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Identifying the spatial changes in farming–pastoral ecotone (FPE) is of utmost importance for the development of strategies for ecological protection in ecologically fragile areas. This study employed spatial autocorrelation and spatial clustering techniques to map FPE at the pixel scale using CLCD data with a spatial resolution of 30 × 30 m in the years 1985, 2000, and 2021, and then analyzed the changes of the FPE in northern China. The results showed that the FPE is mainly located at the border between the Inner Mongolia Autonomous Region and the adjacent provinces, which is along the Hu-line and the 400-mm isohyetal line. The area of the FPE was 63.94 × 104 km2, 62.90 × 104 km2, and 53.81 × 104 km2 in 1985, 2000, and 2021, respectively, accounting for 6.7%, 6.6%, 5.6% of the total land area in China. The FPE boundary moved northwestward during 1985–2021, demonstrating retreating, fragmenting, and shrinking tendencies. The decreased areas and the moving distances of the gravity center are six times and four times greater during 2000–2021 than that during 1985–2000, respectively. Moreover, the discontinuous change in FPE was mainly due to the increase in forest land, especially for the conversion of grassland to forest land. Our findings provide guidance for the construction of ecological civilization and the optimization of ecosystem structure in the farming–pastoral ecotone. [ABSTRACT FROM AUTHOR]

• AWSI was applied to investigate impacts of precipitation variations on agricultural water scarcity. • Extremely dry conditions intensified AWSI by 31% under the historical climate in China. • Future climate change would increase AWSI in many China's provinces, particularly in Inner Mongolia. • Impacts of future climate change on AWSI exceeds the historical extremely dry conditions. • Southwestern China had low AWSI in the historical period, but AWSI there would largely increase under future dry conditions. Both blue water and green water contribute to agricultural water scarcity, which is subjected to impacts of precipitation variations in the context of climate change. However, an explicit quantification of the possible effects of precipitation variations on agricultural water scarcity index (AWSI) under historical and future climate is absent. In this study, we applied an integrated AWSI, which incorporates blue water and green water, to estimate agricultural water scarcity in China and to determine the association of AWSI with precipitation variations over the historical (1971–2010) and future (2031–2070) periods. Precipitation variations have substantial effects on changes in AWSI. Especially during extremely dry years with precipitation anomaly lower than −2 standard deviation, changes of AWSI from the multi-year average could be as high as 31%. Future climate change would further intensify AWSI and amplify the effects of precipitation variations, particularly in Inner Mongolia with changes of AWSI over 200%. Southwestern China could also experience expanding agricultural water scarcity under future climate scenarios. Improving irrigation efficiency has potential to alleviate water scarcity by up to 30%. This study provides valuable information for scientists and policy decision makers to cope with the impacts of precipitation variations on AWSI. [ABSTRACT FROM AUTHOR]