1 / 39

Species abundance and diversity (Ch. 16)

Species abundance and diversity (Ch. 16). New Unit: Communities/Ecosystems. Community : Interacting species in defined area. Functional groups: subdivide organisms based on life history Guild : Organisms living in same fashion Animal Ex.: granivore guild. Harvester ants. K-rat.

mancia
Download Presentation

Species abundance and diversity (Ch. 16)

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. Species abundance and diversity (Ch. 16)

  2. New Unit: Communities/Ecosystems • Community: Interacting species in defined area. • Functional groups: subdivide organisms based on life history • Guild: Organisms living in same fashion • Animal Ex.: granivore guild Harvester ants K-rat

  3. New Unit: Communities/Ecosystems • Growth form: Combination structure + growth pattern. • Ex.: tree, shrub, graminoid, forb, climber

  4. Species Abundance • How express? • Log abundance (x-axis), number species in abundance category (y-axis) • Ex, plant species (% cover measures abundance) • Ex, bird species (counts measure abundance) Curve?

  5. Species Abundance • Normal (bell-shaped) curve • x-axis log scale: lognormal distributions

  6. Species Abundance • Often only part curve seen. • Why? Sample size. • Ex, moth community & sample size Tiger moth (Arctiidae) Sphingid moth (Sphingidae)

  7. Species Diversity • Two factors: • 1) Species Richness • Number species

  8. Species Diversity • Two factors: • 2) Species Evenness • Relative abundance of species

  9. Species Diversity • How integrate? • Diversity Index. Gives single number

  10. Species Diversity • Common: Shannon Wiener Index • Fish diversity lab! Ecology SU 2005

  11. Species Diversity • Shannon Wiener Index: s H´ = - pi logepi i=l • H´ = Value of index • pi = Proportion individuals of ith species • loge = Natural log • S = Number species in community

  12. Species Diversity • Ex: b greater diversity (same richness)

  13. Rank Abundance Curves • Rank abundance curves: • Relative abundance (proportional abundance: y-axis, log scale) vs. abundance rank (x-axis) • a vs. b

  14. Rank Abundance Curves • Ex: reef fish communities (Gulf of California)

  15. Rank Abundance Curves • Which more diverse? (Richness, evenness)

  16. Environmental Complexity • In general: diversity increases with environmental complexity (heterogeneity) • Ex, warblers (eat insects on trees) • Environmental complexity • = foliage volume

  17. Environmental Complexity • Foliage height diversity correlates positively bird species diversity

  18. Environmental Complexity • Hutchinson (1961): • Phytoplankton: simple environments, compete same nutrients • But many species coexist

  19. Environmental Complexity • Algal niches. • Ex, Diatoms (Protists, Phylum Bacillariophyta) • Photosynthetic • Cell walls: silicate

  20. Environmental Complexity • Coexistence depends on ratio silicate:phosphate • Different niches: different diatoms dominate

  21. Environmental Complexity • Do nutrients vary in “real world?” • Ex, Pyramid Lake, Nevada

  22. Environmental Complexity • Ex, Pyramid Lake, Nevada

  23. Environmental Complexity • Tropical rain forest diversity? • Amazon: 1 hectare (2.47 acres) up to 750 tree species USA has 850 native tree species!

  24. Environmental Complexity • Diversity due to: • 1) many species per community • 2) many communities per unit area • Complexity helps explain diversity

  25. Environmental Complexity • Relationship nutrients and rainforest richness? • Negative! • Competitive exclusion by best competitors

  26. Environmental Complexity • Reducing environmental complexity • When humans add nutrients (intentionally or not!) • Reduces diversity • Reduces limiting nutrients

  27. Environmental Complexity • Ex, English grassland fertilized since 1856!

  28. Environmental Complexity • Ex, N fertilization & ectomycorrhizal fungi diversity • N aerial pollutant (Alaska factory)

  29. Environmental Complexity • Contributes to diversity • But so does…disturbance • Define??

  30. Disturbance and Diversity • Disturbance: departure from “average?” • Sousa: • Discrete, punctuated, killing, displacement, or damaging of individuals that directly or indirectly creates an opportunity for new individuals to establish. • White and Pickett: • Relatively discrete event that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or physical environment.

  31. Disturbance and Diversity • Two major characteristics: • Frequency (how often) • Intensity (how severe) • Abiotic: fire, hurricanes, ice storms, flash floods • Biotic: disease, predation, humans

  32. Intermediate Disturbance Hypothesis

  33. Intermediate Disturbance • Ex: intertidal zone • Disturbance depends on boulder size.

  34. Intermediate Disturbance • Richness greater medium boulders

  35. Temperate Grasslands • American prairie dog disturbance….

  36. Disturbance

  37. Disturbance • Prairie dog control: reduced populations 98%

  38. Humans as disturbance • Human disturbance & diversity • Ex, chalk grasslands (Europe) • Graze livestock, cut hay • What happened when “protected”?

  39. Humans as a disturbance • Diversity dropped (Brachypodium dominated)

More Related