人工林造林密度样圆调查圆心点位设置研究

Center setting of circular plot in the investigation of plantation density

林分密度是短轮伐期工业原料林经营的关键指标之一。为了满足当前人工林生产中林分调查的需要,采用计算机模拟的方法,从理论上研究了不同圆心点位对人工林造林密度样圆调查误差的影响。结果表明:①相同株行距不同坐标为圆心点的样圆内株数并不完全相同,存在明显的变动。相同造林密度,株行距不同时,同一圆心点位对应的样圆内的株数也不完全相同。②在同一株行距的总体中,采用24个随机起点为圆心点的样圆求算人工林株数密度调查的平均值,能代表实际情况。③对于设计株行距为1.50 m×4.00 m,2.00 m×3.75 m的样圆的最优圆心点位为某一株树(种植点),坐标是(0,0)m。④株行距为2.00 m×3.00 m时,样圆的最优圆心点位坐标为(1.5,0)m。⑤在造林株行距为1.20 m×5.00 m时,样圆的最优圆心点位坐标为(0,1.0)m。⑥在造林株行距为2.00 m×4.00 m时,圆心点最佳点位为相邻两行中间,坐标为(0,2.0)m。

Plantation density is one of the key indices in the management of short-rotation industry material plantation. In order to meet the requirements of investigation on plantation stands, we employed the method of computer-aided simulation, and studied the effects of different centers of circle on the error in the circular investigation of plantation density. Results show that： 1 ） the number of individual trees differs in sample circles with the same spacing and different coordinates, with an evident variation. For the plantation with the same density, the number of trees in the sample circle with the same center also changes under different spacing. 2） in the situation with the same spacing, the mean value of plantation density, using 24 random points as centers of circle, could present the fact. 3 ） for the sample circle with a designed spacing of 1.50 m×4.00 m and 2.00 m × 3.75 m, the optimum coordinate of the center of circle is （0, 0） m. 4） for the spacing of 2.00 m ×3.00 m, the optimum coordinate of the center of circle is （1.5, 0） m. 5） for the planting spacing of 1.20 m × 5.00 m, the optimum coordinate of the center of circle is （0, 1.0） m. 6） for the planting spacing of 2.00 m × 4.00 nl, the optimum center of circle is located in the middle of two neighboring rows with a coordinate of （0, 2.0） m. [ Ch, 3 tab. 11 ref. ]