COMMUNITY ECOLOGY cont

pp. 405-410

Species (organism)

Population

Community (interaction of different species)

Ecosystem

Biosphere

PROPERTIES OF A COMMUNITY

• Species Richness• Species evenness• Species- Area Effect

Species Richness: # of different types of species

• varies with latitude (closer to equator the more species)

• more sun, better climate stability

• Species evenness: the abundance of each species

• ↑species richness and ↑ evenness: ↑ stability (ability to withstand disturbances in the ecosystem)

• Species- Areas Effect: larger areas contain more species than smaller areas

KEYSTONE SPECIES • most dominant species

in the community• Dictates community

structure• Demonstrated by

removal of keystone species from community

What would happen to the species richness if the keystone species is removed from the ecosystem?

SUCCESSION

• Sequential and gradual growth of a community• Two types: primary and secondary

• Primary succession occurs when land is first formed.

1. Microbes, lichens and mosses must create soil before other plants can grow.

2. Pioneer species: first species to dominate early in succession (small and fast growing)

• Secondary succession occurs when succession must start over after the destruction of a climax community (marked by the domination of long-lived species and great diversity).

- takes place on sites that have already supported life

Homework

• Read pp 405-410• P 410 #1-5, 8• Worksheet #5