用树干3个部位的直径建立立木干曲线方程

Estimation of Stem Taper Curve from the Diameter Information at Three Locations on the Stem

通常根据１０分法测定树干各部位直径，用最小二乘法拟合三次多项式干曲线方程的参数。从数学的角度，只要知道树干任意３个部位的直径，就可以用最小二乘法或联立方程式求解干曲线参数。为探讨用树干哪３个部位直径拟合的干曲线最接近实际干曲线，文章以樟子松人工林为例，采用实测直径与计算直径相比较，选择高精度的方法，所得结果表明６种直径组合的精度良好，其中含胸径的３种组合是拟合立木干曲线的有效方法。

The stem taper curve used is 3 degree polynomials that is stated an effective equation The parameters of this equation are generally decided by the least squares methor from diameter measured values at several or many locations on the stem, but can be decided by the simultaneous equations or the least squares method in mathematical stand point if the diameter measured values on the optional locations can be obtained only three Then we studied about which locations on the actual stem to select as diameter measurement to find out more approximated stem taper curve to the actual stem taper curve from three diameter measured values We carried out the estimation of stem taper curve using only the diameter information at three locations from the sampling trees of Pinus sylvestris var mongolica As a result, it was suggested that the combinations of diameter information of six kinds is effective from the precision Moreover, it was suggested that three combinations included DBH are more effective than remaining three combinations from utility