Biomass Allocation Patterns and Allometric Models of Populus Davidiana and Pinus Tabulaeformis Carr. in West of Shanxi Province

Populus davidiana and Pinus tabulaeformis Carr.are two important tree species in western Shanxi Province.Biomass of each component and above and below-ground biomass of Populus davidiana and Pinus tabulaeformis Carr.were obtained by harvesting 40 trees with various diameters at breast height(DBH),and furthermore,their allocation patterns were analyzed.Allometric models for each component(leaves,branch,stem,root,aboveground and the whole tree) of Populus davidiana and Pinus tabulaeformis Carr.were then developed based on independent variables including DBH,tree height(H),trees factor(D2H),average crown width(CW),and crown length(CL),and the best fitting models were identified.The results showed that relative proportions of leaves,branch,stem and root to the total tree biomass were 3.42%,11.23%,64.30% and 21.06% for Populus davidiana,and 13.44%,19.86%,47.52% and 19.18% for Pinus tabulaeformis Carr.,respectively.The ratio of aboveground biomass and belowground biomass were 3.32∶1 and 3.99∶1 for Populus davidiana and Pinus tabulaeformis Carr.,respectively.The two variables were correlated linearly for both Populus davidiana and Pinus tabulaeformis Carr.(p0.001).The best fitting models of two species were CAR models.The allometric models explained more than 92% of the variance in the data,biomass allometric models based on DBH explained more than 90%,while leaves biomass allometric model explained more than 83%.Tree height should not be used alone to predict the biomass of each component.Considering the variance explainability and the practical need,it can be concluded that DBH is a reliable predictor for estimating the biomass of each component for both Populus davidiana and Pinus tabulaeformis Carr..