中国森林生态系统总初级生产力估算及分析

Estimation and Analysis of Gross Primary Productivity of China's For⁃est Ecosystem

森林生态系统是陆地生态系统的主体,量化森林生态系统总初级生产力(GrossPrimary Productivity,GPP)并分析其时空变化动态,有助于理解陆地碳动态发展及其对气候变化的响应机制,助力中国林业可持续发展。本研究采用敏感性分析法发现最大光能利用率--LUEmax是植被光合模型(VegetationPhotosynthesisMode;VPM)估算森林生态系统生产力的直接变量,敏感性高达100%。基于非线性最小二乘法,结合通量站点观测数据,优化VPM中最大光能利用率参数,并模拟了2000—2015年中国森林生态系统总初级生产力,进而分析了林区16年来GPP时空变化特征及其主要环境影响因子。结果表明:森林GPP年均值为1294.62 g C/m^(2)/year,以6.57 g C/m^(2)/year2(P<0.05)的速率显著上升,其环境因子光合有效辐射呈现增加趋势,而温度和降水量的年际变化不明显,森林GPP与光合有效辐射和温度呈显著正相关,与降水量呈负相关;在空间尺度上,在空间上超过80%区域的森林GPP年际变异由光合有效辐射和温度年际变异控制,光照和温度是我国森林生态系统GPP的主要影响因子。

The forest ecosystem is the main body of the terrestrial ecosystem.Quantifying the gross pri⁃mary productivity(GPP)of the forest ecosystem and analyzing its temporal and spatial changes will help understand the dynamic development of terrestrial carbon and its response mechanism to climate change,and help China Sustainable forestry development.This study uses the sensitivity analysis method to find that light energy utilization a direct variable for the vegetation photosynthesis model(VPM)to estimate the productivity of the forest ecosystem,with a sensitivity as high as 100%.Based on the nonlinear least squares method,combined with the flux site observation data,optimize the maximum light energy utiliza⁃tion parameter in the VPM,and simulate the gross primary productivity of China′s forest ecosystem from 2000 to 2015,and then analyze the characteristics of GPP spatio-temporal changes in the forest area over the past 16 years And its main environmental impact factors.The results showed that the annual av⁃erage value of forest GPP was 1294.62 g C/m^(2)/year,which increased significantly at a rate of 6.57 g C/m^(2)/year2(P<0.05).The environmental factor photosynthetically active radiation showed an increasing trend,while the temperature and precipitation The inter-annual variation is not obvious.The forest GPP is sig⁃nificantly positively correlated with photosynthetically active radiation and temperature,and negatively correlated with precipitation;on the spatial scale,the interannual variability of forest GPP in more than 80%of the regions in space is composed of photosynthetically active radiation and temperature.Interan⁃nual variation control,radiation and temperature are the main influencing factors of GPP in China′s for⁃est ecosystem。