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Introduction – Landscape Ecology

Introduction – Landscape Ecology

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Introduction – Landscape Ecology

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  1. 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.

  2. Human Land Use Practices • Ecosystem simplification:

  3. Intensive Agriculture & Clean Farming

  4. Timber Extraction & Fragmentation

  5. Roads: Formation of Barriers in Landscapes

  6. Formation of Terrestrial “Islands”

  7. Habitat Fragmentation • Process of breaking contiguous unit into smaller pieces; area & distance components • Leads to: • Community & Ecosystem processes altered

  8. Patch size #patches Patch isolation Edge

  9. 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

  10. Increased Edge Habitat

  11. Increased Edge Habitat

  12. 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

  13. Habitat Fragmentation • First-Order Effects: fragmentation leads to change in a species’ abundance and/or distribution

  14. Habitat Fragmentation • Higher-Order Effects: fragmentation indirectly leads to change in a species abundance and/or distribution via altered species interactions

  15. 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 multi-stage life cycle?)

  16. Habitat Fragmentation: Species-Specific Sensitivity? • Interior-dependent species • Species vulnerable to human exploitation or disturbance • Specialist species?

  17. Implications of Changes in Scale Insects sampled at 10-m intervals for 100 m

  18. Implications of Changes in Scale Insects sampled at 2000-m intervals for 20,000 m

  19. Landscape Processes • Landscape structure influences processes such as the flow of energy, materials, and species between the ecosystem within a landscape.

  20. Landscape Structure and Dispersal of Small Mammals

  21. Habitat Patch Size and Isolation and Density of Butterfly Populations

  22. Introduction – Geographical Ecology • MacArthur defined geographical ecology as search for patterns of plant and animal life that can be put on a map. • Above level of landscape ecology

  23. Island Area and Species Richness Species-Area Relationship

  24. Island Biogeography • equilibrium model suggesting number of species occurring on an island represents a balance between immigration (in) and extinction (out) • Robert MacArthur & E.O. Wilson

  25. 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.