LECTURE 21
CH 25 LANDSCAPE ECOLOGY
MAJOR CONCEPTS
1. Landscape ecology: relationship between large-scale spatial pattern and ecological
processes.
2. Landscape ecology includes human + natural influences, past + present.
2. Landscape structure includes size, shape, composition, number, position of patches.
4. These features affect species abundance, richness, and interactions, as well as
movement of nutrients and energy.
4. Populations exist in heterogeneous landscapes. Corridors and stepping stones can
offset fragmentation effects.
6. Metapopulations are discrete subpopulations linked by movements of individuals.
5. Movement of individuals maintains the spatial and genetic coherence of populations.
6. Different species perceive the landscape at different scales and depend on different
scales for different activities and at different life history stages.
Landscape Ecology: 25.1
Study of relationship between spatial patterns and ecological processes over a range of
spatial scales. Includes natural + human influences, past + present 25.2, 3, 4, 5
Tools to quantify landscape mosaics: GPS, GIS, airplanes, satellites with remote sensing
use different wavelengths to highlight different features 25.6, 25.7, 25.8
Landscape structure: size, shape, number, and position/pattern of patches.
: influences flow of energy, materials, and species across a landscape.
Habitat heterogeneity (patches) affects populations, species interactions, community
dynamics
Fragmentation: creation of habitat patches of different sizes and shapes
Creates edges
Smaller fragments have greater proportion of area as edge habitat 25.10
Changes area: How large a fragment is necessary to maintain a population? 25.9
Creates fragments of different shapes: round has lowest edge/interior ratio 25.12
Size and shape affect species abundances, species diversity, and interactions 25.11
Edge effects on organisms with different levels of sensitivity to edge vs.
interior (edge specialists) and species interactions (e.g nest parasitism)
Patches create a mosaic (pattern) within a background matrix.
Spatial dynamics of populations within mosaic
Habitat patchiness (heterogeneity)  3 models of populations 10.18
Metapopulation: matrix is unsuitable for species; migration between habitats
Source-sink: source (B>D  emigration); source (D>B  immigration)
Landscape: patches offer different resources; species uses multiple patches
suitability of landscape influences migration between patches
Metapopulation: subpopulations in different patches with some migration between 12.14
What determines if matrix is a barrier to movement?
Distance between patches, nature of matrix, mobility of species
Small, isolated populations with no migration have different genetic structure
Patches differ in size, habitat quality, degree of isolation (corridors) 10.22, 10.23
Metapopulation dynamics depends on
Birth and death of subpopulations
Migration between patches
Colonization to form new subpopulations
Extinction of existing subpopulations
Connectivity allows migration (gene flow) and maintain population cohesion 10.2
promotes species turnover 25.13; offsets some aspects of fragmentation
Corridors - continuous connection between patches
Stepping stones - small intervening patches between large patches of
favorable habitat
Quality of intervening matrix between patches determines movement
Factors determining patch occupancy 12.15
Patch size
Patch isolation
Different organisms perceive the landscape at different scales 25.14, 25.15
Grain (degree of resolution)
Size of landscape (extent)
Organisms depend on different landscape scales for different activities and
at different life history stages.
Summary: 1-11