Allometric models of DBH and crown area derived from QuickBird panchromatic data in Cryptomeria japonica and Chamaecyparis obtusa stands

Abstract

This study investigated the relationship between the estimates of the parameters of allometric models of diameter at breast height (DBH) obtained from a field survey and crown area derived from high-resolution satellite data in Cryptomeria japonica and Chamaecyparis obtusa stands, and stand variables such as stand age, stand density, mean stand DBH, mean stand tree height and relative spacing. Twenty-six sample plots of 0.04 ha were established in C. japonica and C. obtusa stands of 41 years of age and older. We constructed an allometric model between the crown area, obtained from QuickBird panchromatic data using a watershed method, and DBH measured during field surveys for each sample plot. The model can be expressed as E(y) = axb . The parameters a and b were estimated by the least-squares method for the plots. For C. japonica and C. obtusa, we performed a non-linear regression analysis to investigate the relationship between the estimates, â and , of the parameters of the allometric model and stand variables such as stand age, stand density, mean stand DBH, mean stand tree height and relative spacing, simultaneously. The coefficients of determination for C. japonica and C. obtusa were 0.84 and 0.87, respectively. The coefficients of determination obtained in the regression analysis to investigate the relationship between the DBH from a field survey and the DBH estimated from the predicted curve in the non-linear regression analysis were 0.82 and 0.86, respectively, for C. japonica and C. obtusa. The analysis revealed that the stand variables affected the parameters of the allometric models of the DBH and crown area derived from high-resolution satellite data in mature stands of C. japonica and C. obtusa.