Question

what is meant by term ecological succession?? provide details regarding ecological succession on land and water.

Answer 1

Whenever there is a bare land (or previously occupied land which is not currently in use) plants and animals colonize this land where simpler organisms are replaced by more complex organisms with changing environmental conditions and time. This process is known as ecological succession.

Ecological succession on land
The succession initiated on bare rock or wind blown sand where water is low is termed as xerarch. The first plants to colonize here are crustose lichens like Rhizocarpon, Rhinodina and Lecidea. Foliose lichens (Dermatocarpon and Parmelia) replaces the crustose lichens which in turn are replaced by mosses like Polytrichum, Tortula etc. After mosses herbs occupy the land which is replaced by shrubs like Rhus and Phytocarpus. Finally the climax species i.e. forests becomes dominant in the land.


Ecological succession on water

Succession occurring on water starts with phytoplanktons which colonize the nutrient poor water. Submerged hydrophytes like Hydrilla, Potamogeton and Vallisneria replaces the phtoplanktons. After submerged hydrophytes comes the rooted plants which have their leaves floating on water surface like Nymphaea, Trapa and Monochoria. Next stage in succession on water is amphibian stage dominated by plants whose shoots are exposed to air like Typha, Sagittaria etc. Then comes sedge-meadow stage defined by Juncus, Cyperus and Eleocharis. After this certain species of shrubs and trees appear followed by the forests.