- Slides: 30
Introduction – Landscape Ecology • Landscape Ecology: Study of landscape structure and processes. – Landscape: Heterogeneous area composed of several ecosystems. – Landscape Elements: Visually distinctive patches in an ecosystem.
Human Land Use Practices Ecosystem simplification:
Intensive Agriculture & Clean Farming
Timber Extraction & Fragmentation
Roads: Formation of Barriers in Landscapes
Formation of Terrestrial “Islands”
Habitat Fragmentation • Process of breaking contiguous unit into smaller pieces; area & distance components • Leads to: • Community & Ecosystem processes altered
#patches Patch isolation Patch size Edge
Habitat Fragmentation • area-sensitive species: species that require minimum patch size for daily life requirements • Edge effects: influence of factors from outside of a patch
Increased Edge Habitat
Increased Edge Habitat
Edge Effects • Habitat surrounding a patch can: - change abiotic conditions; e. g. , temp. - change biotic interactions, e. g. , predation Example of nest predation = edge effect of approximately 50 m into forest patch
Habitat Fragmentation • First-Order Effects: fragmentation leads to change in a species’ abundance and/or distribution
Habitat Fragmentation • Higher-Order Effects: fragmentation indirectly leads to change in a species abundance and/or distribution via altered species interactions
Habitat Fragmentation: Species. Specific Sensitivity? • Rare species = more vulnerable • Wide ranging species = large-area requirements • Species with reduced mobility = more vulnerable • Species with low fecundity (related to rarity? ) • Species with short life cycle (or multistage life cycle? )
Habitat Fragmentation: Species. Specific Sensitivity? • Interior-dependent species • Species vulnerable to human exploitation or disturbance • Specialist species?
Implications of Changes in Scale Insects sampled at 10 -m intervals for 100 m
Implications of Changes in Scale Insects sampled at 2000 -m intervals for 20, 000 m
Landscape Processes • Landscape structure influences processes such as the flow of energy, materials, and species between the ecosystem within a landscape.
Landscape Structure and Dispersal of Small Mammals
Habitat Patch Size and Isolation and Density of Butterfly Populations
Introduction – Geographical Ecology • Mac. Arthur defined geographical ecology as search for patterns of plant and animal life that can be put on a map. – Above level of landscape ecology
Island Area and Species Richness Species-Area Relationship
Island Biogeography • equilibrium model suggesting number of species occurring on an island represents a balance between immigration (in) and extinction (out) • Robert Mac. Arthur & E. O. Wilson
Equilibrium Model of Island Biogeography • Proposed rates of extinction on islands would be determined mainly by island size. – LG near islands will support highest number. – SM far islands will support lowest number. – SM near and LG far will support intermediate number.