Influence of clear-cutting on ground vegetation biomass and dwarf shrubs increment in the Scots pine forests of the European North-East

Background: In spite of important functions the ground vegetation performs, the research on global change and human impact on forests has traditionally focused on tree layer. We have analyzed the influence of clear-cuttings on ground vegetation biomass (GVB), fractional structure and annual increment of dwarf shrubs (bilberry and cowberry) shoots. The investigation was carried out at clear-cut areas of the Scots pine forests in the European North-East of Russia. Results: The GVB value after clear-cutting increased by 1.9-2.4 times. The GVB values at particular technological elements of clear-cuts (apiaries, skidding tracks) were obtained. On skidding tracks, the biomass was by 1.2-1.7 time less than that on apiaries. Among individual species, Vaccinium vitis-idaea L., Pleurozium schreberi (Willd. ex Brid.) and Dicranum polysetum Sw. demonstrated a positive reaction to clear-cutting but mosses of the Sphagnum L. genus reacted negatively. Invasion of Epilobium angustifolium L. and Avenella flexuosa (L.) Drejer increased the grass biomass, especially on skidding tracks. The linear model was applied for describing the relationship between above-and underground dwarf shrub biomass. The clear-cutting had a negative effect on shoot age and mass of both bilberry and cowberry. However, comfortable light conditions raised the role of foliage in biomass and heightened the increments of studied dwarf shrubs by 1.2-1.3 time.Conclusion: Clear-cutting had a positive effect both on GVB and increment of dwarf shrubs in Scots pine forests on the European North-East.