Research On Growth Model And Stand Reasonable Density Of Pinus Tabulaeformis Plantation In Luonan Area

In order to study the growth of pinus tabulaeformis plantation reasonable and suitable density in shaanxi Luonan area,according to the layout in Luonan survey data obtained in the standard,applying the forest measurement,statistics and forest management method,explores the pinus tabulaeformis plantation structure characteristics of the distribution of diameter of the diameter distribution model is studied,and use half peak width expression developed suitable for the rational management density table,provide the appropriate theoretical reference for the local forestry workers management measures.The specific results are as follows:（1）The results showed that the DBH distribution of pinus orientalis plantation was similar to the normal distribution,which was shown as a single-peak curve with positive deviation（right deviation）,and the DBH structure was relatively simple.The trees of steps from 6 to 12 accounted for a large number of trees in the whole stand,while the trees of path steps accounted for a large number,resulting in a small DBH of the whole stand.（2）When stand density different and site conditions are similar,stand density is not very significant influence on pinus tabulaeformis height,diameter of trees and the influence of individual volume is more significant,with the increase of density of the stand DBH and individual volume value,the smaller the diameter and volume growth speed is slow,the corresponding growth is low.On the contrary,the diameter and volume of standard wood of pinus tabulaefolius plantation are larger.When the site conditions similar and stand density are different,the influence on DBH,tree height and total volume growth is that the negative slope is greater than the positive slope,and the lower slope is greater than the upper slope at the same slope direction.（3）Using undistorted model,Gamma distribution model,Log-Normal model,Logistic model,Weibull model.The results show that the lognormal distribution model is the best model in this study,with the best fitting effect,which is better than the other 4distribution function models.The corresponding parameters were obtained by substituting the characteristic factors of stand,and then the diameter distribution of pinus plantation in Luonan county was predicted.After the chi-square test,it was considered that the overall diameter distribution of all plots met the parameter estimation equation of lognormal distribution.（4）According to the data of the surveyed plots,the regression relationship between crown width and DBH was fitted,The expression between crown width and DBH is C_D=-0.50669+0.79871*D^0.62976,The maximum density equation is obtained by using the overlap coefficient of canopy.The density manageability formula is used to calculate the manageability of randomly selected sampling sites,The reasonable density management interval of pinus tabulata plantation in the study area is calculated by using the half-peak width formula（0.52,0.94）.The density table of pinus tabulaeformis plantation suitable for the study area was compiled according to the calculated data,which can provide the basis for the work of the local tending forest.