Ecosystem Changes February 12, Unit 2 How Ecosystems Change. Succession

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1 Unit 2 How Ecosystems Change Succession Ecological succession is a gradual process of change and replacement of the types of species in a community. It may take hundreds or thousands of years.

2 Succession The ecosystems that exist today did not always exist as they appear. Ecosystems change over time. ex: Prairies become deserts Bare rock becomes a forest Factors that Cause Change What do you believe can cause an ecosystem to change over time? Natural phenomena such as volcanic eruptions and glaciers can reduce ecosystems to bare rock. Other phenomena such as fires and floods will destroy an ecosystem but leave soil in place. Certain human activities such as mining can also change ecosystems.

3 Primary succession begins with bare rock. The first organisms to establish themselves are known as a pioneer species. Drag the lichen onto the bare rock. Pioneer organisms, such as lichen can grow on bare rock. Lichen are organisms made of a symbiotic relationship between algae and fungi. The algae can photosynthesize while the fungi can attach themselves to rock and draw minerals from the ground. Pioneer organisms transform the environment just enough to allow other organisms to establish themselves there. Use the green marker to draw some moss on the bare rock. Small cracks in the rock created by lichen and other pioneer organisms allow mosses to attach themselves and grow. The roots of the moss will increase the size of the cracks. Water will infiltrate and accelerate the process, especially in areas where it can freeze.

4 Insects are attracted to the increased number of producers and eventually move into the area. Drag the insects into the ecosystem The presence of insects helps to create soil. Use the brown highlighter to create a layer of soil below the moss. Soil is made of microscopic particles of minerals, decomposing organic matter, and pockets of air. The decaying bodies of dead insects, as well as the wastes they excreted while they were alive help to contribute to the creation of a layer of soil during primary succession.

5 Given time, other organisms will establish themselves in the area. In this case, the area was transformed into a forest. Place the following organisms into the ecosystem. Change their size as necessary. Climax Community The ecosystem is now a climax community, which produces the maximum amount of energy possible. The organisms here are best adapted to this ecosystem. If it is not disturbed, it may remain the same throughout time.

6 Primary succession can occur in different ways, and the end product can be any one of several ecosystems, but ultimately: Primary succession is the sum total of all the transformations from bare rock to climax community.

7 Secondary Succession Not all ecosystems are built on bare rock. Can you think of some natural phenomena that destroy ecosystems but don't return them to bare rock? Write them below:

8 Secondary Succession Secondary succession occurs when an ecosystem is built on the leftovers of a previous ecosystem. Fire, flood and violent storms are just some examples of natural phenomena that can destroy ecosystems. After such events there is still soil, minerals and organic debris, so the development of an ecosystem occurs much more quickly. Organic debris is the accumulation of matter that used to belong to living organisms. Most of it is the result of the natural breakdown of their bodies after they die (rotting matter). Climax Community In secondary succession, the climax community will look like the original community. It occurs on a surface where an ecosystem has previously existed.

9 Climax Community Irreversible Change Certain events can cause irreversible changes: - Mining - Pollution - Erosion, etc... When these events occur, human intervention is necessary and climatic communities become permanent.

10 Irreversible Change Discussion: Bright Ideas! Why do these events cause irreversible change? Can you think of any other events that might cause irreversible change?