Error in Stem Volume Estimation using Tree Height and Several Upper-Stem Diameters of Standing Tree Measured with a Spiegel Relascope and Wheeler Pentaprism Caliper : In a 29-year-old Stand of Japanese Cypress (Chamaecyparis obtusa ENDL.)

Abstract

This paper describes the error in stem volume when estimated using standing tree height (h_s) measured with a wide-scale Spiegel Relascope and upper-stem diameters at i/10 of h_s from the ground level (d_<w0.ihs>, i=3, 5, 7) measured with a Wheeler Pentaprism Caliper. To measure tree height and upper-stem diameter, 15 sample trees in a 29-year-old stand of Japanese cypress (Chamaecyparis obtusa E_<ndl>.) were selected. The mean, standard deviation and range (minimum〜maximum) of error in h_s were -0.33m, 0.31m and -0.8〜0.5m, respectively. The means, standard deviations and ranges (minimum〜maximum) of error in d_<w0.ihs> (i=3, 5, 7) were 0.31cm, 0.57cm and -0.3〜1.3cm for d_<w0.3hs>, 0.37cm, 0.69cm and -0.9〜1.2cm for d_<w0.5hs>, -0.34cm, 0.79cm and -1.6〜1.1cm for d_<w0.7hs>, respectively. Such errors were common or slightly worse in both tree height and upper-stem diameter measurements. The mean, standard deviation and range (minimum〜maximum) of error in stem volume estimated using hs and d_<w0.ihs> (i=1, 3, 5, 7, 9) were 0.0023m^3, 0.0084m^3 and -0.0097〜0.0201m^3, respectively.