丝绸之路经济带不同类型荒漠植被生长及其对气候变化响应

Growth and response to climate change of different dryland vegetation types in the Silk Road Economic Belt

结合GIMMS归一化植被指数(NDVI)、TRENDYv2模型模拟净初级生产力、GRACE陆地水储量变化(ΔS_(TW))及网格气候数据集,借助线性回归和偏相关分析,研究了1982—2015年丝绸之路经济带(the Silk Road Economic Belt,SREB)区域不同类型荒漠植被各季节生长动态及其对气候变化的响应规律.结果表明:1)升温导致SREB在1993—2015年的土壤含水量显著减少,2003—2015年陆地水储量下降,且ΔS_(TW)下降趋势增大,干旱加剧.2)不同类型荒漠植被生长存在差异,沙漠、半沙漠及荒漠灌丛区植被在1982—1992年呈增加趋势,1992年后降低;荒漠与苔原区植被仅在1992年前的生长季增加;沙漠与半沙漠区和荒漠草原区植被变化不显著.3)温度升高及降水减少引起的干旱胁迫是导致植被减少的主要因素,生长季前期降水有助于荒漠植被生长,促进作用从春季持续到夏季,秋季减弱.

Rapid climate change significantly affects dryland vegetation growth in the Silk Road Economic Belt(SREB),thus affecting global carbon cycle process.However,research on dryland vegetation growth and response to climate change are scarce.Therefore,combining remote sensing normalized vegetation index derived from GIMMS,simulated net primary productivity derived from TRENDYv2,terrestrial water storage change(ΔS_(TW))derived from GRACE and climate grid datasets,we used linear regression and partial correlation analysis to investigate seasonal growth dynamics of different dryland vegetation and underlying response mechanisms to climate change over SREB from 1982 to 2015.Global warming led to a significant decrease in soil water content from 1993 to 2015,and a decrease inΔS_(TW) from 2003 to 2015 in SREB.The decrease trend ofΔS_(TW) increased,indicating drought intensification.Growth divergence existed in different types of dryland vegetation.Growth in desert,semi-desert and desert shrub increased from 1982 to 1992 but decreased after 1992.Growth of desert and tundra only increased in the growing season before 1992,but growth change of desert and semi-desert and desert steppe were not significant.Drought stress caused by temperature rise and precipitation reduction was the main factor for vegetation reduction.Precipitation in pre-growing season significantly promoted growth from spring to summer,but weakened growth in autumn.