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Forest ecosystems play an essential role in climate stabilization, and the study of their capabilities in this aspect is of paramount importance. How climate changes affect the biomass of trees and stands in transcontinental gradients is unknown today? The objective of this study was (a) to verify the operation of the law of the limiting factor at the transcontinental level when modeling changes in the biomass of trees and stands of the genus Betula spp. of Eurasia in relation to geographically determined indicators of temperatures and precipitation, and (b) to show the possibility of using the constructed climate-conditioned models of tree and stand biomass in predicting temporal changes in tree and stand biomass based on the principle of space-for-time substitution. As a result of the implementation of the principles of the limiting factor and space-for-time substitution, a common pattern has been established on tree and stand levels: in sufficiently moisture-rich climatic zones, an increase in temperature by 1 °C with a constant amount of precipitation causes an increase in aboveground biomass, and in moisture-deficient zones, it decreases; in warm climatic zones, a decrease in precipitation by 100 mm at a constant average January temperature causes a decrease in aboveground biomass, and in cold climatic zones, it increases.

In recent years, as the ecological role of forests has grown to a global level, the need to analyze their biological productivity in terms of biogeography has increased. Such studies are carried out mainly on a regional scale at the levels of both single-trees and forest stands. Thanks to formed by the authors the database on the biomass of 1076 sample trees of the genus Betula sp. growing on the territory of Eurasia, the trans-Eurasian model of tree biomass is proposed for the first time. The model takes into account regional differences in the biomass structure of equal-sized trees, harmonized on the principle of additivity.

On the basis of the compiled database in a number of 413 sample plots with determinations of forest biomass of the genus Populus sp. on the territory of Eurasia from France to southern China and Japan statistically significant transcontinental decreasing of stem, above ground and total biomass as in the direction from northern temperate to subequatorial zonal belt and in the direction from the Atlantic and Pacific coasts to the continentality pole in Siberia is established. Unlike wood story, understory biomass in these directions has not decreased, and increasing. The root: shoot ratio increases in the range between northern temperate and subequatorial zonal belts from 15 to 32% and within the southern temperate zone it monotonically increases from 5% on the oceanic coasts to 40% near continentality pole. The ratio of understory to wood story biomass increases from 0.3 to 1.6% ranging from northern temperate to subequatorial zonal belt, and within the south temperate zone it monotonically increases from zero values near Atlantic and Pacificcoasts, approaching the level of 40% near the continentality pole. The results can be useful in the management of biosphere functions of forests, what is important when implementing activities on climate stabilization, as well as in the validation of the results of the simulations for assessing the carbon-depositing forest capacity.

For the main tree species in North America, Europe, and Japan, a number of thousands of allometric equations for single‐tree biomass estimation using mostly tree height and stem diameter at breast height are designed. An innovative airborne laser method of the forest canopy sensing allows to process online a number of morphological indices of trees, to combine them with the biomass allometric models, and to evaluate the forest carbon pools. The database of 28 wood and shrub species containing 2.4 thousand of definitions is compiled for the first time in the forests of Eurasia, and on its basis the allometric transcontinental models of fractional structure of biomass of two types and dual use are developed. The first of them include as regressors the tree height and crown diameter and are intended for airborne laser location, whereas the latter have a traditional appointment for terrestrial forest biomass taxation using tree height and stem diameter. It is found that the explanatory capacity of the first model in comparison with the second one for foliage, branches, and roots is lower, but this difference is not statistically significant. The same capacity for the stem and aboveground biomass is lower too but this difference is statistically significant. Both models are designed for two different methods of taxation and cannot replace one another. Summary for Managers: We develop an innovative airborne laser method of the forest canopy sensing to evaluate the forest carbon pools.We show this approach is highly reliable: in the most cases, there is more than 90% of tree biomass variability.Processing speed of laser location, incommensurable with the terrestrial mensuration, gives the possibility to assess the change of carbon pool of forests on some territory during its periodic overflights.The proposed information can be useful when implementing activities on climate stabilization, as well as in the validation of the simulation results when evaluating the carbon depositing capacity of forests. [ABSTRACT FROM AUTHOR]