Studies On Standing Tree Biomass Models And The Corresponding Parameter Estimation

As an important research item of ecology,the biomass is receiving more andmore attention because of its important environmental overloading functionespecially with the problem of environment becoming more and more prominent.As a main body of land ecosystem,forests produce more than 90 percent of thetotal biomass of land ecosystem and then the research on forest biomass becomesthe kernel of research on land ecosystem biomass.So,carrying out research onforest biomass would be of much importance on research on land ecosystembiomass.Meanwhile,forest tree biomass consists of the fundamental of researchon forest ecosystem biomass.To date,there are still several problems on researchon forest tree biomass to be solved at home as belows:(1)past research on forest single tree biomass is limited at local position,that is,in a small-scale level and then lack of a large-scale level such as a nationallevel.(2)past research is mainly on plantations and a few tree species.(3)the total tree biomass model is incompatible with its component biomassmodels(4)the biomass table for some tree specie is not widely applicable in space andtime. To aim at solving these problems,this thesis carried out some research as belows:1 Analyses of 796 samples of each component of 67 objective sample trees for8 species showed that,(1)the total tendency of variation in dry matter ratio andbasic density of each component of each specie followed that the dry matter ratioof stem and crown at different position,that is the upper,middle,and lowerposition of stem and branch is of difference while the basic density of stem atupper,middle,and lower position is of no significant difference.(2)the drymatter ratio and basic density of each component of tree could be estimated bymodel y=bx+ε,that is,(3)the dry weight of stem is calculatedby weighted method because of the different proportion of tree volume andweight at upper,middle,and lower position.2 Validation on Larix olgensis showed that the error of tree biomass model isheteroscedastic.Thus,a parameter estimate method where the heteroscedasticityis overcome by the model itself as weight function was proposed.Furthercomparison of CAR model with VAR model showed that the CAR model wouldgive more stable parameter estimate and more accurate estimation than the VARmodel.3the biomass model of each component compatible with volume model wasconstructed from the point of view of compatibility of biomass model and volumemodel.That is,to introduce volume factor into the CAR model is not only tomake the biomass and volume compatible but also to inherit some charactersfrom CAR model and give more accurate estimate of biomass.4Based on the compatibility of models, the independent model of eachcomponent of biomass,and the algebraic relationship between each component offorest tree,the compatible models of each component of tree were constructed asbelows:...