Study On Growth And Yield Model And System Visualization Of Cunninghamia Lanceolata Plantation Based On Forest Vegetation Simulator (FVS)

In this study,Cunninghamia lanceolata plantation was the objective,FIA forest secourse investigation system was introduced to establish the eircle stand.Along with data from permenant plots and analytical trees taken from Jiangle state forest farm in Fujian Province,5 individual growth and yield including height-diameter model,crown model,DBH increment(in 5 years)model(including big tree and small tree),height increment(in 10 years)model(big tree)and volume model were built,bark factor was calculated as well.Stepwise regression was used to establish DBH increment model and height increment model,optimal equations of other models were selected according to Akaike information criterion,Bayesian information criterion and Log Likelihood value as well as determination coefficient,accuracy test was conducted afterwards.74 published domestic and abroad biomass models were surmarized,analytical stem data was used to fit the models.Independent variables,parameters and equation form on how to build the model were analyzed afterwards.In this aspect,conclusions were as follows:the precision of equations was increased with larger number of parameters in certain extent.When selecting independent variables,biological characterastie of tree growth should be taken into consideration,i.e.wood density was rarely selected as independent variable,however,it did help to increase model accuracy.VVhile models contained the same independent variables,the expression of dependent variables affected simplicity of the equations,for instance,biomass expressed in logarithmic form had better performance than biomass itself.The more complicated the equation form,the less independent variables and parameters were needed,but there should be a balance among form complexity,equation simplicity and accuracy.Optimal biomass model was selected based on the above criterion.According to the simulation results,transformation equation between biomass and stand volume was built,to predict the fiiture stand growth.Applicability of FVS system to Chinese fir plantation was discussed.These models were developed to support further steps of the localization of FVS system in southern part of China.