青藏高原地气间二氧化碳通量观测研究进展OA

As a globally significant ecological security barrier and climate-sensitive region,the Qinghai-Xizang Plateau(QXP)plays a crucial role in regional and global carbon cycles.In recent years,climate warming and ecosystem changes have led to a complex pattern of concurrent strengthening and weakening in the plateau's car-bon sink capacity.To accurately assess the spatiotemporal patterns and mechanisms of carbon dioxide(CO ₂)fluxes over QXP terrestrial ecosystems,researchers have established a flux observation network centered on ed-dy covariance techniques since the 1980s.This network now covers various surface types including grasslands,shrublands,wetlands,and lakes.The integration of satellite remote sensing and machine learning has further fa-cilitated the upscaling from point-based measurements to regional estimates.Studies indicate that alpine mead-ows serve as stable and strong carbon sinks,with mean annual net ecosystem exchange(NEE)generally below-100 g·C·m ⁻ ²·y ⁻ ¹.In contrast,alpine steppes exhibit weaker sink strength,largely regulated by precipitation.Wetland and marsh ecosystems show high spatiotemporal heterogeneity in CO₂ fluxes,with hydrological dynam-ics and seasonal freeze-thaw processes driving their shifts between carbon sink and source states.Lakes on the plateau also act as carbon sinks,though the magnitude of CO₂ exchange varies significantly across lakes,reflect-ing integrated effects of climate,hydrology,and riparian vegetation.At the regional scale,grassland carbon sink strength is notably higher in the eastern and northeastern parts of the plateau compared to the arid west,indicat-ing control by climatic and ecological factors such as temperature,precipitation,and vegetation productivity.High spatiotemporal resolution remote sensing products reveal an overall strengthening trend in the grassland car-bon sink over the past several decades,primarily attributed to extended growing seasons and increased vegeta-tion cover under a warming and wetting climate.However,several uncertainties remain,including sparse distri-bution of flux stations in western and high-altitude regions,large parameter discrepancies among flux models,in-adequate representation of carbon emissions in permafrost zones,and a lack of systematic assessment of land use change impacts on CO ₂ fluxes.Moreover,interannual variability in ecosystem productivity and soil respiration introduces additional complexity in quantifying the long-term carbon balance of the plateau.Future studies ur-gently need to integrate multi-source observation technologies-such unmanned aerial vehicles,satellite remote sensing,and subsurface monitoring-to enhance long-term monitoring of land-atmosphere feedbacks and ecologi-cal processes,and develop mechanism-based models that couple human activities with ecological responses.These advances will provide a scientific foundation for improving the accuracy of carbon sink estimates on the plateau,understanding its dynamics,and supporting China's"Dual Carbon"strategy.