BIO-8 Lecture Notes - Lecture 22: Intermediate Disturbance Hypothesis, Secondary Succession, Biocoenosis
Document Summary
Suggests that communities are always developing toward a climax (old growth) equilibrium: equilibrium depends on climate, edaphic"s, and takes a long time. Gleason: individualistic change, just want to reproduce and attain resources. But what happens to an ecosystem following a disturbance: depends on the ecosystem, and on the disturbance frequency, prairies: maintained by fires every year (low biomass) and grazing. Low levels of disturbance allow competition to reduce diversity. Chronological change of a biotic community in a newly established area following a disturbance (sanitizes environment) (volcano, flood etc) Chronological change of a biotic community following a disturbance (life still. Secondary succession present in roots) (forest fires) 2 years: some regrowth of organisms not killed to root level. 7 years: reduced visibility due to growth of trees. Early successional species are strong dispersers/competitors for nutrients. Early colonizers provide a benefit for later successional species: increase soil nutrients.
