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.