|Class 12 Biology Ecosystem||Ecological succession|
The gradual and fairly predictable change in the species composition of a given area is called ecological succession.
The changes lead finally to a community that is in near equilibrium with the environment and that is called a climax community.
During succession some species colonise an area and their populations become more numerous, whereas populations of other species decline and even disappear.
The entire sequence of communities that successively change in a given area are called sere(s).
The individual transitional communities are called seral stages.
Ecological succession is of two types-
Succession that starts where no living organisms are there or these could be areas where no living organisms ever existed.
Primary succession can occur in newly cooled lava, bare rock, newly created pond or reservoir.
Succession that starts in areas where all the living organisms somehow lost that existed there is called secondary succession.
Secondary succession can occur in abandoned farm lands, burned or cut forests, lands that have been flooded.
Secondary succession is faster than primary succession because some soil or sediment is present.
Fig. bare rock, cooled lava, cut forest