Abstract: Photosynthesis is one of the important physiological processes of plants, and it can reflect the response of plants to environmental change. Photosynthetic lightresponse model is a main way to evaluate the mechanism of the response of photosynthesis to light and obtain photosynthetic parameters. In this paper, leaf photosynthetic lightresponse curves of Quercus variabilis and Robinia pseudoacacia were measured using a LI-6400XT photosynthetic measurement system in the growing season of 2016 in the southern foot of the Taihang Mountain. The rectangular hyperbola (RH), nonrectangular hyperbola (NRH) and the rectangular hyperbola correction (YZP) models were used to simulate photosynthetic lightresponse curves of the shaded and sunlit leaves. Moreover, the lightresponse parameters fitted by the RH, NRH and YZP models were examined. Compared with the NRH and YZP models, the maximum net photosynthetic rate (P_max), initial light use efficiency (α) and dark respiration rate (R_d) fitted by the RH model were higher. The light saturation point (I_s) could not be derived from the RH model. Photoinhibition could not be simulated by the NRH model, and the value of P_max fitted by the NRH model was significantly larger than that obtained by the YZP model. However, α fitted by the NRH model was close to the measured one. Photoinhibition could be simulated by the YZP model. Compared with the shaded leaves, the P_max values of the sunlit leaves for Q. variabilis and R. pseudoacacia were 24.41% and 18.28% higher, and the α values of their shadedleaves were 22.08% and 15.41% larger, respectively. R_d of the shaded leaves of each species was higher than that of its sunlit leaves, and the R_d value of R. pseudoacacia shaded leaves was 7.13% higher than sunlit leaves. Both P_max , I_s and R_d were correlated with relative humidity and stomatal conductance of Q. variabilis, and α was primarily affected by relative humidity. Both P_max and I_s of R. pseudoacacia had significant positive relationships with relative humidity and G_s.

Key words: ecosphere, connectivity, estuarine delta, ecological function, habitat heterogeneity, habitat fragmentation, food web