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Fine-scale geomorphic pattern and biodiversity

Fine-scale geomorphic pattern and biodiversity. Duane A. Griffin and Phil Marquis Bucknell University Lewisburg, PA. Plant Biodiversity Patterns. Explanations. With Apologies: One More!. Competitive uncoupling hypothesis

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Fine-scale geomorphic pattern and biodiversity

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  1. Fine-scale geomorphic pattern and biodiversity Duane A. Griffin and Phil Marquis Bucknell University Lewisburg, PA

  2. Plant Biodiversity Patterns

  3. Explanations

  4. With Apologies: One More! • Competitive uncoupling hypothesis • Fine-scale habitat structure can disrupt interactions between individuals sharing a habitat. • If interactions are negative (competition, allelopathy, pathogen spread…), fragmentation should disrupt trajectories towards exclusion, thereby increasing diversity.

  5. How does this individual interact with others in its habitat?

  6. Direct interactions with immediate neighbors (competition)

  7. Direct interactions with immediate neighbors (competition) Mostly Deterministic Mostly Stochastic Seed dispersal and microsite colonization

  8. y = f(x)

  9. What if habitat patches are discrete and isolated at fine scales?

  10. Colonization neighborhood remains the same

  11. Resource competition neighborhood is smaller

  12. y = f(x)

  13. Individual-Based Spatially Explicit Reaction-Diffusion Model A A B A B A A B A Testing: GeoSim Seed Dispersal Colonization Lottery Diffusion Reaction Competition Seed Production

  14. Colonization Lottery Seed Dispersal Seed Production Competition

  15. Colonization Lottery Seed Dispersal Seed Production Competition

  16. Colonization Lottery Seed Dispersal Seed Production Competition

  17. Colonization Lottery Seed Dispersal Seed Production Competition

  18. Colonization Lottery Seed Dispersal Seed Production Competition

  19. Colonization Lottery Seed Dispersal Seed Production Competition

  20. Colonization Lottery Seed Dispersal Seed Production Competition

  21. 1 2 3 4 5 6 7 8 9 Landscapes

  22. Experiment • 2 species: “a” & “b” • Asymmetric competition (αab = 10, α ba = 1) • Symmetric fecundity and dispersal parameters • 100 runs in each of: • 9 unfragmented landscapes • 9 fragmented landscapes • Aggregation Index (Landscape statistics: APACK v. 2.23 (Mladenoff and DeZonia 2004)

  23. Results: Area Effect

  24. Results: Time to Extinction

  25. Results

  26. Conclusion Fine-scale habitat fragmentation facilitates coexistence of competitively asymmetric species. In a digital landscape, at least.

  27. Does this happen in real landscapes?

  28. Yes.

  29. Fragmentation, Diversity, Space, and Time • Fragmentation disrupts the processes governing membership in ecological communities. • Negatively • Positively • Allopatric speciation • Competitive uncoupling (?)

  30. + Allopatric speciation ? “Spatial insurance” (Metapopulations) + − • Habitat fragmentation → relaxation + − Uncoupling Fragmentation, Diversity, Space, and Time Time Space

  31. Might Uncoupling Emerge at Broader Scales?

  32. Might Uncoupling Emerge at Broader Scales?

  33. Some Implications • Rare species may gain refuge in habitats with fine-scale fragmentation. • Habitats with fine-scale fragmentation may provide immigration points for exotic species. • It’s worth looking into this…

  34. Acknowledgements • Office of the President, Bucknell University • Office of the Dean, Bucknell University College of Arts and Sciences • Bryn Scriver and John Stoddard

  35. Thank you.

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