2020—2050年CO_(2)施肥效应促进全球陆地生态系统碳吸收

CO_(2) fertilization promoting the carbon uptake of global terrestrial ecosystems in 2020—2050

CO_(2)施肥效应是全球变绿的主要原因,随着大气中CO_(2)浓度的持续增加,预估未来气候变化条件下,CO_(2)施肥效应对陆地生态系统的影响对减缓全球气候变化具有重大意义。基于未来气候情景数据和Farquhar模型,并结合生态过程模型BEPS(Boreal Ecosystem Productivity Simulator),定量化研究2020—2050年CO_(2)施肥效应对全球叶面积指数(LAI)和总初级生产力(GPP)的影响。研究结果显示2020—2050年,在RCP2.6、RCP4.5和RCP8.5气候情景下,CO_(2)施肥效应导致的LAI年际变化趋势分别为0.002、0.003和0.005 m^(-2)m^(-2)a^(-1);三个气候情景下CO_(2)施肥效应对LAI的影响为CO_(2)每增加0.1%,LAI平均增加约8.1%—9.2%,由此导致GPP对应增加7.9%—14.6%;由CO_(2)施肥效应导致的全球LAI的增加对未来GPP年际变化趋势的贡献分别为66.7%、48.7%和57.1%。表明在未来气候变化情景下,LAI的增加仍然主要受CO_(2)施肥效应的影响,CO_(2)施肥效应导致的LAI的增加将显著促进全球陆地生态系统碳吸收。

CO_(2) fertilization is the main reason for global greening.With the persistent increase in CO 2 concentration,it is critically significant to evaluate the effect of CO_(2) fertilization on the global terrestrial ecosystem.Gross primary productivity(GPP)quantifies the photosynthetic uptake of carbon by terrestrial ecosystems,and it is the basis of the global carbon cycle.Leaf area index(LAI)is a vegetation structural parameter that modulates the interaction between the land surface and the atmosphere and therefore is used in many terrestrial biosphere models.LAI is a critical parameter for leaf-to-canopy upscaling in the terrestrial biosphere models at the regional and global scales.Therefore,a reliable estimation of CO_(2) fertilization on LAI is crucial for understanding and predicting the terrestrial carbon cycle under future climate change.Due to the complexity and spatiotemporal difference in the global terrestrial ecosystems,there are still large uncertainties in simulating global LAI based on phenology and carbon dynamic allocation in Earth system models.Thus,in this study,we used the future scenario climate data,combined with the Farquhar and Boreal Ecosystem Productivity Simulator(BEPS)model to investigate the effect of CO_(2) fertilization on the global LAI and GPP during 2020—2050.The results showed that for RCP2.6,RCP4.5,and RCP8.5 scenarios,the CO_(2) fertilization led to the global LAI interannual trends were 0.002,0.003,and 0.005 m^(-2)m^(-2) a^(-1),respectively.The LAI increased 8.1%—9.2%,resulting in a corresponding increase in GPP of 7.9%—14.6%per 0.1%CO_(2) concentration.The contributions of LAI to the global terrestrial ecosystem GPP were 66.7%,48.7%,and 57.1%,respectively.It shows that CO_(2) fertilization is still the primary reason for increasing LAI under future climate scenarios.The increase of LAI caused by CO_(2) fertilization will significantly promote the carbon uptake of global terrestrial ecosystems.