EEMB 2 Lecture Notes - Lecture 8: Species Evenness, Species Richness, Secondary Succession
15 Mar 2018
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Document Summary
Community: two or more populations living in the same geographic area. Most communities have only 3-5 trophic levels. Biomass: measure of weight of dry tissue (carbon) an organism contains. Energy: average of 10% of energy is transferred from one level to next. Ecological efficiency: trophic level transfer efficiency=production at trophic level n/production at trophic level n-1=(tl n/ tl n-1) Top-down effects: the abundance of lower trophic levels depends on the effects of consumers from higher trophic levels. Bottom-up effects: the abundance of higher trophic levels depends on factors such nutrients and prey availability from lower trophic levels. Species diversity: species richness + species evenness. Species richness=the number of species in a community. Species evenness=the relative abundance of species in a community. Diversity indices: designed to combine both species richness and evenness into an assessment of species diversity. Pi-proportion of individuals contributed to the total abundance. S-the total number of species in the community.
