Study On Individual Tree And Standing Forest Growth Rate Models Of Pinus Massoniana Based On The Permanent Sample Plot

The growth rule of Pinus massoniana was discussed by choosing a lot of permanentsamples’ data in Guangxi forest resource continuous inventory, by using SPSS software forstatistical analysis and computing platform. Samples were divided into three regions includingthe entire district, the north district of Guangxi and the south district of Guangxi in accordancewith the characteristics of the natural geographical condition. Then, the growth rate model ofindividual tree and standing forest were respectively established on the basis of the samples, Inthe end, the main results were as follow:(1) The model were fitted and evaluated which was based on the five periods of sampleindividual tree’s data with angle gauge measuration, by the method of nonlinear weighted leastsquares regression estimation.Finally, It was concluded that the models were the best formulaDBH and volume growth rate model of Pinus massoniana.Then, three index of the residualstandard deviation, the average relative error and the system error were used for adaptabilitytest of the models. It turned out that the predictions were in the margine range. Therefore, thefitting model could be applied to future growth forecast.(2) The individual tree growth rate models of Pinus massoniana were predicted the futuregrowth of the felled trees which were not under the natural state, And it was recounted that thestand growth quantity of angle gauge under the natural state. Then, the best growth rate modelabout the average stand DBH and the average stand height rate model were respectively toscreen out by fitting and comparison with many more equations on this basis. Finally, thepredictions of the models could conform to the requirement of the production precision bytesting the model. So this research could make accurate forecast for the stand DBH and treeheight of Pinus massoniana in the research district.(3) The growth rate model of basal area and stand volume of Pinus massoniana werefitted by the technique to linearize of negative exponential function. In terms of choice of themodel factors, the forest stand factors including the stand age, the stand density index and theposition of quality index were taken into account. the modeling results had achieved goodprediction effects by examination. The research results indicated that the technique hadapplication value, and it could be used to predict the dynamic change of basal area and standvolume about Pinus massoniana.(4)When the growth rate model about the diameter at breast height, the volume, the heightwere fitted, the estimate method of nonlinear weighted least squares regression estimationwhich was taken the inverse square of model as the weight function was effectively eliminatedthe effect of heteroscedasticity in the growth rate model. The method was reliable in theoretical basis and had small error and high precision, It provided better value for plantgrowth rate model about various species factors which are fitted by the method.(5) The modeling results had achieved good effects by the reiteration data during the earlyperiod to late period in forest resource continuous investigation. It showed that the data of forestresource continuous investigation could reflect objectively and comprehensively the currentstate of the stand. It was demonstrated that regional modeling was more close to the growthchange of Pinus massoniana by the comparative analysis of modeling effect which wasrespectively taken the whole district as sample and taken partition regional sample as sample. Itwas clear that regional modeling was very necessary. The models could provide reliable basisfor predicting the dynamic changes of forest resources’ growth and the data update of the forestresources, It provided technical services for the sustainable development strategy of Guangxiforestry.