Sedge-Meadow Stage - Hydrarch
Favoured by an increasing amount of light, as the former occupants disappear, they gradually change the reed swamp into a sedge meadow. And now species of Cyperaceae and Gramineae such as Carex, Juncus, Cyperus and Eleocharis colonise the area. They form mat-like vegetation with the help of their much branched rhizomatous systems. All these react upon the habitat by binding water-carried and wind-borne soil, accumulating plant debris and transpiring enormous quantities of water.
There is much rapid loss of water, and sooner or later the mud is exposed to air. As a result nutrients like ammonia, sulphides become oxidised to nitrates and sulphates. Thus the conditions in the area gradually change from marshy to mesic, and the marshy vegetation shows a decline. Upto the end of sedge-meadow stage, the climate of the region has no control over the succession because the water content of soil is high, irrespective of rainfall and climate of the region. At the end of this stage, the soil becomes dry and its water content will henceforth be dependent upon rainfall and climate of the region. The plants which succeed the sedge-meadow stage are therefore controlled by the climate to a very large extent. In dry climates the next stage may be grassland or some other xeric climax but in more moist climates it is woodland.