Question

What is ecological succession. Mention its different steps. Explain Hydrach and Xerarch succession with diagramatic representation.

Answer 1

The process of change in ecological community of an area over time which in turn results in the formation of climax community is termed as succession. Ecological succession is the directional change in the flora and fauna of a given region over a period of time. It is the process of gradual change in the species structure of an ecological community over time.

There are three different steps as primary and secondary succession.

1) Primary (pioneer) succession is initiated when a new area that has never previously supported an ecological community is colonized by plants and animals. This could be on newly exposed rock surfaces from landslides or lava flows.

2) Secondary (intermediate) succession occurs when an area that has previously had an ecological community is so disturbed or changed that the original community was destroyed, and a new community moves in. This is more common than primary succession and is often the result of natural disasters such as fires, floods and winds, as well as human interference such as logging and clear cutting.

3) The last stage is considered as the climax stage when the population comes to a stable stage.

Hydrarch is a plant succession which starts in relatively shallow water, such as ponds and lakes and culminating in a mature forest, e.g. phytoplankton, Hydrilla, Vallisneria. Hydrarch succession takes place in wetter areas and the successional series progress from hydric to the mesic conditions. Xerarch is a plant succession starting on bare ground or rock and culminating in a mature climax forest. The pioneer species, such as lichens and mosses, result in the gradual accumulation of soil. Xerarch succession takes place in dry areas and the series progress from xeric to mesic conditions. In ecology, a mesic habitat is a type of habitat with a moderate or well-balanced supply of moisture.