Agroecological regional ranking of the basic density of stem wood stock in coniferous tree species of Eurasia

Abstract

In studies of the carbon cycle and plant ecology, a useful indicator is the basic density of wood (BD) as the ratio of the mass in a dry condition (at 0% humidity) to the «green» volume (the volume of wood in a state of saturation with water). Data on the wood BD of most species within the region are often unavailable, and averages at the level of genera or families are used. However, there may be significant phylogenetic and geographical variability of BP, and the use of its average values at the genus level is possible only in the absence of regional data. Almost all published data contain information on the BP of the wood itself, excluding bark. If it is necessary to calculate the biomass of stems above bark according to the available volume data having in mind the BD, which differs for wood and bark, then it is impossible to obtain the desired result with sufficient accuracy, since in each specific case the ratios of wood and bark are unknown, and they are differ significantly. The presence of huge amounts of data on volume stocks accumulated by traditional forest taxation makes it possible to estimate the dry biomass of stems with the bark over large areas using known values of the stem BD. The purpose of our research was to analyze the regional features of stem wood BD of coniferous tree species of Eurasia. Using the author's database on the qualimetry of trees of forest-forming species of Eurasia, a sample of 3220 trees of five coniferous tree genera (subgenera) of Eurasia was formed. A mixed-type model structure is applied, including numerical (age and stem diameter) and dummy variables encoding geographical regions. Two rankings were performed according to the BD of stem above bark, namely, the ranking of clusters (regions) within the genus (for five-needed pines – within the subgenus) and a species-specific ranking, according to which the maximum values are characterized by Picea orientalis (L.) Link and the minimum ones by Picea jezoensis Siebold & Zucc. The obtained models and the ranking of species by the value of the BD of the stems above bark can be used to calculate the carbon pool in coniferous stands according to forest inventory data.