Communities Change Over - Willis' · PDF fileCommunities Change Over Time Succession: a process of community development that ... Annuql and ure hardwood forest (oaks, hickory) 150

Communities Change Over Time

Succession: a process of community development that involves a changing sequence of species

• Starts with new land.

• Species land on new material and colonize (pioneer community).

• Starts with lichens, moss, and progresses to large trees after 1,000’s of years.

Primary Succession

1) Lichens: Can be N fixers Put Nitrate into soil for other plants to grow!

2) Small Shrubs and mosses (little roots), provide habitat

3) Young pine treesmore habitat

4) Mature hardwood and deciduous forests climax community

Secondary Succession

• Starts with already formed land.

• Species land on disturbed material.

• Disturbance usually caused by fires, storms, and man.

Fire Succession in Chaparral

• Needed for:

– Reproduction

– Clearing out competitors

– Germination (seed sprouting)

As Ecosystems Mature

• Increase in:1. Diversity & pop

numbers

2. System stability

3. Biomass

4. Nutrient Hold Capacity