BIODIVERSITY MONITORING AFTER NATURAL AND ANTHROPOGENIC «CATASTROPHES» IN SPRUCE FORESTS OF THE EUROPEAN PART OF RUSSIA

We analyzed the main trends of the change in the species richness of plant communities after catastrophic natural (catastrophicwindthrow, fires, large bark beetle outbreaks) and anthropogenic (clear felling) disturbances. The main factor determining the increase in species richness was the intensity of ecosystem disturbance after ca- tastrophes. The greatest disturbance was caused by clear-cut logging, when all timber was removed from the felling area by tractors. Fires also could totally destroy stands and all components of the forest ecosystem. Large- scale wind damage affected only the trees of the upper layer, while all other components of the plant communities were slightly damaged. The bark beetle outbreaks cause the death only of upper layer spruce trees, while the whole forest ecosystem remains unchanged. The degree of disturbance of stands, undergrowth, herb-dwarf scrubs layer, moss cover, litter and soil during the dieback of spruce forests as a result of ‘catastrophes’ determines the degree of vegetation recovery in disturbed areas. We studied the spruce forest in the zone of coniferous-broadleaved forests of the Moscow region, affected by an outbreak of typograph bark beetle.Dynamics of understory plant species richness was fundamentally different after stand salvage logging following beetle outbreaks and in unlogged standswith preserved deadwood. Monitor- ing observations of plant communities during 10 years on permanent sample plots revealed the main feature of the plant species succession after clear felling. For the first six years succession passed through the herb and the shrub stages with a sharp increase in species and structural diversity of plant communities. Only in the forest stage the species composition characteristic of the forest was restored. In the deadwood stand the forest communities was preserved and no differences in the dynamics of species richness of the original undisturbed forest were detected. Only dominance of species in the stand and herb-shrub layer changed. If man don't clear cut dead and wind- damaged areas of spruce forests, it will result in development of mixed forests with increased resistance to pests and forest diseases. Monocultures of spruce forests may be replaced by mixed forests, increasing the diversity of forests.