Allometric scaling among tree components in Pinus massoniana stands with different sites

The WBE model was used to predict intraspecific scaling relationships among mean branch, needle, stem, root, and above-ground masses across eight stands of Pinus massoniana to test whether the scaling exponent was (1) dependent on site and (2) in accordance with WBE theory. The results showed that mean stem and root masses as well as mean above-ground and root masses scaled in a near-isometric manner across sites, except at two sites, which exhibited an exponent slightly less than unity. Mean needle mass scaled as 3/4 power of mean stem mass, except at one site, which exhibited an exponent slightly higher than 3/4. Mean branch mass scaled isometrically with mean stem mass at each site. These results supported the WBE theory. However, mean branch mass across sites scaled neither as 3/4 nor 1 power of mean stem mass, indicating that the scaling relationship predicted by WBE theory for these two components did not hold in P. massoniana stands.