森林調査に利用する計算図表の作成
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Two allinement charts were prepared for forest survey.1. Fig. 1 is an allinement chart of forest area (A ha), stand factor (f), and the number of sample plots (n) required to obtain 10% sampling error (sample size 0.01 ha). The relation of plot size (a ha), forest area (A ha), stand factor (f), the number of sample plots (n) and sumpling error percent (e%) is as follows.n=(Af)/(e^2A+af) When we know forest area (A) and stand factor (f), we can estimate the number of sample plots (n) required to obtain 10% sampling error in plot size 0.01 ha from Fig. 1.The relation of the coefficient of variation (C) and stand factor (f) is √<f>=2 C and illustrated in Fig. 2.2. Fig. 3 is an allinement chart of forest area (A ha), required plot numbers (n) and sampling point intervals (1 m). The relation of A, n and l is as follows.l=√<A/n>×100 When we know forest area (A ha), and required plot numbers (n) from Fig. 1,we can estimate the sampling point intervals (1 m) required to obtain the number of sample plots in a forest area from Fig. 3.3. The pine stand (Pinus densiflora SIEB. et ZUCC.) in Kodo district Niigata city (A=0.56 ha) was measured by the use of the allinement charts.As A is 0.56 ha and f is 0.40,n is 23 from Fig. 1. As A is 0.56 ha and n is 23,l is 16 m from Fig. 3. Results of sampling survey were as follows.x^^-=196.3 m^3/ha (mean volume per ha).S=62.02 m^3/ha (standard deviation of the estimate).S_<x^^->=9.92 m^3/ha (standard error of the estimate).t(0.05,d.f.=22)=2.080 tS_<x^^->=20.63 m^3/ha (standard error in significant level 5%).C=31.5% (coefficient of variation).f=0.40 (stand factor).e=(tS_<x^^->/x^^-)×100=10.5% (sampling error percent).Results obtained were as might have been expected.
- 一般社団法人日本森林学会の論文
- 1953-07-25
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