Question

What is succession? Discuss succession in ponds.

Answer 1

Ecological succession is a sequence of seres from baren land to the climax. In ecological terms, the developmental stages of a community are known as seral stages and the final stage as the climax community. The initial community of the area which is replaced in time by a sequence of succeeding communities until the climax is reached is called pioneer stage or pioneer community. The entire series of communities that is a characteristic of given site is called a sere.

Succession in ponds:

The hydrach succession or hydrosere succession is a succession in which a pond and its community are converted into a land community. Various stages of hydrosere are:

1. Plankton stage- It is the pioneer stage of hydrosere. Different spores reach the water body through wind or animals. The first organisms appear are minute autotrophs called phytoplanktons e.g. diatoms, green flagellates or filamentous green algae. Death and decomposition of these planktons produce organic matter. The latter mixed up with clay and silt at the bottom to form soft mud favourable for the growth of next seral stage.

2. Submerged stage- The bottom lined by soft mud having organic matter is favourable for the growth of submerged plants like Hydrilla, Vallisneria etc. They are rooted in the mud and form dense growth. As a result, sand and silt and humus get deposited around the plants. This enriches the newly built up bottom and makes it favourable for the growth of next stage.

3. Floating stage- Floating leave anchored plants appear when water is shallow. The plants make the water rich in mineral and organic matter. It becomes suitable for the growth of free-floating like Wolffia, Azolla etc. They cover the surface of water quickly.

4. Reed swamp stage- Amphibious plants grow where the water body becomes shallow. The plants of swamp stage transpire huge quantities of water. They also produce abundant organic matter. Their tangled growth accumulates silt.

5. Sedge or Marsh meadow stage- The shores built up by Reed swamp stage are invaded by grasses and herbs. The plants transpire rapidly and add abundant humus. Therefore soil is build up to invite the next stage.

6. Woodland stage- The periphery of sedge meadow stage is invaded by some rhizome which bears shrubby plants, which can tolerate bright sunlight as well as waterlogged conditions e.g. bogwood. The shrubs shade away from the plants of sedge meadow stage and they invite invasion by trees capable of bearing sunlight and waterlogging. The plants of woodland stage lower the water table by transpiration and built up more soil. Shade-loving plants grow below them.