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说一个林分每英亩断面积有100平方英尺时,可以设想这个数字存在着很大的正的量测误差。这一高估误差是量测仪器和换算表本身存在的偏差造成的结果,因为这些量测仪器和换算表是建立在树木横断面是园的假设之上的。这一误差有多大,能否消除呢?直径卷尺量测结果给出的断面积高估误差是累积的,不能低消的。树木越呈偏园,其误差越大。胡希等人(1972年)假设,两个直角轮尺量测值的几何平面值所产生的断面积估计值比直径卷尺所得的更接近于真实断面积。马特恩(Matern1972年)确定,高估主要是采用直径卷尺或轮尺而引起的。由于树木的树干横断面是不规则的,因此,假设圆(或椭圆)会因所
When we say that a forest has 100 square feet of area per acre, it is conceivable that there is a large positive measurement error in this figure. This overestimation error is the result of deviations in the measuring instruments and the conversion tables themselves, as these measuring instruments and conversion tables are based on the assumption that the tree cross-section is a garden. How big is this error, can it be eliminated? The overestimation error of the sectional area given by the measurement results of the diameter tape measure is cumulative and can not be reduced. The more trees are partial park, the greater the error. Huxi et al. (1972) assume that the estimated geometric cross-sectional area of the two rectangular gauge measurements is closer to the true cross-sectional area than the diameter tape measure. Mattern (Matern 1972) determined that overestimation was mainly caused by the use of diameter tape or calipers. Because the tree trunk cross-section is irregular, therefore, it is assumed that the circle (or ellipse)