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Scientia Silvae Sinicae ›› 2025, Vol. 61 ›› Issue (3): 86-99.doi: 10.11707/j.1001-7488.LYKX20240355

• Research papers • Previous Articles     Next Articles

Impacts of Optimizing Maximum Light Use Efficiency Parameter in VPM on GPP Simulation in Different Forest Ecosystems

Fuyu Yang,Mi Zhang*(),Wei Xiao,Jie Shi   

  1. Center on Atmospheric Environment, Nanjing University of Information Science and Technology School of Ecology and Applied Meteorology, Nanjing University of Information Science and Technology Nanjing 210044
  • Received:2024-06-11 Online:2025-03-25 Published:2025-03-27
  • Contact: Mi Zhang E-mail:zhangm.80@nuist.edu.cn

Abstract:

Objective: To analyze whether there are differences in the maximum light use efficiency (ε0 ), a key parameter in the vegetation photosynthesis model (VPM), in forest ecosystems of different climatic zones and the main reasons for such differences, and to select a parameterization scheme for the maximum light use efficiency that has general applicability. In order to deepen the knowledge of uncertainty in the process of estimating vegetation productivity in forest ecosystems and to provide a reference for improving model simulation accuracy and reducing the uncertainty of model parameters. Method: The maximum light use efficiency (ε0 ) was estimated using the four selected parameterization schemes, BPLUT look-up table method, Michealis-Menten light response curve equation fitting, maxmiun enhanced vegetation index (EVImax) of the growing season exponential fitting, and Mointeith equation estimation method. Simulation of gross primary productivity (GPP) of four forest ecosystems in China based on the estimation results of the four parameterization schemes, comparison with eddy covariance observed GPP, and evaluation of VPM simulation results by combining various model evaluation indexes (coefficient of determination R2, root mean square error RMSE, the Willmott’s index of agreement d and mean relative error MRE). Result: The ε0 values were (0.65±0.14g), (0.47±0.10), (0.44±0.09), and (0.69±0.12) g·mol, respectively for the Changbaishan, Qianyanzhou, Dinghushan, and Xishuangbanna. On the seasonal scale, compared with the GPP based on observation, root mean square error(RMSE) of GPP simulated by the optimal parameterization scheme for ε0 is reduced by 55.1%(Changbaishan), 38.1%(Qianyanzhou), 48.6%(Dinghushan), and 34.3%(Xishuangbanna), respectively, than that simulated by the least applicable parameterization scheme. On the inter-annual scale, the mean relative errors (MRE) of the GPP simulated by the optimal parameterization scheme were ?7.9%, ?24.3%, ?7.4%, and ?3.0% respectively at Changbaishan, Qianyanzhou, Dinghushan, and Xishuangbanna, which were lower than that (Changbaishan: 35.8%; Qianyanzhou: ?53.4%; Dinghushan: 29.8%; Xishuangbanna: 25.4%) simulated by the least applicable parameterization scheme. Conclusion: The ε0 values of different parameterization schemes at the same site vary greatly, and there are differences in the ε0 values between different sites under the same parameterization scheme. The main reasons for such differences are related to the structural properties of the parameterization schemes and the differences in hydrothermal conditions in different regions. Mointeith equation estimation method was the optimal parameterization scheme for ε0 in the Changbaishan, Qianyanzhou, and Dinghushan, and Maxmiun enhanced vegetation index (EVImax) of the growing season exponential fitting is the most applicable in the Xishuangbanna.

Key words: maximum light use efficiency, parameterization, VPM model, gross primary productivity

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