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Human Resource Use

Human Resource Use. Human Values & Attitudes (Socio-political). 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.

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Human Resource Use

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  1. Human Resource Use Human Values & Attitudes (Socio-political)

  2. 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

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

  4. Intensive Agriculture & Clean Farming

  5. Timber Extraction & Fragmentation

  6. Formation of Terrestrial “Islands”

  7. Oceanic Island = Terrestrial Island ?????

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

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

  10. 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

  11. Formation of Terrestrial “Islands”

  12. Patch size #patches Patch isolation Edge

  13. What about aquatic systems?

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

  15. Increased Edge Habitat

  16. Increased Edge Habitat

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

  18. 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

  19. 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 • But can extend 100’s of meters….maybe km’s

  20. Edge Effects • How does patch size (in a landscape) & shape affect amount of edge? • Groups – give me a mathematical example with forested landscapes that have timber extraction via clearcutting

  21. Exponential vs. Logistic No DD DD All populations same All populations same No Spatial component

  22. Incorporating Space • Metapopulation: a population of subpopulations linked by dispersal of organisms • subpopulations separated by unsuitable habitat • subpopulations differ in population size & distance between

  23. Metapopulation Model p = habitat patch (subpopulation) c = colonization e = extinction

  24. Another Population Model • Source-sink Dynamics: grouping of multiple subpopulations, some are sinks & some are sources • Source Population = births > deaths = net exporter • Sink Population = births < deaths

  25. <1 >1 <1 Source-sink Dynamics

  26. Source-sink Dynamics

  27. Corridors

  28. Who Cares? • Why bother discussing these models? • Metapopulations & Source-sink Populatons highlight the importance of: • habitat & landscape fragmentation • connectivity between isolated populations • genetic diversity

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

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

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

  32. Differential Sensitivities to Habitat Alteration • Niche breadth (diet & habitat) – inverse relation • Range periphery = more sensitive (W & N) • Body size = mobility (allometric relation) • Social and territorial behavior (limited K) Swihart et al. 2003

  33. Ways to Manage 1) Featured Species Mgt • single species • particular purpose • e.g., white-tailed deer • could also include “umbrella species” and “flagship species” or “sensitive species”

  34. Ways to Manage 2) Species Richness Mgt • maintain diversity and certain # of each species (follow MVP concept) 3) Indicator Species Mgt • use a species (or group of species) to monitor environmental conditions • not necessarily managing for these spp. • bioindicators, biosentinels, “canary in coal mine”

  35. Ways to Manage 4) Guild Mgt or Life-Form Mgt • grouping of species based on use of same type of resources (e.g., foraging guilds)

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