1. College of Geo-Exploration Science and Technology, Jilin University, Changchun 130026, China; 2. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; 3. Shaanxi Satellite Application Center for Ministry of Natural Resources of the PRC, Xi'an 710054, China

Since the 1970s, the soda saline-alkali soil region, which is located in the semiarid-arid region of the central Northeast China, has experienced drastic climate variability. Meanwhile, human activities and socio-economic development have led to an increase in water consumption. These factors have brought out considerable land use change and a lot of soil salinize-alkalization. The land use types were obtained from remote sensing images interpretation based on Landsat MSS in 1970s, TM, ETM in 1990s and 2010s. The characteristics of land use conversion and its response to climate change and influence of human activities were explored in the study area during 1970-2010. The results include: (1) The land use types had changed significantly, especially farmland and grassland, with annual growth rates of 0.31% and 0.35%, respectively. In terms of the saline-alkali land, the area increased greatly during 1970-1990, and its increase was mainly from grassland. There was a decrease from 1990 to 2010, and the loss of saline-alkali was replaced by farmland and grassland. (2) Climate change in the study area is obvious, showing a trend of decreasing precipitation and increasing temperature. The change of saline-alkali land area is closely related to the precipitation, with R2 = 0.78, passed a passing the 0.01 significance test. (3) The correlation of land use degree index and human activity index with saline-alkali land was not obvious, and the changes in these indices only reflected the land use patterns. Under sufficient rainfall, the saline-alkali land was developed into farmland by humans, which caused the decrease of the saline-alkali land. Therefore, climate change is the main driving force of land salinization in the study area.