Photosynthetic characteristics of dominant tree species and canopy in the broadleaved Korean pine forest of Changbai Mountains

Based on the light-photosynthesis response measurement at leaf level, combined with over- and under-canopy eddy covariance measurements, research on photosynthetic characteristics of single trees and forest canopy was conducted. The relationship between light intensity and photosynthetic rates for leaves and canopy can be well fitted by a non-rectangular hyperbola model. Mongolian oak presented a high light compensation point, L-cp (28 mu mol(.)m(-2.)s(-1)), a light saturation point L-sp (> 1800 mu mol(.)m(-2.)s(-1)), and a maximal net photosynthetic rate P-max (9.96 mu mol(.)m(-2.)s), which suggest that it is a typical heliophilous plant. Mono maple presented the highest apparent quantum efficiency a (0.066) but the lowest, L-cp (16 mu mol(.)m(-2.)s(-1)), L-sp (approximate to 800 mu mol(.)m(-2.)s(-1)), and Pmax (4.51 mu mol(.)m(-2.)s(-1)), which suggest that it is heliophilous plant. Korean pine showed the lowest a value but a higher Pmax, which suggest that it is a semi-heliophilous plant. At the canopy level, the values of both a and Pmax approached the upper limit of reported values in temperate forests, while L-cp was within the lower limit. Canopy photosynthetic characteristics were well consistent with those of leaves. Both showed a high ability to photosynthesize. However, environmental stresses, especially high vapor pressure deficits, could significantly reduce the photosynthetic ability of leaves and canopy.