What is ecological succession in Biology?
Species within biotic communities rise and fall in a remarkably orderly and predictable fashion through the process of ecological succession. The first plants to colonize an area are called pioneers; they pave the way for other species. The destiny of a species is intrinsically bound to environmental conditions. Succession is ongoing because dominant species can alter the environment in ways that optimize growing conditions for competitors. Succession also occurs after habitat destruction. A biome that achieves long-standing stability is considered a climax community.
Primary succession is the sequential establishment of ecosystems in barren areas previously devoid of soil or sediment, as explained by the authors of “Living in the Environment: Principles, Connections, and Solutions.” Over time, enough soil accumulates to support additional plant species, which provide food and shelter for birds and animals. Kenai Fjords National Park in Alaska is an example of an area where primary succession is occurring. Retreating glaciers leave behind bedrock that’s gradually eroded by moss and lichen, thereby creating soil for pioneer species, like fireweed and alders. Increasing biomass and soil depth supports deeper rooted cottonwoods and spruce.
When a natural habitat is disturbed by external activity – such as overgrazing or logging operations - secondary succession occurs. Seeds in the soil start growing, and many indigenous species slowly and gradually return. For example, an abandoned cornfield in the eastern United States will first be overrun by weeds, which are then succeeded by grasses, goldenrod, blackberries, sumac bushes and deciduous trees, as described by Ahmed H. Hussen, author of “Principles of Environmental Economics.”