Question

In hydrarch succession, the reed swamp stage is present between

• A. phytoplankton and submerged stage
• B. free-floating stage and marsh meadow stage
• C. marsh meadow and forest stage
• D. submerged and free-floating stage

Answer 1

The correct option is B free-floating stage and marsh meadow stage

The sequence of communities in hydrarch succession are as follows:

1. Phytoplankton stage - Phytoplankton are the pioneeer species. The death of these organisms provide organic matter or humus to the bottom layer of soil.
   
2. Submerged stage - The water becomes shallower, and submerged rooted plants get established leading to accumulation of more organic matter.
   
3. Free-floating stage - The plants with roots and leaves floating on the surface occupy the area. The submerged plants die and decay to further contribute to humus formation. In this stage, the water becomes shallower in the periphery of the water body.
   
4. Reed swamp stage - The water continues to get shallower. It is now suitable for the emergence of amphibious plants like reed grasses. They also form humus and their tangles roots accumulate silt.
   
5. Shrub or marsh meadow stage - Shrubs are able to tolerate sunlight and water logged condition. They transpire large amounts of water while continuing to add humus to the soil layer.
   
6. Forest stage - This is the climax stage where the soil becomes suitable for development of trees. The forest can be coniferous, deciduous or temperate.