Fire and Succession

One Year Later

Thirteen Years Later

Keystone Species A single species that maintains biotic structure of the ecosystem Pisaster ochraeceus - a starfish that feeds on mussels, keeping them from blanketing the rocks.

Competition: Intraspecific Territoriality: defense of a resource against individuals of the same species –Examples of wolves and songbirds –Results in priority access and use of resources How do wolves and songbirds establish territory?

Competition: Interspecific Grassland contains plants with both fibrous and tap roots Coexist by accessing resources from different soil levels

Succession and Disturbance Ecological succession: the orderly and progressive replacement of one community type by another until a climax stage is reached. –Primary - no previous biotic community –Secondary - previously occupied by a community –Aquatic - transition from pond or lake to terrestrial community

Primary Succession

Mosses invade an area and provide a place for soil to accumulate. Larger plants germinate in the new soil layer resulting in additional soil formation. Eventually shrubs and trees will invade the area.

Secondary Succession

Aquatic Succession

This used to be a lake!

Fire and Succession Fire climax ecosystems: dependent upon fire for maintenance of existing balance; e.g., grasslands, pine, and redwood forests What significance does this have for humans and where they live?

Resilience in Ecosystems

Resilience Mechanisms After a Forest Fire Nutrient release to soil Regrowth by remnant roots and seeds Invasions from neighboring ecosystems Rapid restoration of energy flow and nutrient cycling