蒙古高原土壤湿度时空变化格局及其对气候变化的响应

Temporal and spatial variation of soil moisture in the Mongolian Plateau and its response to climate change

土壤水作为一种重要的水资源,其时空分布和动态变化对植被的分布和生长状况具有显著影响。蒙古高原是典型的干旱-半干旱气候区,也是亚欧大陆温带草原的主要构成部分,气候变化导致的土壤含水量变化无疑会对草原生态系统健康及稳定产生直接影响;厘清蒙古高原土壤湿度时空特征及其对气候变化的响应有助于为生态保护相关政策的制定提供科学支撑。本研究基于GLDAS-Noah土壤湿度数据,运用线性回归分析、相关分析和Mann-Kendall(M-K)检验等方法,分析1982—2018年不同深度土壤湿度的时空格局、变化趋势及突变性等特征,并与CRU温度、降水数据相结合探讨土壤湿度对气象因子变化的响应。结果表明:①蒙古高原年均土壤湿度总体呈“东北高西南低”的空间分布格局,且有明显的高值区、过渡带和低值区;②近37 a来,蒙古高原0~10 cm(SM1)土壤湿度整体呈现不显著上升趋势,变化速率为0.002 m^(3)/m^(3)/10 a,M-K结果显示在2012年前后发生突变;10~40 cm(SM2)土壤湿度的下降趋势较显著,变化速率为-0.005 m^(3)/m^(3)/10 a,其突变发生在1996年左右;③基于像元尺度的相关性分析表明不同季节土壤湿度整体上与降水呈显著正相关关系,与温度呈显著负相关关系。

As an important water resource,soil water has a significant impact on the distribution and growth of vegetation by its temporal and spatial distribution and dynamic changes.The Mongolian Plateau is a typical arid-semi-arid climate zone,and it is also a major component of the temperate grasslands of the Eurasian continent.Changes in soil water content caused by climate change will undoubtedly have a direct impact on the health and stability of the grassland ecosystem.Clarifying the soil moisture of the Mongolian Plateau as well as the temporal and spatial characteristics and their response to climate change helps provide scientific support for the formulation of ecological protection related policies.Based on GLDAS-Noah soil moisture data,the authors used linear regression analysis,correlation analysis,and Mann-Kendall(MK)test methods to analyze the temporal and spatial patterns,changing trends,and mutation characteristics of soil moisture at different depths from 1982 to 2018.Combined with CRU temperature and precipitation data,the authors explored the response of soil moisture to changes in meteorological factors.The results are as follows:①The annual average soil moisture of the Mongolian Plateau is generally in a spatial distribution pattern of“high in the northeast and low in the southwest”,and there are obvious high-value areas,transitional zones and low-value areas.②In the past 37 years,the soil moisture of 0~10 cm(SM1)in the Mongolian Plateau has shown an insignificant upward trend,with a rate of change of 0.002 m^(3)/m^(3)/10 a.The results of MK showed that a sudden change occurred around 2012;soil moisture of 10~40 cm(SM2),the downward trend was more significant,the rate of change was-0.005 m^(3)/m^(3)/10 a,and its sudden change occurred around 1996.③The correlation analysis based on the pixel scale shows that the soil moisture in different seasons has a significant positive correlation with precipitation on the whole,and has a significant negative correlation with temperature.