The abiotic environment of wetlands is
dominated by the position of the water table
relative to the substrate, and whether waterlogging or flooding is a permanent or a
seasonal feature.
The water table, in turn, determines the
concentration of oxygen in the soil.
Whereas well drained soil contains many air spaces, these are filled with water in
flooded soil. Furthermore, decomposition of organic matter in the soil by microbial
action rapidly depletes oxygen. The rate of diffusion of oxygen through water is
10000 times slower than its rate through air, so the rate at which oxygen is used in
respiration easily outstrips the rate at which it can be replaced.
Absence of oxygen is, in itself, a problem
which wetland organisms need to
overcome, but it also has implications for soil chemistry.
