Fire and Succession

http://www.fs.fed.us/photovideo/

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. http://www.marine.gov/

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

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

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