Explain any five stages of hydrosere.
It includes the following stages:
(1) Phytoplankton stage: Succession on a pond starts with phytoplanktons. Members of this pioneer community include blue-green algae, green algae, diatoms etc. They make their own food and multiply quickly. Their death increases the amount of organic matter in the pond.
(2) Rooted submerged stage : Due to increased mineral elements and formation of soft mud on the bottom of pond it becomes suitable for the growth of rooted submerged plants like Ceratophyllum, Hydrilla etc. Death and decay of these plants make the pond more shallower and new habitat is created not suitable for submerged hydrophytes.
(3) Rooted floating stage: Plants like Nelumbo, Nymphaea start growing there. Their leaves float on the surface of water and roots are fixed at the bottom of pond. Growth of these plants for a very long period of time, their death and growth of some free-floating plants like Azolia, Lemna, Wolffia make the pond much more shallower. Accumulation of increased amount of organic matter at the bottom of pond creates habitat for the growth of next stage of succession.
(4) Reed swamp stage : Reed swamp stage is represented by amphibious plants. The roots of these plants remain under soil (bottom of pond) and other parts remain exposed to air. Vegetation present on the margins of the pond float to reach central area and also increases the amount of organic matter.
These plants are blown away by the wind to the central area where they get mixed with surrounding mud. It leads to the formation of many islands of vegetation in the pond.
(5) Forest stage: This is climax community which is rapidly invaded by trees. It remains in equilibrium with environment completing the succession.