植被光合呼吸模型在长白山温带阔叶红松林的优化及验证

Optimization and validation of the vegetation photosynthesis and respiration model in a temperate broad-leaved Korean pine forest

植被光合呼吸模型(VPRM)关键参数的确定和优化是准确计算生态系统净CO_2交换(NEE)的基础。利用中国通量观测研究联盟(China FLUX)长白山站温带阔叶红松林2005年的通量观测资料,对VPRM的4个参数(最大光能利用率ε_0、光照为半饱和条件下光合有效辐射值PAR0和呼吸参数(α、β))进行优化,并使用2006年的观测资料对参数优化前后的模拟结果进行评估。结果表明:参数优化后,VPRM能够较好地模拟长白山地区2006年植物生长季NEE的变化。对30min NEE模拟的平均误差为-1.81μmol m^(-2)s^(-1),相关系数为0.72,模拟NEE平均日变化的峰值约为观测值的91%,相关系数为0.97。但在植物非生长季模型对森林NEE的模拟效果较差。模型模拟30min NEE的平均误差为0.39μmol m^(-2)s^(-1),相关系数仅为0.10,并且模拟低估NEE平均日变化白天吸收峰值约82%,日变化模拟值与观测值的相关系数为0.50。通过分析不同天气个例,发现模型可以较好地模拟晴天条件下NEE的变化,而对阴雨天NEE的模拟误差较大。该研究有利于提高VPRM模型对温带落叶阔叶林NEE的模拟能力,对进一步改进区域陆地NEE的模拟具有重要意义。

Optimizing key parameters of the Vegetation Photosynthesis and Respiration Model（ VPRM） is crucial for accurately calculating net ecosystem CO2 exchange（ NEE）. The objectives of the present study were to use data measured in temperate broad-leaved Korean pine forest at Changbaishan（ CBS） in 2005 to optimize four VPRM parameters,maximal light use efficiency（ ε0）,half-saturation value of photosynthetically active radiation（ PAR0）,and two respiration parameters（ α,β）,and to evaluate the simulation results using data measured in 2006. Using the optimized parameters,the VPRM was able to accurately simulate variation in net ecosystem CO2 exchange（ NEE） during the growing season of2006. For 30 min NEE simulation,the mean bias was-1. 81 μmol m^-2s^-1,and the correlation coefficient was 0.72. In regards to daily variation,the peak NEE value was underestimated by 9%,and the correlation coefficient was 0. 97.However,the VPRM was unable to accurately simulate NEE during the non-growing season. During this period,the mean bias for 30 min NEE simulation was 0.39 μmol m^-2s^-1,and the correlation coefficient was 0.10. In regards to daily variationduring the non-growing season,the peak NEE value was underestimated by 82%,and the correlation coefficient was 0.50.Furthermore,we also found that the VPRM is better suited for simulating NEE on sunny days than on cloudy or rainy days.The present study facilitates application of the VPRM to studies of the NEE of temperate broad-leaved Korean pine forest and has important significance for improving simulation of regional terrestrial ecosystem NEE.