Disturbance and Succession NOTES

I. Disturbance An event that causes loss of life in a community Measured by scale, intensity, and frequency Moderate disturbance can increase diversity in communities

II. Population Growth (post-disturbance and otherwise) Carrying Capacity: maximum population size an ecosystem can sustain Limiting Factor/ Resource: factors that influence carrying capacity limiting factors carrying capacity # of organisms r-strategists K-strategists time

III. Ecological Succession Many species of organisms in an area is a community. 1. An existing______________of is replaced by a different community over periods of time ranging from a few decades to thousands of years. community organisms Secondary succession Primary succession

III. Ecological Succession Climax stage III. Ecological Succession K-strategists Later seral stages Early seral stages r-strategists Mid seral stages Pioneer species

III. Ecological Succession 2. Disturbance/ uninhabited area lichens, (produce acids to break down rocks), produce a thin soil, In primary succession only mosses, (change soil) , weeds, grasses, (pioneer species), perennial herbs, shrubs, trees, insects, birds, animals

III. Ecological Succession 3. Climax community – stable collection of organisms – which reach a stage stable than those that preceded. Nature of the climax community depends on climate: varies from rainforest to shrubland to grassland, etc. more

III. Ecological Succession 4. Trends in many successions Change in community structure: Replacement of opportunistic, early-stage (r-strategists) with late-stage (K-strategists) Increased nutrients available. Increased biomass (living material) Increase in diversity (especially with small, regular disturbances) Increased complexity (i.e. in food web) Increased stability between photosynthesis (producers) and respiration (consumers)