The soil cover of black alder forests consists of Sod-Podzolic-Gley, P
eaty-Gley, and Humic-Gley soils. These soils have a pH near 6, a high
humus content (to 50-cm depth), and high exchangeable Al and Fe (by th
e Mehra-Jackson and Tamm extracts). The formation of these soils is in
fluenced by river water and silt deposition, leading to growth of the
soil upward and burial of upper horizons, which stimulates peat format
ion.