PHYTOMASS STOCK AND STRUCTURE IN DERIVATIVE FOREST STAND OF CENTRAL SIBERIA.

Data characterizing biological productivity of wooden layer in dark coniferous forests secondary succession stands of southern taiga subzone of West Siberian continental sector have been given. Thus, the obtained data prove that ecosystems of the same age group which vary in type of root vegetation forming, developing under the similar vitality conditions (temperature, moisture and nutrition) form different organic matter stores in phytomass. The wooden layer phytomass of secondary birch stands accumulates almost twice of organic matter (138--239 t/ha), compared with native fir stands of non-replacement regeneration (85--128 t/ha). The main part of phytomass stores is concentrated in stem wood and its absolute meaning increases with age. In secondary birch stands its part changes from 67% in 60-year-old forest stand to 63% in 100-year-old over mature forest stand. In native 50- and 90-year-old spruce-fir phytocenosis stem part in phytomass total store increases from 48 to 54% and reaches 64% in the age of 170. [ABSTRACT FROM AUTHOR]