Differentiation of Forest Vegetation after Clear-Cuttings in the Ural Montains

The purpose of this paper is to study dynamics patterns of the Ural (Russia) forest ecosystems to allow their biodiversity conservation in the context of anthropogenic impact. One of our objectives was to test the hypothesis that external factors cause splitting-up of natural forests and their replacement by a range of successional series. Our research was conducted in the Southern Ural Mountains. We studied differentiation of the forest vegetation after clear-cuttings in the most typical environments: on smooth slopes 1–2 degrees steep with deep soils, at 400–500 m above the sea level. Tree stand, understory, and grass layer were studied within a number of sampling plots (0.5 ha). To measure biomass of grass and shrub layer laid 10-15 subplots (0.5x0.5m) within each sampling area. The obtained data was used in Correspondence Analysis (CA). For numerical analysis we used R package vegan. We found that clear-cuttings in the Southern Ural Mountains cause profound transformation of the forest vegetation structure and in all the layers. Patterns of regeneration-age dynamics differ both in tree stand and herbaceous layer: within a single natural forest, a whole range of alternative successional series are formed – spruce, fir, birch, and aspen forests (short-term, long-term, and stable-term secondary), each having specific productivity of herbaceous layer. All the studied after-cutting forests (after-cutting (secondary) 50–70-year-old spruce and fir forests, short-term secondary birch forests (age of 5–100), long-term secondary birch forests (age of 20–100), and 8–110-year-old stable-term secondary aspen forests) differ from natural dark coniferous forests in the structure of herbaceous biomass and dynamic patterns. The differences between natural and after-cutting forests remain for over 100 years.