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
Reiners et.al. studied changes in plant diversity during succession.
Total number of plant species increased with plot age.
Species richness increased rapidly in early years of succession and more slowly during later stages.

4. Primary Succession at Glacier Bay

5. Model of Ecosystem Recovery
Biomass Accumulation Model
Reorganization (10-20 yrs)
Forest loses biomass and nutrients.
Aggradation (100+ yrs)
Ecosystem reaches peak biomass.
Transition
Biomass declines from peak.
Steady-State
Biomass fluctuates around mean.

6. 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.

8. Humboldt hiked up Mt. Chimborazo to an elevation of 5878m.
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

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

10. Clements idea of distribution
Are populations organized into discrete communities?
Clements idea of distribution

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