Ecological succession

Ecological succession

1. Communities gradually change from one type to another. The sequence of change, from the inital colonisation of a new area to establishing a relatively stable community, is called ecological succession. There are two main types; primary and secondary. Ecological succession happens in stages called seres or seral stages; each stage has its own community of organisims, and can usually be identified by the plants it contains.

2. Primary succession; colonizing a new area. Primary succession take splaces in newly formed areas where no life has previously existed

3. The process of succession. Succession is a complex process driven by many factors acting simultaneously. In the early stages, abiotic factors are the most impotant in determining whcih organisms colonize a habitat. Only those organisms that can tolerate the hostile enviroment can establish themselves. These are called pioneer species. Pioneer species arrive haphazardly and those tolerant of hostile survive. They may change the habitat in ways that favour other species more. After the pioneer species have become established, biotic factors become increasingly important in the habitat. When the colonizers die, they enrich the soil, making the habitat less hostile and allowing other species to become established. As succession continues, the species diverisity of the community increases, and the food web of the ecosystem becomes more complex

   • According to the climax theory, ecological succession leads to a more complex community with a high species diversity that is in equlibrium with its enviroment. This has been called the climax community. It is generally assumed that an increase in species diveristy makes an ecosystem more stable because of the large number of alternative links between members of the community.

4. Secondary succession; takes place in the areas where life is already present but has been altered in some way. this process is faster than promary succession because the soil often contains seeds.

5. There are three main causes of primary succession; 1.Natural catastrophes that remove existing vegetation 2. Human destruction of climax communities 3. Human management of habitats to maintain communities at an early succession stage.

6. In order to prevent secondary succession occuring on and aerable land, the field would have to be ploughed regularly

7. Conservation biology and habitat management. Plagioclimaxes; a relatively stable climax community resulting from ecological succession that has been arrested, deflected, either directly or indirectly, as a result of human activity