1981—2019年全球陆地生态系统碳通量变化特征及其驱动因子

陆地生态系统碳汇显著降低大气CO₂浓度上升和全球变暖的速率，受人类活动和气候变化的影响，陆地生态系统碳通量具有强烈的时空变化，其估算结果仍存在较大的不确定性，不同因子的贡献尚不清晰。为此，利用遥感驱动的陆地生态系统过程模型BEPS模拟分析了1981—2019年全球陆地生态系统碳通量的时空变化特征，评价了大气CO₂浓度、叶面积指数(Leaf Area Index, LAI)、氮沉降、气候变化对全球陆地生态系统碳收支变化的贡献。1981—2019年全球陆地生态系统总初级生产力(Gross Primary Productivity, GPP)、净初级生产力(Net Primary Productivity, NPP)和净生态系统生产力(Net Ecosystem Productivity, NEP)的平均值分别为115.3、51.3和2.7 Pg·a^-1(以碳质量计，下同),上升速率分别为0.47、0.21和0.06 Pg·a^-1。全球大部分区域GPP和NPP显著增加，NEP显著上升(p<0.05)...

Characteristics and driving factors of global terrestrial ecosystem carbon fluxes from 1981 to 2019

The terrestrial ecosystem carbon sink plays an important role in retarding the increase of atmospheric CO₂concentration and global warming.Affected by human activities and climate change, the terrestrial ecosystem carbon fluxes exhibit strong spatial and temporal variations.Their estimates still have large uncertainties, and the contributions of different factors to their variations are still unclear.Therefore, using the remote-sensing-driven terrestrial ecosystem process model BEPS, the temporal and spatial variation characteristics of global terrestrial ecosystem carbon fluxes from 1981 to 2019 are simulated and analyzed, and the contributions of atmospheric CO₂concentration, leaf area index (LAI), nitrogen deposition and climate change to the change of global terrestrial ecosystem carbon budget are evaluated.From 1981 to 2019, the average values of global terrestrial ecosystem GPP (Gross Primary Productivity), NPP (Net Primary Productivity) and NEP (Net Ecosystem Productivity) are 115.3, 51.3 and 2.7 Pg·a^-1 (in terms of carbon quality, the same below), and the rising rates are 0.47, 0.21 and 0.06 Pg·a^-1, respectively.GPP and NPP increase significantly in most regions of the world, and the regions where NEP increases significantly (p<0.05) are significantly less than those for GPP and NPP.From 1981 to 2019, the accumulative global NEP is 105.2 Pg.The contributions of forests, savanna and shrub, crop, and grass are 76.4, 15.8, 9.4 and 3.6 Pg, respectively.The accumulative contributions of CO₂ concentration, LAI, nitrogen deposition and climate change to NEP are 58.4, 20.6, 0.7 and -43.6 Pg, respectively.The accumulative contribution of all four factor changes to NEP is 39.8 Pg.The rise of CO₂ concentration is the main contributing factor to the increase of NEP in global terrestrial ecosystem in recent 40 years, followed by LAI.