亚洲半干旱区碳水通量时空格局及驱动因素

Spatial-temporal pattern and driving factors of carbohydrate flux in semi-arid region of Asia

亚洲半干旱区生态系统敏感,环境问题突出,作为全球近30年来碳水通量变化最大的区域,明确其碳水通量的时空分布格局和驱动因素对区域资源管理与可持续发展、全球气候变化等领域具有重要意义。基于植被与土壤湿度的联合同化产品(LPJ-Vegetation and soil moisture Joint Assimilation,LPJ-VSJA),结合研究区植被及气象数据,分析了亚洲半干旱区2010—2018年碳水通量植被总初级生产力(GPP)、蒸散发(ET)和水分利用效率(WUE)的时空变化、年际变化贡献率以及驱动因素。结果表明:(1)2010—2018年亚洲半干旱区年均GPP、ET、WUE空间格局总体呈“双夹型”,中高纬度与低纬度地区的碳水通量值大于中纬度区域。(2)2010—2018年GPP、ET和WUE的年际变化总体都呈现增长趋势,但只有GPP呈现显著增长趋势(P<0.05),增速为7.82 g C m^(-2)a^(-1)。(3)WUE的年际变化表现为总体先增加后减少,正值中农田对WUE年际变化贡献率最大(54.6%),森林生态系统在面积占比仅有草原五分之一的情况下仍有与草原相近的贡献率。(4)在亚洲半干旱区被植被所覆盖的40%区域中,WUE与温度、降水和光合有效辐射(PAR)显著相关(P<0.05),降水为亚洲半干旱区WUE的主导气象因素,降水和PAR共同影响了大部分区域植被的生长状况,对WUE多为负向影响;温度对WUE主要为正向影响。气象因子对WUE影响的区域差异性较明显。研究结果可为亚洲半干旱区制定植被和水资源管理策略、实现可持续发展提供参考。

The semi-arid region of Asia is sensitive to ecosystem and has prominently environmental problems.As the region with the largest change of carbon and water fluxes in the past 30 years,it is of great significance to clarify the spatial and temporal distribution pattern and driving factors of carbon and water fluxes for regional resource management and sustainable development,global climate change and other fields.Based on the combined assimilation product of vegetation and soil moisture(LPJ-Vegetation and soil moisture joint assimilation,LPJ-VSJA),combined with the vegetation and meteorological data of the study area,this paper analyzed the spatiotemporal variation,annual variation contribution rate and driving factors of carbon and water fluxes Gross Primary Productivity(GPP),Evapotranspiration(ET),and Water use efficiency(WUE)in the Asian semi-arid region from 2010 to 2018.The results show that:1)the spatial patterns of GPP,ET and WUE in the Asian semi-arid region from 2010 to 2018 were“Double Clip”,and the carbon and water fluxes in the mid-high and low latitudes were greater than those in the middle latitudes.2)From 2010 to 2018,the annual changes of GPP,ET and WUE showed a growth trend,but only GPP showed the significant growth trend(P<0.05),with a growth rate of 7.82 g C m^(-2)a^(-1).3)The contribution rate of farmland to WUE was the largest(54.6%),and the contribution rate of forest ecosystem was similar to that of grassland when the area of forest ecosystem accounted for only one fifth of grassland.4)The WUE was significantly correlated with temperature,precipitation and photosynthetically active radiation(PAR)in 40%of the semi-arid areas of Asia covered by vegetation(P<0.05).Precipitation was the dominant meteorological factor of WUE in the Asian semi-arid region.Precipitation and PAR affected the growth of vegetation in most regions,and had a negative impact on WUE;Temperature has a positive effect on WUE.The influence of meteorological factors on WUE had obviously regional differences.The results of this study can provide reference for formulating vegetation and water resources management strategies,as well as achieving sustainable development in Asian semi-arid region.