Biomass structure of Pinus sylvestris and Betula pendula forest ecosystems in pollution gradient near copper plant on the Southern Ural

Abstract

In the gradient of pollution from the Karabash copper smelter in the Southern Urals (55° 29’ N, 60° 13’ E) in predominantly pure Scots pine and white birch stands, 12 and 34 sample plots are established, respectively, on which 42 and 56 model trees are taken, respectively, by stem diameter. The pollution gradient is expressed by the toxicity index suggested with a relative index of the content in the litter of three "technogenic" metals Cu, Pb и Fe. Regression analysis of the dependence of biomass and NPP of trees and stands from toxicity index is performed. There is a log-log-linear pattern of reduction of biomass and annual NPP of spruce-fir forest stands with increasing toxicity index in the direction to the source of pollution, but for the biomass of trees in the same gradient no consistent pattern is detected. The dry matter content (DMC) in all biomass components depends on the toxicity index and species at a statistically significant level: due to the increase in the toxicity index, it decreases in wood and bark, and increases in foliage and branches. At the same toxicity index, DMC in the branches and stem wood more in birch, but in the bark and foliage – in pine. In the wood and bark of a stem, this index is also related to the position in a stem: in the wood it decreases, and in the bark it increases in the direction from the bottom up