关键词: 林业经营, 材积计算

Abstract:

The systematic underestimation error of forest timber by using standard sample trees was pointed out. And 2 correction methods were proposed with easy estimation of the correction factors from the sampling data. The traditional formula is In contrast. the corrected formula is where V_TE and are V_TE¹ the estimated timber volume for whole quadrat using the original formula and the corrected formula respectively. V_BK and A_BK are respectively the measured timber volume and breast height cross-sectional area of K'th standard sample tree. A_T is the total breast height cross-sectional area in the quadrat; h_B and d_B are respectively the height and breast diameter of the tree with average breast height cross-sectional area; d_w is the average breast height diameter weighted by breast height cross-sectional area; an db is the slope of the tree height curve at d=d_B, d_B, h_B and d_w can be es timated by sampling in the quadrat. b can be obtained either from given tree height curve or by applying linear regression to the same sample data for estimation of d_B, h_B and d_w. The second correction of tEe formula has exactly the same form as the above equation, except the n standard sample trees are selected to have breast height diameters closest to the average breast height diameter in the quadrat. Thus d_B and h_B should be replaced by statistically estimated average breast height diameter and average tree height in the quadrat.

Key words: Timber calculation, Forestry