1 / 71

Introduction – Landscape Ecology

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. Vancouver Island marmot ( Marmota vancouverensis ). ~100 left.

Télécharger la présentation

Introduction – Landscape Ecology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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. Vancouver Island marmot(Marmota vancouverensis) ~100 left Isolated from hoary and Olympic marmots

  3. Vancouver Island marmot(Marmota vancouverensis) Natural tree succession

  4. Vancouver Island marmot(Marmota vancouverensis) • Logging – disjunct patches • - max. dispersal = 7 km • Climate • Prey-Predator Dynamics

  5. Human Land Use Practices • Agriculture • Suburban Development • Let’s pick on Indiana: • 97% of land in state = privately-owned • In central Indiana, • 70+% of land in row crop • <10% in forest • Urban sprawl intensifying

  6. Human Impacts • Ecosystem simplification: elimination of species from food webs via human alterations to land • Example: vertebrate communities in ag. landscapes

  7. Intensive Agriculture & Clean Farming

  8. Timber Extraction & Fragmentation

  9. Roads: Formation of Barriers in Landscapes

  10. Formation of Terrestrial “Islands”

  11. Habitat Fragmentation • Process of breaking contiguous unit into smaller pieces; area & distance components • Leads to: • < remnant patch size • > edge:interior ratios • > patch isolation • < connectivity • Community & Ecosystem processes altered

  12. Formation of Terrestrial “Islands”

  13. Habitat Loss vs. Habitat Fragmentation

  14. Patch size #patches Patch isolation Edge

  15. What about aquatic systems?

  16. What about aquatic systems? Con.Bio 12(6)

  17. 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

  18. Increased Edge Habitat

  19. Increased Edge Habitat

  20. 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

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

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

  23. HABITAT FRAGMENTATION Predators - Abundance - Distribution - Foraging Behaviors + Ground-Nesting Birds - Abundance - Distribution – – – Avian Competitors Avian Prey Brood Parasites + + Parasites - Abundance - Distribution REPRODUCTIVE SUCCESS

  24. 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?)

  25. Habitat Fragmentation: Species-Specific Sensitivity? • Ground-nesting birds may be more vulnerable (30-60% reduction in last 25 yrs) • Interior-dependent species • Species vulnerable to human exploitation or disturbance • Specialist species?

  26. Habitat Fragmentation: Species-Specific Sensitivity? • Generalizations are a good start • (= hypotheses?), but a little more complex than that……

  27. Gehring and Swihart. 2003. Biological Conservation 109:283-295

  28. Spatial and Temporal Ecology of Raccoons Gehring et al. In prep.

  29. Swihart et al. 2003. Diversity and Distributions 9:1-8.

  30. Brown and Litvaitis. 1995. Canadian Journal of Zoology 73:1005-1011

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

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

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

  34. Landscape Structure and Dispersal of Small Mammals

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

  36. Organisms and Landscape Structure • African elephants knock down tress. • Change woodland to grassland. • Kangaroo Rats dig burrow systems that modify soil structure and plant distributions. • Beavers cut trees, build dams and flood surrounding landscape. • At one time, beavers modified nearly all temperate stream valleys in Northern Hemisphere.

  37. Organisms and Landscape Structure • Johnston and Naiman documented substantial effects of beavers on landscape structure. • Over 63 yrs, area created by beavers increased from 200 ha to 2,661 ha. • Changed boreal forest landscape to complex mosaic. Skip

  38. Organisms and Landscape Structure • Beaver activity between 1927-1988 increased quantity of most major ions and nutrients in impounded areas. Three possible explanations: • Impounded areas may trap materials. • Rising waters captured nutrients formally held in vegetation. • Habitats created by beavers may promote nutrient retention by altering biogeochemical processes. Skip

  39. Introduction – Geographical Ecology • MacArthur defined geographical ecology as the search for patterns of plant and animal life that can be put on a map. • Above level of landscape ecology. • Vast breadth • Chapter only focuses on a few aspects.

  40. Oceanic Island = Terrestrial Island ?????

  41. Island Area and Species Richness • Preston found fewest bird species live on smallest islands and most species on largest islands. • Nilsson et.al. found island area was best single predictor of species richness among woody plants, carabid beetles, and land snails. Skip

  42. Island Area and Species Richness

  43. Species-Area Relationship • S = cAz • S = # of species • A = island area • Positive correlation between island size & number of species • Applies to terrestrial “islands” also

  44. Habitat Patches on Continents: Mountain Islands • As Pleistocene ended and climate warmed, forest and alpine habitats contracted to the tops of high mountains across American Southwest. • Woodlands, grasslands, and desert scrub, invaded lower elevations. • Once continuous forest converted to series of island-like fragments associated with mountains: Montane. Skip

  45. Lakes as Islands • Lakes can be considered as habitat islands. • Differ widely by degree of isolation. • Tonn and Magnuson found the number of species increases with the area of an insular environment. • Barbour and Brown found positive relationship between area and fish species richness. Skip

  46. Lakes as Islands Skip

More Related