The Changes in Sod-Podzolic Soil in European Larch Forest Plantations over a Long Period

The research has been carried out in European larch forest plantations (Larix decidua Mill.) with the recording of changes in their silvicultural effect and the properties of sodpodzolic soil under the canopy of plantations over a period of more than 40 years. The aim of this work is to determine the nature of changes in the morphological and physicochemical properties of soils under the canopy of European larch forest plantations over a long period (45 years) in the conditions of the north-eastern Moscow Region. The research has covered 2 sample plots located in the B2 type of site conditions (simple fresh subor), which corresponds to fresh blueberry pine forests. The first sample plot (permanent sample plot 46) is located in an artificial plantation created in 1871 by planting. As for the second one (permanent sample plot B-2), it is located in forest plantations created in 1870 by sowing. Throughout the entire period of the research, the forest plantations have been growing according to the Ia quality class and have significantly increased the stock of stem wood. In forest plantations of the sample plot 46, the stock increased by 470 m3/ha (the current increase over 42 years of observation has equaled to 11.2 m3/ha per year), and in forest plantations of the sample plot B-2 – by 417 m3/ha (the current increase over 41 years of observations has equaled to 10.2 m3/ha per year). This indicates that there is currently no decay in the cultivated stands: they function successfully up to a century and a half old. Over 45 years, there have been changes in the morphological and physicochemical properties of the soil. A decrease in the content of the clay fraction has been established, especially in the upper part of the soil profile. The actual, exchange and hydrolytic acidity of the soil have increased as indicators of the ongoing process of podzolization. At the same time, the thicknesses of the forest floor and the humus content in the humus-eluvial layer have risen. The absorption capacity, the content of the exchange bases and the degree of saturation with the bases have increased, especially in the upper horizons of the soil, and the hydrolytic acidity has risen. In general, over a 45-year period, there has been no significant deterioration in the properties of sod-podzolic soils under the canopy of European larch forest plantations, and there are even trends of improvement in some indicators.