The author elaborates on the subject of the biomass accumulation and decomposition balance in forest communities. Forests at the climax phases are considered to be the most balanced in terms of the biomass of their components. The notions of “current woody debris” and “fallen deadwood” are defined, and the average indices of tree and stand condition in boreal spruce forests, as well as data on the stock, volumes and phytomass of the tree stands and woody debris in pristine spruce forests are specified. The article states that in pristine forests not affected by human impact the volumes of current woody debris and fallen deadwood vary significantly even among biogeocoenoses with similar development dynamics. These differences are caused not by endogenous but most likely by exogenous factors. There is minor variation in the ratios of fallen deadwood volume to the tree stand volume, and woody debris phytomass volume to tree stand phytomass volume, which are 33.5 ｱ 8.9 % on average. Presumably, those particular values for woody debris as related to the growing stock could serve as a tentative estimator of the contribution of these consorts to the overall biomass balance of pristine forest biogeocenoses. The author gives an example of grouping fallen deadwood into decomposition stages carried out in four sample plots representing forests of different taiga subzones. The amounts of C, CO2, H2O and Q (energy) deposited by the tree stand and released in the process of debris decomposition in the biogeocenoses under study were estimated.