Effect of Massive Forest Shelterbelts on Humus Content and Stock in Chernozems

Changes in the humus content of Haplic Chernozems (Clayic, Pachic) under the impact of oak–maple forest shelterbelt were studied at the soil-ecological monitoring polygon in Volgograd oblast. It is located in the Kozlovsk forest planted in 1896 on a plowed land. The following aspects of the impact of the forest shelterbelt on changes in the humus status of Haplic Chernozems (Pachic) were analyzed: spatial and time variability of soil properties and humus content, humus content and reserves in plowed and forest soils, and soil changes under the effect of old and middle-age forest belts. Spatial variability of soils was studied on two transects, which crossed the forest belt and adjacent agricultural lands. The method of retrospective monitoring was applied to analyze medium- and long-term variability of humus content. Data on its dynamics for a 125-year-long period were obtained on the basis of comparison with a buried soil and with the results of studies at experimental stations performed in the 1950s by the team of the V.V. Dokuchaev Soil Science Institute. Interrelated studies of typomorphic characteristics of soils under the forest belt and on agricultural lands included the assessment of humus content and reserves, particle-size and aggregate compositions, density, soil solution reaction, and the content of easily soluble salts and calcium carbonates. The features of spatial and time variability of humus content and reserves in Haplic Chernozems (Clayic, Pachic) under different types of land use were determined.