Aim: How do ecosystems change over time?

Are forest fires an ecosystems worst nightmare? Why or why not? Forest fires can destroy an ecosystem, but they also cause a resurgence of nutrients in the areas they burn. Although fire can tear down acres and acres of trees, it can also enrich the soil to let new vegetation grow.

Ecological Succession The process by which an ecosystem changes over time – often from a barren piece of land to a complex ecological community. CLIMAX COMMUNITY PIONEER PLANTS

Why did the grasses disappear? As time passes grasses grow & then get REPLACED by SHRUBS and eventually a FOREST will form. Why did the grasses disappear? The large shrubs and trees BLOCKED SUNLIGHT from reaching the grasses.

Look at the pictures of a mountain side taken over several years Look at the pictures of a mountain side taken over several years. Put them in the correct order. 4 1 3 2 5

Succession occurs BECAUSE: Each community changes the conditions so that they are more favorable to other organisms that replace them. For example, some types of trees need a lot of sun and their saplings cannot grow under the shade of their own species. They will be replaced by the types of trees whose saplings can grow in shade of other trees.

Ecological Succession in Ponds & Lakes: As time progresses, the Pond gets filled in with dead organic matter. The dead organic matter takes the place of the water in the lake. Eventually a forest forms where the pond once was.

What is the final state of ecological succession? A climax community with great Biodiversity!

Plant adaptation / succession 1:48

Destruction of Climax Communities *Fires, volcanic eruptions, tsunamis, deforestation, acid rain. *Their destruction often (but not always) means the birth of a NEW community via succession.

Primary Succession Primary Succession: The establishment of a new biological community in an area of bare rocks. (plants move in after lava flow or glacier retreats)

Secondary Succession Secondary Succession: occurs after a major disturbance happens and the soil still remains. (ex. after a forest fire).

Fire in the Forest 2:25