Crown and root biomass equations for the small trees of Pinus koraiensis under canopy

Estimation of tree biomass is an essential part of studies on carbon sequestration and cycling in forest ecosystem.Small trees grow in the understory and allometric development is different from that of mature trees.However, less attention has been paid to biomass estimates of small trees, especially in mixed forest where tree competition is intensive.Tree allometric equations at both branch level and at whole tree level were, thus, developed and compared for the small trees of Korean pine (Pinus koraiensis) in a mixed stand in northeastern China.At branch level, the best model for live branch biomass was one which used a combination of branch diameter, branch length, whorl position and relative branch depth.For needle biomass, the best model did not significantly improve the estimate with more variables.At whole tree level, stem diameter at breast height (DBH) was a significant determinant of biomass for different components.Tree height did not significantly improve biomass estimation at all.Tree crown variables proved to be useful for estimating all biomass components except the fine roots.The variable measuring aboveground competition intensity was a significant negative determinant of biomass components except canopy biomass.Comparisons to published equations for the same species growing in Heilongjiang province in northeastern China and in central South Korea, were also presented.Both total aboveground biomass and belowground biomass in our study showed somewhat smaller values for a given diameter than the trees growing in other two places.