Study On Above-ground Biomass Models And Carbon Content Factors Of Natrral Spruce In North-western China

In this study,based on the data of 150 sampling trees of natural spruce in three provinces(autonomous regions)of Gansu,Qinghai and Xinjiang,the biomass models for each components were fitted by using the DBH(D)、tree height(H)、crown width(Cw)、erown length(Cl)and their various combinations as independent variables,and then selected the best one.On the basis of the best models,the compatible tree volume and above-ground biomass equations were established.Then focusing on the incompatible problem between the sum of the independent models of each component and the total above-ground biomass,nonlinear measurement error method and two approaches,controlling directly under total above-ground biomass and controlling jointly from level to level,were used to design the compatible system for the total above-ground biomass and the biomass of four components(stem,bark,branch and foliage),and the total-ground biomass could be estimated independently or estimated simultaneously in the system.Finally,the components’ carbon content factors were analyzed.The results shows that:(1)The fitting results of biomass models with different independent variables shows that the best models for above-ground biomass,trunk biomass,crown biomass,stem biomass,foliage biomass and bark biomass were in the form of W=aDbHc,while for branch biomass the best model form was W=aDbCwc,.(2)In the case of the compatible tree volume and above-ground biomass equations,the prediction effects of the volume equations could be improved significantly when tree height was included as predictor,while it was not significant in biomass estimation.(3)For the compatible systems of above-ground biomass and sub biomass,two approaches,controlling directly under total above-ground biomass and controlling jointly from level to level,both were effective solutions to the incompatibility between above-ground biomass and sub biomass models,and showed the similar fitting effects.The comparison of independent estimate and joint estimate showed that,for the one-variable model,independent estimate method was better than joint estimate,but the multivariate models of two methods showed the same effective.(4)Comparing the imitative effects of the one-variable and multivariate compatible biomass models,the results showed that the fitting index of branch and foliage biomass models could be significantly improved with the increasing of explainable variables,but it didn’t have much effects on other components.(5)By analyzing various organs’ CCF of Picea spp.,it showed that there were no signifieant differences in the CCF between:stem and bark,stem and branch,stem and foliage,bark and branch,but there were significant differences between:bark and foliage,branch and foliage.The order by average CCF from the largest to the smallest is foliage,stem,root,branch,and bark.The CCF of trunk showed a gradual increasing from top to bottom,but the differences among the upper、middle and the bottom were not significant.As for the roots,it was showed that the difiference was significant between rhizome and thick roots,whereas the CCF’s of thick roots and fine roots,the rhizome and fine roots were not significantly different.