation type and
structure