Biomass Allocation Patterns And Allometric Models Of Larix Gmelinii

Larix gmelinii is an important coniferous tree species in cold temperate zone. In this study, the above-and belowground biomass allocation patterns of Larix gmelinii were analyzed using the whole-tree harvesting method.At the branch level, allometric models for live branch and needle biomass were developed based on independent variables of the branches of the base10cm in diameter (D10)、 branch length (BL).At the root level, allometric models for coarse root biomass and fine root biomass were developed based on independent variables of the roots diameter of the base (Dr)、root length (BLr). At the whole tree level, independent variables including DBH was used to develop allometric models for biomass components. The best fitting models were identified by stepwise regression method. Including three classes, i.e.,15dominant,16intermediate,7suppressed trees that were classified using a relative diameter method. Hegyi competition index is determined using the competitive strength of trees.The whole tree biomass (both above-and below-ground) were measured in order to (1) based on the level of branches and roots level allometric equation.(2) develop allometric models for the three classes,(3) quantify the effect of classes on biomass allocation, and (4)quantify the effect of tree competition on biomass allocation.The results showed that (1) branch biomass, leaf biomass, stem biomass,stump biomass, root biomass accounted for the relative percentage of the whole tree biomass, respectively:9.67%,2.73%,68.86%,7.05%and11.68%.(2) Aboveground biomass and belowground biomass was significant linear correlation (P<0.001), the slope of the linear fit equation was0.31.(3) At branch level and root level, two variables in the allometric model fitting results are better than one variable. DBH-based univariate model, all components of the biomass model can explain more than73%, foliage biomass, could explain the amount of the fine root biomass is relatively low. Compared with the independent variable DBH, root length and root diameter of the base no increase in the accuracy of root equation.(4) The best predictor of the allometric models varied with biomass components. Diameter at crown base was the most reliable predictor for branch biomass and foliage biomass, whereas diameter at breast height (DBH) was the most simple and reliable predictor for the other biomass components.(5) The allometric models for belowground biomass components did not differ significantly among the classes (P>0.05). For a specific DBH, the dominant trees allocated more biomass to branch and foliage components, whereas the intermediate trees allocated more biomass to stem component than the dominant trees, and more biomass to aboveground component than the suppressed trees. The tree height of the suppressed and intermediate trees was significantly greater than the dominant trees for a given DBH. The proportions of all the components except for stump to the total biomass did not differ significantly (P>0.05) among the tree classes, sugges. We concluded that the differentiation of L. gmelinii trees mainly caused by different light regimes caused divergence in the size of biomass components, but the relative allocation pattern was conservative.(6) With increasing competition index, tree diameter and tree height are reduced. With increasing competition index, tree branch biomass, leaf biomass, stem biomass, coarse root biomass, fine root biomass, stump biomass, and the whole tree biomass decreased. Competition index has no effect on aboveground biomass and belowground biomass proportion.