Many podsol soils form underneath coniferous forests, the fact that pine trees are evergreen causes a very thin litter layer inhibiting the production of humus.
The community of decomposers in the litter layer also includes bacteria, amoeba, nematodes, rotifer, springtails, cryptostigmata, potworms, insect larvae, mollusks, oribatid mites, woodlice, and millipedes.
As reed beds age, they build up a considerable litter layer which eventually rises above the water level, and ultimately provides opportunities for scrub or woodland invasion.