The Growth Models Construction And Environmental Impact Analysis Of Pinus Yunnanensis In Yunnan, China

Pinus yunnanensis is one of the main timber species in Southwest China and plays an important ecological function,economic and social benefits.The study of the growth model of Pinus yunnanensis can provide the theoretical basis for the sustainable management of Pinus yunnanensis stand in the future.The reference provided for quantitatively describing the dynamic change of Pinus yunnanensis stand under the global climate warming by the study of the main environmental factors that influence Pinus yunnanensis stand growth and quantitatively analysis the environmental response mechanism of stand growth.The study was carried out in the following 4 aspects based on the Continuous Forest Inventories?CFI?in Yunnan Province.Analyzed the forest structure characteristics of Pinus yunnanensis stand,established the single tree growth models and the stand growth models of Pinus yunnanensis in central Yunnan,the environment interpretation of the growth models'parameters and analyzed the effect of environmental factors on the growth of Pinus yunnanensis stand in central Yunnan Province in order to provide a reference for the study on the growth model of Pinus yunnanensis stand in the future.The main conclusions were as follows:?1?The diameter distribution curve of Pinus yunnanensis stand deviated to the left with a low peak distribution.The determination coefficient of the five types of stand diameter cumulative structure models were all above 0.94.The number samples of Pinus yunnanensis showed unimodality that increased firstly and then decreased with the increase of the height increasing.The number of trees per hectare in Pinus yunnanensis forest is about 1100/hm².The diameter volume of Pinus yunnanensis forest showed a single peak change with the increase of diameter.The average volume of Pinus yunnanensis forest increased with the increase of DBH.?2?The determination coefficients of the growth model of single tree DBH,volume and basal area of breast-height of Pinus yunnanensis were 0.832,0.907 and 0.880,and the predict precision were 0.832%,0.907%and 0.880%.The model fitting effect is better and has certain applicability.?3?Seven basic theoretical growth models were used to fit the stand average DBH,average height and standing stock.The optimal models were Gompertz model,Logistic model and Richards model.The fitting coefficients were 0.648,0.618 and 0.232,and the predict precision were 96.53%,95.14%and 87.82%.The model fitting effect is better and has certain applicability.?4?The degree of influence of environmental factors on the growth model of stand average DBH was ranked as follows:SCI>HI>ALT>MAP>ET₀>MAT>WI>CD>BT>WS>SLO.The degree of influence of environmental factors on the growth model of stand average height was ranked as follows:SCI>HI>MAP>ALT>ET₀>WS>MAT>WI>CD>SLO>ST>BT.The degree of influence of environmental factors on the growth model of stand standing stock was ranked as follows:CD>SCI>ET₀>WS>MAHR>SLO>MAT>BT>HI>MASD>WI>MAP>ST.?5?ALT,MAT,SCI,MAP,HI and ET₀ affected the maximum of average DBH growth.SLO,CD,BT,WI and WS affected the maximum and growth rate of average DBH growth.MAT,SCI and MAP affected the maximum of average height growth.SLO,ST,CD,ET₀ and HI affected the maximum and growth rate of average height growth.ALT,BT and WI had little effect on the average height of the stand.SCI,MAT,MASD,BT and HI affected the maximum of stand standing stock growth.SLO,CD,MAHR and ET₀ affected the maximum and growth rate of stand standing stock growth.ST,MAP and WS affected the growth rate of stand standing stock growth.?6?Analyze the comprehensive effects of environmental factors on average DBH,mean height and stand standing stock by using the stepwise regression method.The fitting coefficient of the optimal estimation model of stand average DBH,average tree height and live stocking were 0.774,0.924 and 0.670.The predict precision were all above 91%,and the model fitting effect was good with certain applicability.