1. Notice the rings of very early pioneer stages on the outer rim and more advanced early seral species. Early seral plants are often annual, herbaceous, and have invasive characteristics.

3. Plant Community Succession (Initial Ideas -- Clements)
Above average rainfall
Successional tendency
Succession
Climax or Potential Natural Community
Drought
Grazing Pressure
Retrogression
Natural Potential
When a perturbation (disturbance or stress as we will refer to it) causes a major ecosystem function to deviate from its normal operating range, the degree of deviation is a measure of relative resistance stability, whereas the time required for recovery is a measure of relative resilience stability.
Notes from Steve Bunting – University of Idaho
Pioneer/Early
Late
Seral Stage

5. Example - Sagebrush Steppe States
Grassland
Open
Sagebrush
Closed
Depleted
Annual Grass
Dominated State
Threshold
Grassland
Open
Sagebrush
Closed
Depleted
In some areas of the Great Basin we can observe a third state- that dominated by annual grasses such as cheatgrass or ripgut brome. The movement back into either the sagebrush state or the woodland state is difficult in these environments.