Succession
Succession is the somewhat predictable and orderly changes in the composition or structure of an ecological community. There are two types of succession: primary and secondary succession. These two differ in specific ways. Primary succession occurs on land where there was no previous growth, and there is no substrate, or soil. Secondary succession occurs on land where there has been previous growth before, and the substrate is made up of the soil and the seed bank.
Primary Succession
This is an example of primary succession in the desert. A sandstorm has pushed sand into sand dunes, which are covering the existing land. The first things to settle the land is bacteria. The bacteria are known as pioneer species because they break down the land, and they create soil for future plants to grow in. The next things to come in are the perennial plants, like desert grasses. These plants pave the way for introductory trees. Introductory trees in the desert include desert shrubs which are spread by windblown seeds. After the introductory trees, secondary trees, like desert cacti and trees, come in. These plants are spread by animals.
Secondary succession
This is an example of secondary succession in the desert. This example's succession was caused by a flash flood. The flood was caused by too much rain water coming in to the dry ground. The flood caused the plant life to be taken away, but it left the soil intact.