Density of Tree Wood and Bark in Climatic Gradients of Eurasia

Under the conditions of climate changing, the biospheric role of forest cover is increasing, as is the relevance of research into the carbon depositing capacity of the world’s forests. These studies include an assessment of the biological productivity of trees and stands, which includes not only phytomass, but also the basic density (BD) of stem wood and bark. In our study, allometric models of the BD of wood and bark of nine forest-forming tree species of Northern Eurasia have been developed, including independent variables such as the tree age and stem diameter, as well as the average temperature of January and average annual precipitation. The structure of a mixed-effects model is applied in which the affiliation of the source data to each of the tree species is encoded by a set of dummy variables. Based on the space-for-time substitution principle, the obtained patterns of BD changes in spatial climatic gradients are used to predict their changes in temporal gradients. The effect of Liebig’s law of limiting factor in predicting BD in spatial and temporal climatic gradients has been confirmed. The revealed patterns of changes in the BD of wood and bark in temperature and precipitation gradients completely repeat the previously established patterns of changes in phytomass and net primary production of trees and stands of Eurasia in the same gradients. This means that the climatic conditionality of the studied indicators of biological productivity has a common nature for both quantitative and qualitative indicators of trees and stands.