1 Succession and Stability

2 Introduction Succession: Gradual change in plant and animal communities in an area following disturbance. – Primary succession on newly exposed geological substrates. – Secondary succession following disturbance that does not destroy soil. Climax Community: Late successional community that remains stable until disrupted by disturbance.

3 Primary Succession at Glacier Bay

4 Community and Ecosystem Stability Stability: Absence of change. Resistance: Ability to maintain structure and function in face of potential disturbance. Resilience: Ability to recover from disturbance.

5

6 Are populations organized into discrete communities? Humboldt hiked up Mt. Chimborazo to an elevation of 5878m. He recorded vegetation along the elevational gradient. What order? * Ferns and palms * Grass and lichens * Oak forest * Broad-leaved herbaceous plants * Evergreen shrubs

7 Clements and others (ex. Kuchler map) felt communities were essentially superorganisms Are populations organized into discrete communities?

8 Clements idea of distribution Are populations organized into discrete communities?

9 Gleason argued for subtle transitions as opposed to sharp boundaries. He suggested a continuum. Are populations organized into discrete communities?