Simulation On Photosynthesis And Carbon Flux Of The Plantation In The Hilly Area In North China

Photosynthesis is one of the important physiological processes of plants,and it can reflect the response of the plant to the change of environment.Photosynthetic light-response model is the 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 and photosynthetic CO2-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(Ye model)models were used to simulate photosynthetic light-response curves and photosynthetic CO2-response curves of the shaded and sunlit leaves.Compared with the NRH and Ye model,the maximum net photosynthetic rate(Pmax),the initial light use efficiency(a)and dark respiration rate(Rd),the maximum net photosynthetic rate(Amax),the initial carboxylation rate(?),light respiration rate(Rp),CO2 compensation point(CCP)fitted by the RH model were higher.The light saturation point(Is)and CO2 saturation point(CSP)cannot be derived from the RH model.Photoinhibition could not be simulated by the NRH model,and the value of Pmax and Amax fitted by the NRH model was significantly larger than that obtained by the Ye model.However,?,?,Rp and CCP fitted by the NRH model was close to the measuredone.Photoinhibition can be simulated by the Ye model,it do well on Pmax,Amax and CSP.Compared with the shaded leaves,the Pmax and a values of the sunlit leaves were higher.Rd of the shaded leaves were more than that of the sunlit leaves,especially on Robinia pseudoacacia.Amax,Rp and CCP of the shaded leaves of Quercus variabilis were lower than those of the sunlit leaves.Amax,Rp and CCP of shaded leaves of Robinia pseudoacacia were more than those of the sunlit leaves.Compared with the sunlit leaves,the ? values of the shaded leaves for Quercus variabilis and Robinia pseudoacacia were higher than those of the sunlit leaves.Pmax,?,Rd and Is of Quercus variabilis and Robinia pseudoacacia were correlated with relative humidity(RH)and stomatal conductance(Gs).For Robinia pseudoacacia,Rp and CCP had linear relationships with photosynthetic active radiation(PAR),and ? had a significant positive relationship with RH and Gs.? of Quercus varlabilis was linearly correlated with PAR.The relationships between CCP of Quercus variabilis and temperature(T)were remarkable.Amax of Quercus variabilis had significant positive linear relationships with and Gs.This paper is of great significance to study the physiological and ecological adaptation mechanism of forest ecological system.CABLE model is the world's land surface process model,and distinguishes between shaded leaves and sunlit leaves.Through the improvement of photosynthetic modle,this paper is to improve the simulation results of the model.There still exists certain error between the model simulation results and the measured values,the value of RMSE was bigger.The range of correlation coefficient of simulated values and the measured flux values was between 0.7 and 0.9,the range of d was 0.8 and 1.