The Analysis Of Tree Density Factor Of Different Poplar Forest And The Development Of Volume Table

The production of Poplar plantation management is closely re lated to the plan density.In order to produce the full benefit of the plantation,the reasonable stand density is needed to achieve the optimum allocation.Volume table is commonly used in forestry investigation,it is the base table for forest inventory.The particularly important table in the poplar plantation in plains area is the volume table depends on stand density.The measured point data from laser scanning technology provides precise forestry,it is the essential data for this research to analysis the variation of mensuration factors in different kinds of density in poplar stands and establish the volume table.Based on the laser point data extracted from 4 density of poplar stands in north Jiangsu Province,there are two parts of the research: First,analysis the impact of 4 kinds of stand density?spacing in the rows and spacing between rows: 3 m * 8 m,5 m * 5 m,4.5 m * 8 m,6 m * 6 m?of diameter at breast height,tree height,stem form and the merchantable volume;Second,analysis the tree height,tree crown-volume model in single stand density?plant row spacing: 3 m * 5 m?based on the laser point data from terrestrial and airborne laser scanning.Finally,the volume table based on both tree height and tree crown is established.The researc h has the following conclusions:1?Significant difference was found within diameter at breast height in different stand density.With the increase of stand density,stand average diameter at breast height decrease gradually.All the diameter distribution curve in different stand density plots showed normal distribution,while the distribution curve of 5m * 5m stand density plots appeared significant kurtosis,3m * 8m?4.5m * 8m and 6m * 6m stand density plots appeared wide and flat distribution in the curve.In fitting the diameter distribution curve for difference stand density plots,the using Weibull distribution model to fit the curve was better than use the model of relative diameter method,especially in the 3m * 8m stand density plots which had the highest adjust the determination coefficient R²,above 0.99.2?Significant difference was found within tree height in 4 difference kinds of stand density plots.Tree height distribution in all kinds of stand density plots had obvious change law of the same structure,and presented an asymmetric mountain shape curve w hich was close to the average tree height in each stand density plots.In general,forest tree height increased with the decrease of stand density,and the trend of increasing was slowly.Weibull distribution was the better model in fitting all four different stand density tree structure of height,of which the height in 6 m * 6 m stand density plots had the best fitting effect,with adjust the determination coefficient R² above 0.99.The reasons was that the number of trees in tree height distribution was relatively concentrated in 6m * 6m stand density plots,the tree height curve distribution was concentrated within 22 cm ? 28 cm.3?Significant difference was found within form factors and form quotient.With the decreased of stand density,form factors a nd form quotient decreased,the taperingness of the tree trunk increased.In the stand number density is similar to that of the stand density under different planting methods.The form factor and form quotient under stand density of 5m * 5m are larger than those of 3m * 8m,and 6m * 6m are larger than those of 4.5m * 8m.The 5m * 5m and 6m * 6m stand density stem form more full.The improve volume model for each different stand density plots are as follow:6m * 6m stand density plots: V=a₀g_1.3H+a₁g_H/2H+(a₂g_1.3)/a₂,3m *8 m ? 5m * 5m and 4.5m * 8m stand density plots,the common model is:V=a₀q₂g_1.3H+(a₂g_1.3)/a₂,with all different a₀?a₁?a₂.RMSE for 6m * 6m stand density plots is 0.014,accuracy is 97.4%,which is the best model within all the different stand density plots.The improve volume model for all different stand density plots is:V=0.539q₂g_1.3H+(1.299g_1.32)/q₂ the RMSE is 0.024 and the accuracy is 96.2%,which is lower than the model of each different stand density plots.4?The lower stand density was,the higher merchantable volume will be.The proportion of large timber was major in the lower stand density plots,therein,6 m * 6 m stand density plots had the highest proportion,46.50% in peak.5 m *5 m stand density plots had the highest rate of middle diameter timber,is 51.08%.3 m * 8 m stand density plots had the highest rate of small diameter timber,is 56.93%.5?The best diameter model for 3 m * 5 m stand density plots is V=a₀(e^{a₁+a₂H+a₃CW}),it was established based on the point cloud data from terrestrial and airborne laser scanning,with adjust the determination coefficient R² above 0.82 and the test of homogeneity of variance F is 454.3.The inversion model for diameter at breast height was established using tree height?H?and tree crown?CW?,which present a method for using airborne laser scanning to calculate the volume.According to the standard volume table in Jiangsu Province,the improved model was established: V=a₀(e^{a₁+a₂H+a₃CW})^a₄H^a₅,which has average relative error 4.84%.Finally,the standard volume table for 3 m * 5 m stand density plots was compiled.