ch3 communities, biomes, ecosystems

Communities, Biomes, & Ecosystems

CH3

LIMITING FACTOR: Any biotic or abiotic Factor that limits the numbers of a species. Food, water, shelter, predation

RANGE OF TOLERANCE: For any environmental factor (biotic or abiotic), there is always an upper & lower limit that any species can live between.

ECOLOGICAL SUCCESSIONEcosystems may change, so that one community may replace another because of changes in biotic and abiotic factors.

Primary Succession: A community is established on exposed rock that does not have any soil. Pioneer species break down rock, make soil. Other species then move in, until a stable, mature Climax Community is established.

Pioneer Species breaking rock down with roots and acids to make soil.

Secondary Succession: A disturbance destroys the community, which slowly reestablishes itself on the remaining topsoil.

3.2 BIOMES: Zones classified by plant communities; determined by Latitude, Altitude, and Climate. Variations in temperature, sun exposure, and water availability result in selective pressures that determine which plants may grow in a particular area.

PROPERTIES OF COMMUNITIES

Species richness: The number of species a community contains. Varies with latitude. Generally, equatorial regions have more species, with numbers reducing as you approach the poles.

Species-Area effect: Larger areas generally contain more species than smaller ones. Greater diversity of habitats can support more species. Reducing size of habitat will reduce number of species, and number of individuals within surviving species.

PROPERTIES OF COMMUNITIES

Species interactions & richness: Predators prevent competitive exclusion among their prey. Superior competitors cannot become dominant if subject to predation.

Community Stability: Species rich areas are more resistant to change; in a disturbance, less species are lost, and recovery time is faster.