SPRUCE FORESTS DISTRIBUTION BY THEIR VITAL RESISTANCE IN THE MOUNTAIN FORESTS OF NORTH TYAN-SHAN
The most important component of North Tyan-Shan mountain forests is the unexplored endemic Shrenka spruce variety (Picea sehrenkiana Fisch.et Mey). Its plantations play an important role in the regulation and redistribution of the surface runoff, maintenance of soil surface layer and protection from the destroying mud streams, as well as in the formation of the optimal esthetic and recreation environment. The nature of territorial distribution of North Tyan-Shan spruce forests located on the hillsides of northern exposition by the vitality grades has been studied. There were identified five grades distinguished by the trees condition: 1 - without any signs of weakening, II - weakened trees, III - highly weakened ones, IV - drying trees, V - dead standing trees. High changeability of taxation indices of the Shrenk spruce plantations of different age has been ascertained. It is shown that optimal conditions for carrying out the forest renewal measures are to be created in order the new generations of the above spruce would appear.