Study On Crown-shape Mode Of Main Coniferous Species In Heilongjiang Province

The shape of the crown is not lineal changing and the radius of the crown is not simply increasing as the depth of the crown as well. In this thesis, the red pine, larch and spruce-fir in different ages, densities and site conditions in Mengjiagang tree farm and the Forestry Bureau of Muling county are taken as research objects, and based on the analytical data of the branches of the131sample trees of the35study plots, the crown-shape database of various tree species is established. According to the analysis of the data of relative crown-shape of various tree species and the previous research results, it is found that the crown-shape of the coniferous species is not lineal changing, the radius of the crown reaches to the maximum at the lower part, while at the top and the bottom of the crown, the radius is zero, thus its crown-shape curve should be a curve with an inflection point. For this characteristic, a continuous piecewise function with an inflection point parameters model is established in this thesis to simulate the curve of the crown-shape. And by using the SAS9.1statistical software, the optional models of various species are respectively fitted and the results are analyzed and compared to get that the crown-shape models of all species are piecewise parabolic function model whose result of parameter estimations are good and fitting precision and prediction accuracy are both high. The model established in the thesis can be used to reasonably describe the crown-shape and variations of red pine, larch and spruce-fir.The crown volume are calculated through rotation quadrature by using the best fitting effect of piecewise parabolic model. Based on the crown-shape data of every sample tree, the curvilinear equation of the crown shape of individual tree of every specie is respectively fitted and the corresponding accumulate points are calculated. Then the individual crown volume comes out, which is compared with standard value to calculate the relative error which is used as estimation standard to calculate volume. The result shows that most relative error of red pine are distributed at the level of5%-10%, while the relative errors of larch and spruce-fir are concentrated below10%. Hence, the crown volume calculated via piecewise parabolic model has relatively higher accuracy and reliability, which also demonstrate that the piecewise parabolic model established in this thesis could be used to accurately fit crown-shape to a great extent.