Stages of Restoration of Components of Post-Agrogenic Pine Forest Ecosystems at the National Park “Smolensk Lakeland”

Abstract

Rural depopulation in Russia was accompanied by the abandonment of arable lands and natural reforestation. The aim of the work was to study soils and phytocenoses of six stages of pine forest restoration on rocks with coarse granulometric composition in the north-west of Smolensk region. The research was carried out at 18 key sites, characterizing 6 stages in triplicates. Under agrocenoses and one-year-old fallow lands we found agrozemes (Arenosols (Aric)) with a thick arable layer and a minimum abundance and biomass of macrofauna, represented mainly by phytophages and saprophages. At the 2nd stage of fallow meadows, grey-humus soils (Arenosols) and sod-podzols postagrogenic (Entic Podzols) were found with unchanged morphological properties in comparison with the first stage. Here, the biomass of macrofauna is maximal due to intensive invasion of open biotopes by insects. Young (up to 30 years old) pine forests grew on similar to the Stage 2 regraded soils. During 10 years of a forest growth, litter and protohumus regrading horizons were formed. In middle-aged (70–80 years old) pine forests on sod-podburs post-agrogenic regraded (Entic Podzols), signs of an eluvial process are manifested. Macrofauna is characterized by a decrease in the biomass of a litter population. In forests older than 80 years, decay of pine stands with the formation of complex spruce forests have begun. In soils, even lower boundary of old-fallow horizon disappears without podzolic horizon formation. Here, the maximum biomass of litter macrofauna is revealed. The final stage is shrubby (lingonberry)-green-moss pine forests older than 90 years growing on podzols (Albic Podzols) with remains of old-fallow horizon. Among macrofauna, litter macrofauna prevail in terms of a biomass, but the biomass is lower than in the previous stage. Due to the different degree of morphological manifestation of the alfegumus process, the fifth and sixth stages can be considered as variants of the development of post-agrogenic soils under pine forests.