中蒙毗邻草原区荒漠化时空动态研究

草原荒漠化是导致沙尘暴频发的重要原因，为掌握中蒙毗邻草原区荒漠化的时空动态，利用2001年、2010年和2020年的Landsat和Modis遥感影像、Albedo-NDVI特征空间及荒漠化监测差值指数(DDI)对该区域荒漠化动态特征及其驱动因素进行了研究. 结果表明:①2001—2020年中蒙毗邻草原区荒漠化现状呈“西高东低、南高北低”的空间特征. 其中，蒙古苏赫巴托尔省典型草原区以未荒漠化(ND)和轻度荒漠化(LD)为主，东戈壁省荒漠草原区以极重度荒漠化(ESD)和重度荒漠化(SD)为主；中国内蒙古自治区荒漠草原以中度荒漠化(MD)和重度荒漠化(SD)为主. ②2001—2020年研究区荒漠化总体呈逆转态势，净逆转面积(荒漠化逆转面积与加剧面积之差)约147 220 km2，其中2001—2010年逆转面积占34.89%，2010—2020年逆转面积占65.11%. ③研究区荒漠化逆转程度总体呈现“东高西低”格局，其中，中国内蒙古自治区的荒漠草原区逆转趋势最为明显. ④研究区荒漠化程度与年降水量呈极显著负相关(P < 0.01)，表明降水增加有助于区域荒漠化逆转；近20年来降水量波动增加决定了中蒙毗邻草原区土地荒漠化总体呈逆转态势，而中国在中蒙毗邻草原区实施的多项生态保护工程有效加速了荒漠化逆转速率. 研究显示，实施荒漠草原区的生态保护和修复政策可有效遏制荒漠化的发展并促进荒漠化逆转，在巩固我国荒漠化治理政策的同时，应加强与邻国合作，以防治境外荒漠化程度加重导致的沙尘暴灾害. 

Temporal and Spatial Dynamics of Desertification in Adjacent Steppe of China and Mongolia

Land desertification is one of the most important driving factors leading to the frequent occurrence of dust and sandstorms (DSS) in the adjacent steppe of China and Mongolia (ASCM). To reveal the dynamic changes of land desertification and its mechanism in ASCM, we interpreted Landsat images and Modis image of 2001, 2010 and 2020, and constructed desertification monitoring difference index (DDI) to analyze the temporal and spatial changes of land desertification in ASCM over the past 20 years. The results showed that: (1) the land desertification in ASCM presented the spatial characteristics of 'high in the west and low in the east, high in the south and low in the north'. Among them, the typical steppe in Sukhbaatar Province of Mongolia was dominated by non-desertification (ND) and light desertification (LD), the desert steppe in Dornogovi Province of Mongolia was dominated by extreme severe desertification (ESD) and severe desertification (SD), while the desert steppe in the Inner Mongolia Autonomous Region of China was dominated by moderate and severe desertification (MD & SD). (2) In the past 20 years, the area of desertification in ASCM showed a reversal trend, and the net reversal area (the difference between the reversal area and the aggravated area) was about 147, 220 km2, of which the reversal area during 2001-2010 accounted for 34.89%, while the reversal area during 2010-2020 accounted for 65.11%. (3) The desertification reversal pattern in ASCM generally presented a pattern of 'high in the east and low in the west'. The regions with the most obvious reversal trend were mainly distributed in the desert steppe of Inner Mongolia Autonomous Region of China. (4) There was a significantly positive correlation between the degree of desertification reversal and annual precipitation (P < 0.01), indicating that the increase in precipitation contributed to the desertification reversal in ASCM. The fluctuating increase in precipitation in the past 20 years determined the overall reversal of land desertification in ASCM. Meanwhile, a number of ecological protection projects implemented in the adjacent grassland areas of China effectively accelerated the rate of desertification reversal. This study shows that the ecological restoration projects can effectively restrict the development of desertification. It is necessary to strengthen cooperation with neighboring countries to prevent land desertification and DSS in ASCM.