Abstract
The rectangular hyperbola, non-rectangular hyperbola, and monomolecular function as empirical models of photosynthetic light-response curve, were applied to data acquired from saplings of two Quercus species growing in the shaded undergrowth of a deciduous secondary-forest. The rectangular hyperbola gave unacceptably high estimates of the initial slope (φ) and the upper asymptotic maximum (Pmax) . The monomolecular function gave the best estimates for Pmax. However, the non-rectangular hyperbola was considered to be more reliable in estimating values of φ. In the three parameters estimated by the non-rectangular hyperbola, the interspecific difference in Pmax was almost negligible. As for θ, a curvature factor (dimensionless), Q. mongolica var. grosseserrata showed higher values although limited to a growth season and statistically nonsignificant. It was the parameter φ that the interspecific difference was significant, where Q. serrata showed higher values. From the estimation that the higher values of parameter φ act more effectively on the leaf carbon gain in heavily shaded forest floors, the saplings of Q. serrata were understood to be more shade-tolerant than Q. mongolica var. grosseserrata.
