Modeling the additive structure of stand biomass equations in climatic gradients of Eurasia

It has been established that in cold climatic zones any increase in rainfall leads to a corresponding decrease in biomass volume and in warm zones an increase in rainfall leads to an increase in biomass value. Furthermore, in water‐rich areas (900 millimeters [mm] per year), a rise in temperature causes an increase of biomass values, whereas in arid areas (300 mm per year) it causes reductions. These statements confirm previously recognized results that other researchers documented at both local and regional levels. For natural and planted tree stands, these patterns follow suit, but in absolute terms plantation biomass shows annual increases in total biomass, roots, stems, needles, and branches, of 16, 18, 11, 2, and 3%, respectively, compared to natural stands. The percentage of change in the structure of biomass is related to the ratio of the two climatic indices—temperature and rainfall. In particular, for the central part of European Russia, the Russian Far East, and northeastern China, which are characterized by mean annual temperatures in January of –10 degrees Celsius (°C) and mean annual precipitation of 500 mm, any temperature increase of 1°C at a constant level of precipitation increases biomass of stands aged 100 years in total biomass, roots, stems, needles, and branches, by 2.2, 1.8, 2.5, 0.36, and 2.3%, respectively, regardless of the origin of the stands. In the same regions and with pine stands of the same age, a precipitation increase of 100 mm at an unchanged mean temperature reduces total biomass, roots, stems, and needles by 5.8, 2.3, 6.5, and 0.3%, respectively, and increases branch biomass by 0.3%. The development of such models for the basic forest‐forming species grown in Eurasia will make it possible to predict changes in the biological productivity of the forest cover of Eurasia related to climate change.