Community Ecology Patterns in Communities Chapter 20 Section 2 Pages

1.Species Richness 2.Species Evenness 3.Species- Area Effect Properties of a Community

1. Species Richness  Species Richness: the number of different species  Species richness increases, closer to equator

 Species Evenness: the relative abundance of each species 2. Species Evenness Which site is has greater species evenness?

 Species- Area Effect: larger areas contain more species than smaller areas 3. Species-Area Effect

 When species richness increases and species evenness increases:  Stability Increases (The ecosystem can withstand disturbances)  Disturbance – events that change communities, remove organisms, or alter resource availability Community Stability

Succession 20-2

 Succession: The sequential and gradual growth of a community  Two types:  Primary Succession  Secondary Succession Succession

 Primary succession occurs when land is first formed [hundreds of years]  Microbes, lichens and mosses must create soil before other plants can grow.  Pioneer species: first species to dominate early in succession (small and fast growing)

 Secondary succession: Succession starts over after the destruction of a climax community [about 150 years]  Climax Community: marked by the domination of long-lived species and great diversity  Occurs on sites that have already supported life

Which is primary and which is secondary?