Scientific publications

Iron-metamorphic soils of normal moistening were studied in the middle taiga subzone of Karelia. The examined sites comprise arable land, hayfield, 15- and 75-year-old naturally reforested pine stands on former farmland, and 100-year-old pine forest as a control. The effects of different land use types on soil morphology and the main chemical and microbiological characteristics of the upper horizons were analyzed. The stocks of organic carbon (Corg) and microbial biomass carbon (Cmic) in 0–100-cm soil layer and the structure of carbon pools in these sites were studied. Characteristic of the soils of all sites are a uniform accumulative type of carbon distribution and similar values of C/N ratio (16–18). The soils display a low natural fertility and unfavorable agrochemical characteristics, which are considerably improvable by agricultural management. Arable land has the highest Corg (4.9%) and Ntot (0.3%) contents at a low bulk density and neutral pH. The soil under the young forest displays the highest Cmic content (419 mg C/kg); soils of arable land and hayfield, 209–211 mg C/kg; and that under mature forest stands, the minimum (144–175 mg C/kg). The stock of microbial biomass carbon in the 0–100-cm soil layer ranges from 76.5 to 132.4 g C/m2 in the studied land use types and the Cmic content in the forest litter amounts to 12.7–27.4 g C/m2. In the 0–100-cm layer, Corg stock is the maximum in arable land, amounting to 272 t C/ha, and decreases from hayfield to mature forest stand (98 to 39 t C/ha, respectively). The total ecosystem carbon stock is the maximum in arable land (275 t C/ha), which exceeds the stock in mature forest stands (206–221 t C/ha). The Corg stocks in young forest and hayfield are 105–115 t C/ha.