Ecological Succession

Primary succession is the development of a community in an area where no living things previously existed. It begins in a place without soil. Primary succession follows events such as volcanic eruptions or retreating glaciers. Pioneer species like lichen that do not need soil to live begin primary succession. Over time, soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces. When lichen die, they decompose and add small amounts of organic matter to the rock to make soil. Simple plants like mosses and ferns can grown in the new soil. The simple plants die, adding more organic material to the soil. As the soil layer thickens, grasses, wildflowers, and other plants begin to take over. These plants die which adds more nutrients to the soil allowing shrubs and trees to survive. Now insects, birds, and mammals can move in and be supported. What was once bare rock now supports a variety of life.

Secondary succession is the reestablishment of an area of land with plants and animals after the previous community was destroyed or removed. It begins in a place that already has soil and proceeds much faster than primary succession. Secondary succession follows events such as forest fire or deforestation.