Section 4: How Ecosystems Change Kelcie, Mimi, Jimmy, Michael, Catherine & Tommy

Ecological Succession is a gradual process of change and replacement of the types of species in a community.

Primary Succession Type of succession that occurs on a surface where no ecosystem has ever been before It can occur on rocks, cliffs, sand dunes and more It is the first stage of succession It takes much longer than secondary succession It can only occur where life has NEVER been present- bacteria and lichen are often the first species to take over because they can live without soil. When lichen break down rock, and that mixes with water, soil begins to form.

Secondary Succession The second stage of succession It occurs on a surface where an ecosystem has existed in the past. One community takes over a space and flourishes where a previous community has lived. Reasons for a new ecosystem to start to grow include fires, human disruption, floods, earthquakes and volcanic eruptions.

Pioneer species- this is the first species to take over an area that is currently uninhabited. It creates an environment that is livable for other species and for an ecosystem to grow from. A climax community is a finalized environment that is stable and can survive on its own. A climax community with thrive and stay stable until disturbed.

Forest Fires Forest fires are caused by several reasons including lightening, droughts and extreme heat from the sun. In some habitats they are necessary parts of the communities stability. Minor fires burn away dead wood and brush that is taking over. They clean up the forest and prevent extra brush that could contribute to uncontrollable fires in the future. New plants after fires feed some species.

Farm Land and Succession When a farmer abandons a farm field, old-field succession takes place and grasses and weeds begin to grow where the land has been abandoned. Over time, what used to be farmland is transformed into an environment that has perennial grasses, shrubs, and trees.