The relationship between soil conditions and the number of spruce undergrowth in mature pine-spruce stands of the Gatchina district of the Leningrad region

The study was conducted in 2021-2024 in the North-West of Russia (Leningrad region, Gatchina district). The objects of the study were mature pine-spruce stands, with 6 to 8 units of pine and 1 to 3 units of European spruce (Pícea ábies), belonging to the Baltic-Belozersky taiga forest growth region of the Luga-Oredezh landscape in the Oredezh plateau area. Sample plots were laid out in forests that have not been affected by human economic activity for a long time. On 10 sample plots, 10x10 m squares were laid out, for which a continuous census of undergrowth was carried out, a geobotanical description of the living ground cover was made, soil pits were laid with subsequent agrochemical analysis of the upper horizons. Cartographic materials of parcel structure in 10x10 m squares allocated on the studied objects with marked trees of the main tree layer, undergrowth and underbrush have been compiled. The article reflects the distribution of spruce undergrowth by the main root parcels identified in pine-spruce forests. Agrochemical indicators have been determined: humus content, exchange and actual acidity indicators, degree of provision with mobile nitrogen. A correlation analysis of the relationship of agrochemical indicators with the number of spruce regeneration has been carried out, which showed their insignificant influence on the regeneration of European spruce, compared with the influence of plant elements. A significant influence of relief on the processes of natural regeneration by forming a moss layer has been revealed. The obtained results can be used for a more accurate assessment of the success of natural regeneration during forestry measures, for restoration and conservation of forests in the south of the Leningrad Region.

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