Question

 Define ecological succession and define and discuss the differences and similarities between primary succession and secondary succession. Give examples of each kind of succession, and explain why succession (in general) occurs.

Answer 1

---> ecological succession is a Universal process of directional change in community composition, on an ecological Time Scale. It leads to the establishment of a stable climax community, and is marked as the end point of succession.

----> succession, where no community existed before is called primary succession. In primary succession ,the unoccupied terrestrial site is first colonized by a few pioneer species which are often microbes . An example of an area in which a community has never lived before , would be a new lava or rock from a volcano that makes a new island.

It is started by pioneer species . And begins with barren rock , worn down and colonized with pioneer species.

----> secondary succession occurs at the site from where and already developed community has been destroyed by some natural disturbances such as fire or flooding or by human activity and a series of communities subsequently develop at the site. For example; the forest destroyed by fire and excessive lumbering maybe reoccupied by herbs in the initial stages.

It is started by remaining species. And begins with established soil in which many different plants can grow.

----- > similarities in primary and secondary succession are- both occur at predictable rate and both start at a disturbance.

----> it occurs because of the changes in the physical environment and population of species. New species of plants displace existing plants because their seedlings are better able to become established in the change environment. and newly arriving species alter the physical conditions often in ways that enable other species to become established.