Simulation and Assessment of Sun-induced Chlorophyll Fluorescence and Gross Primary Production in Pinus sylvestris var.mongolica Plantation Based on the SCOPE Model
[Objective]To investigate the possibility of using SCOPE(Soil Canopy Observation of Photosynthesis and Energy fluxes)model to simulate the dynamic changes of sun-induced chlorophyll fluorescence(SIF)and gross primary productivity(GPP)in Pinus sylvestris var.mongolica plantation.[Methods]This study focused on a P.sylvestris var.mongolica plantation on the southern edge of the Horqin Sandy Land.Using coordinated observations SIF,GPP,and meteorological data,we simulated the diurnal and seasonal variations of SIF and GPP in the P.sylvestris var.mongolica plantation based on the SCOPE model.The model's performance was evaluated for a typical sunny day,a typical cloudy day,and the entire observation period.[Results]The results showed that using meteorological observation data and canopy parameters(incoming shortwave radiation,air temperature,atmospheric vapor pressure,CO2 concentration,and leaf area index),the SCOPE model can be driven to simulate the SIF and GPP in the P.sylvestris var.mongolica plantation.The R2 values for SIF simulations on a typical sunny and cloudy day were 0.42 and 0.52,with RMSE values of 0.19 and 0.18 W·m-2·μm-1·sr-1,respectively.The R2 values for GPP simulations on these days were 0.78 and 0.89,with RMSE values of 1.87 and 2.57 μmol·m-2·s-1,respectively.At the seasonal scale,the R2 values for SIF and GPP were 0.50 and 0.72,with RMSE values of 0.19 W·m-2·μm-1·sr-1 and 2.64 μmol·m-2·s-1,respectively.Throughout the observation period,the simulations of SIF(R2=0.31,RMSE=0.22 W·m-2·μm-1·sr-1)and GPP(R2=0.80,RMSE=2.42 μmol·m-2·s-1)on cloudy days were better than those on sunny days(SIF:R2=0.30,RMSE=0.26 W·m-2·μm-1·sr-1;GPP:R2=0.64,RMSE=3.64 μmol·m-2·s-1).Overall,the simulated SIF values were higher than the observed values,and the model tended to overestimate SIF at low intensities and underestimate it at high intensities.While GPP simulations demonstrated high accuracy,with slight underestimation for both low and high GPP and slight overestimation for intermediate values.[Conclusion]The SCOPE model is suitable for simulating daily and seasonal variations of SIF and GPP,with higher accuracy in simulations on cloudy days.The model's performance in simulating GPP in the P.sylvestris var.mongolica plantation is better than its performance in simulating SIF.The lower accuracy of SIF simulations is speculated to be due to the model being based on the radiation transfer process of broadleaf plants.Future efforts should focus on developing SIF radiative transfer models specifically for needle forests to establish a modeling foundation for the radiative transfer and fluorescence remote sensing monitoring of needle forests.
sun-induced chlorophyll fluorescencegross primary productionPinus sylvestris var.mongolicaSCOPE model
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