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The estimate by the plotless sampling is originally that of the total basal area per unit area of stand. But practically, the total volume per unit area is desired. There are two methods of estimating... the volume per unit area from the basal area per unit area, i.e. the ratio estimate method and the regression method. These methods belong to the double sampling method. The method by L. G. Grosenbaugh who introduced the plotless sampling into t he U.S.A. is the ratio estimate method. In his method, the ratio of v/g obtained is larger than the true ratio for the stand, since the trees obtained by the plotless sampling are used as the small sample. To correct this, the trees of the small sample must be weighted by l/g. This correction gives an unbiased estimate va1ue. The difference between the two methods, however, is negligible in the practical use. The same condition applies to the regression estimate method. After all, the best method by the plotless sampling is the corrected regression estimate method and the worst is the uncorrected ratio estimate method or Grosenbaugh's method. But in the practical use the uncorrected ratio estimate method can be used. Comparing the plotless sampling with the plot sampling for this stand (Shiragadake Sampling Survey Experimental Forest, Section 46), the plotless sampling of basal are' a factor of 4 (as usually used) gives more precise estimate than the $ 10 m \times 20 m $ plot sampling. The precision of estimate by plotless sampling changes with the coefficient of variation, the average diameter, the basal area factor and the number of the sampling points, Therefore, if the stand is constant, required precision can be obtained by appropriately selecting the basal area factor and the number of sampling points.続きを見る
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I 緒言 II 資料 III Plotless Samplingによる材積推定 1 比推定法 2 回帰推定法 IIII Plotless samplingによる材積推定の誤差 1 比推定法 2 回帰推定法考察 V 数値的結果並びに考察 VI Plotless SamplingとPlot Samplingとの精度の比較 1 胸高断面積推定 2 材積推定 3 本数推定 VII 結言 参考文献 Resume
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Mendeley出力
KJ00005470605