Figure 5
Comparison of three allometric methods in estimating the leaf area index (LAI) for a hinoki cypress (Chamaecyparis obtusa) stand. (a) 20-year changes in the LAI of the stand obtained using the three methods. Each of the three allometries takes the form LA = CF × Elevation × XSlope, where LA (m2) is the leaf area per tree, X represents ACB (the site-specific pipe model) or ACB_Est (the site-specific and global qPipe models) of a tree, and CF is the factor correcting for bias regarding log-transformed regression. The values of the CF, elevation and slope differ between the three methods. See Supplementary Fig. S1 and Supplementary Table S1 in Supplementary Information S1 for coefficients of these allometries. For the site-specific pipe and qPipe models, allometric equations were formulated using 47 trees sampled near the stand where the LAI was estimated8. The allometry of the global qPipe model is the same as in Fig. 3b and Table 1(3b). LA for each tree each year in the hinoki stand was calculated by substituting measurements of ACB or ACB_Est of each tree each year into the three different allometries. The LAI for each year was then calculated by taking their sum and dividing by the stand area. (b) Relationship between the LAI of each year and the moving average of the mean temperature in July and August for the last 6 years (TJA6y), where the LAI was calculated using the site-specific qPipe allometry (open squres) or the global qPipe allometry of Fig. 3b (open circles). In the original paper, a significantly positive relationship was obtained8. For coefficients of the regression, see Supplementary Table S1 in Supplementary Information S1.
