Abstract: The four mega-sandy lands are typical regions with desertification in China due to the instability and vulnerability of natural conditions.With the development of the ecological restoration projects,the area of desertification land in four sandy lands of China has been decreased since 2000.However,regional sustainable development still faces challenges due to the increasing pressure of socio-economic development and the limited carrying capacity of resources in the sandy lands.Therefore,evaluation and comparing the level of sustainability in four sandy lands is significant for targeted management and regional sustainable development.Based on the ecological footprint model developed by Wackernagel,this paper adopts an improved productive ecological footprint model to compare the actual area of land actually occupied by each region from the ecosystem each year (ecological footprint) and the land that provides biological and productive materials in the same area (ecosystem capacity),and then determines the pressure of human activities on the local ecosystem in the four sandy lands in order to analyze the sustainability of the four sandy lands.This study calculated productive ecological footprint and analyzed the sustainability of four sandy lands of China from 2000 to 2015.The results showed that per capita ecological footprint (PCEF) had a significant increasing trend among the four sandy lands.The annual increasing rate of PCEF in Mu Us Sandy Land was 20.85%,higher than other three sandy lands.The increasing amount of PCEF in Mu Us Sandy Land was highest (79.21 hm²·cap^-1).The PCEF of four main sandy lands was mainly dominated by fossil energy footprint and grassland footprint.The per capita ecological deficit (PCED),which is the difference of PCEF and per capita ecological capacity,was also growing from 2000 to 2015 with Mu Us Sandy Land having the highest value.The main reason for the increasing PCED was the mass production of fossil energy footprint.According to the correlation analysis of PCEF and other sustainability indices such as Human Development Index and the Engel's coefficient,people's demand for resources has been increased with the improvement of people's living standard,and the development of society and economy,which was still at the expense of the natural resources production and consumption.The balance between economic development and environmental protection in sandy zones remains a challenge.It is suggested that the mineral resource exploitation mode should be adjusted,and protection and utilization of grassland resources should be conducted according to the main structural types of the ecological deficits in different sandy lands.

Key words: four sandy lands, ecological footprint, ecological deficit, sustainability assessment