Modeling daily photosynthesis of nine major tree species in northeast China

Abstract

Daily photosynthesis modeling, especially modeling a tree’s photosynthesis response to varied CO 2 concentrations is the basis of many models calculating ecosystem NPPs and simulating their structural changes under changing climatic scenarios. This is the case in the study on structural changes in forests in northeast China under climatically changing conditions. Four models were used here to simulate the daily photosynthesis of the most common nine tree species of the forests of northeast China. The models are (1) Chen’s model from Chen et al. (1999) [Ecol. Model. 124 (1999) 99]; (2) Daily-model-1, a new analytical model presented here based on the first model; (3) Daily-model-2, the numerical integration of the instantaneous photosynthesis rates modeled by Farquhar’s model; (4) Daily-model-3, the numerical integration of the instantaneous photosynthesis rate computed by equations presented in Chen’s model. The models were parameterized with field measured instantaneous photosynthesis rates using Farquhar’s model. The results show that (1) Chen’s model is not suitable for simulating daily photosynthesis for the nine tree species in northeast China. (2) Daily-model-2 is the best one in the three models with R 2, the square of the correlation coefficient between the measured and modeled, greater than 0.8 for the eight of the nine species. It is adequate to simulate the daily photosynthesis. (3) The Daily-model-1 and Daily-model-3 are also acceptable in modeling daily photosynthesis when setting the threshold at 64% of the R 2 or the 0.8 of the correlation coefficient. Particularly, the Daily-model-1 is very useful due to its easily obtained driving variables.