Study On The Stand Growth Model Of Masson Pine Based On Thiessen Polygon Method

Pinus massoniana as common timber species in Guizhou,widely distributed in the whole province,the growth of pinus massoniana stand to make use of voronoi space analysis,on the basis of the growth equations of the six theory or experience,combined with the site conditions to build pinus massoniana stand diameter at breast height,tree height,volume growth model of multiple regression dummy variable to explore the potential growth of pinus massoniana space(Thiessen polygon area,S_T or point density,?or sample number,N)and site conditions(site quality level)of pinus massoniana stand average diameter at breast height(Dg),average tree height(H),the influence law of stand volume(M)growth,The growth status of Pinus massoniana under different site conditions was evaluated to provide theoretical support for continuously improving the resource benefits of Pinus massoniana plantation in Guizhou Province,giving full play to the multi-function of the forest and realizing sustainable forest management.The results showed that the Dg,H and M of Pinus massoniana stand were related to the area of Thiessen polygon,and the correlation index of Thiessen polygon area could be used as the independent variable of the growth model of Pinus massoniana stand.Among the basic models,the Logistic equation was the best fit for the Dg of Pinus massoniana stand,the Gompertz equation was the best fit for the H,and the Schumacher equation was the best fit for the M.Compared with the basic model,the relative index(R~2)and the prediction accuracy(P)of the optimal dumb variable model with Dg,H and M were significantly increased,and the mean relative error(MPE),residual mean square(MSE)were significantly decreased.The constructed growth model has certain biological significance and applicability.Based on the theoretical or empirical growth equation,the Dg,H and M growth models of Pinus massoniana stand with Thiessen polygon area and site quality grade as the dummy variables have good fitting effects,with the R~2above 0.80 and the P above 95%,which are suitable for reflecting the growth law of Pinus massoniana stand in Guizhou Province.In addition,Thiessen polygon method also provides a new way for the establishment of growth models of other tree species.