The sensitivity assessment of land desertification is one of important contents of monitoring, preventing and controlling desertification. This paper took the arid region of Northwest China as the study area. Based on the RS and spatial analysis technology of GIS, we built a comprehensive index system of desertification sensitivity for evaluation on "soil-terrain-hydrology-climate-vegetation". The spatial distance model (SDM) was used to calculate the desertification sensitivity index (DSI). Then, spatiotemporal change of land desertification sensitivity in the study area covering 2000, 2005, 2010 and 2017 was quantitatively assessed. On this basis, the main driving factors were analyzed by using the geographic detector. The results showed that: (1) terrain, soil, climate, vegetation and hydrology affected each other, which were the basic conditions for the distribution and changes of sensitivity to desertification in the study area. (2) On the whole, the desertification sensitivity showed a distribution pattern of low around and high inside. The low sensitivity regions were mainly distributed in the five major mountain ranges (i.e. Altai Mountains, Tianshan Mountains, Kunlun Mountains, Altun Mountains and Qilian Mountains), and Junggar Basin, Tarim Basin and Inner Mongolian Plateau belonged to the high sensitivity regions, including the back-land of Taklamakan Desert, Badain Jaran Desert and Tengger Desert. Besides, the spatial distribution of desertification sensitivity had obvious regionality, and high and low sensitivity regions had clear boundary and concentrated distribution. (3) In terms of spatiotemporal evolution, changes of desertification sensitivity since 2000 was mainly stable type, and the overall sensitivity showed a slow decrease trend, indicating that the potential desertification regions decreased year by year and some achievements had been made in the control of regional desertification. (4) Among the driving factors affecting study area, soil and climate played a direct role, which were the most important influencing factors, and vegetation was the most active and basic factor that changed desertification sensitivity. In addition, topography and hydrology played a role in restricting the changes of desertification sensitivity, while socio-economic factors were affecting the regional desertification sensitivity, and their effects were gradually strengthened. In general, desertification has been effectively controlled in the study area, and positive results have been achieved in desertification control. However, against the backdrop of intensified global climate change and new normal of socio-economic development, the monitoring, assessment and control of desertification in China still have a long way to go.

The reconstruction of land use/land cover change within small-scale areas during historical periods based on multi-source data is of great significance for obtaining an in-depth understanding of the mechanisms driving land use change and their effects on the environment and climate. Herein, we reconstructed the evolution of settlement patterns at the basin scale, the amount and spatial distribution of cropland at the settlement scale, as well as the cropland pattern at the basin scale. Typical small and medium-scale watersheds in the mountainous areas of Yunnan Province were used as the study area. Abided by historical documents, field investigation data, historical geographical research results, archival data, modern statistical data, and basic geographical data, we considered regional natural factors (slope and altitude) and anthropogenic factors (population, policies, agricultural technology, and distance between croplands and settlements) and built a gridded model for cropland reconstruction in historical periods in the small-scale mountainous areas. We then reconstructed gridded cropland patterns with clear temporal and spatial attributes for the past 300 years. The results showed that: (1) over the past 300 years, the area of cropland in the Zhangjiu River Basin has increased 6.3 times, and the reclamation rate increased from 2.1% in 1700 to 15.6% in 1978. (2) The cropland area differed considerably in various terrains. The cropland area in mountainous and semi-mountainous areas was the largest and increased rapidly, whereas the cropland area in the flatlands and the middle and lower reaches of the valley area increased slowly, which was caused by a combination of factors, such as the natural environment, population, policies, and agricultural technology. (3) The results were verified using the total cropland area and per capita cropland area. The gridded reconstruction model devised in this study can be used as a reference for simulating historical cropland in small-scale areas with distinct spatial and temporal attributes using gridded datasets.

Landuse change is an essential driving force of global climate change. Dynamic simulations are helpful for understanding and explaining the changing rules and characteristics of the land system. The "Grain to Green Program" (GTGP) is a critical contributing factor to landuse change in China's mountainous areas. Presently, the deficiency of integrated social and spatial approaches in the simulation of the "GTGP" limits the spatial accuracy of the social benefits simulation and its subsequent research. The accurate simulation of the "GTGP", by combining social and spatial approaches, can provide scientific evidence for the completion of this project. Taking Tongdu Town, Dongchuan district in Yunnan province as the research area, this study identified three kinds of agents: farmers, farmer households, and the government based on census, geographical information and field survey data. In addition, this research constructed a regional spatial simulation of the "GTGP" implementation based on agent-based model. It conducted spatial simulations of Tongdu Town from 2011 to 2015, including the annual income of farmer households, the willingness of farmer households and the government towards the program, and the spatial processes implementation of the "GTGP". The results showed that the implementation of the "GTGP" was mainly related to the slope, the traffic, and the income of farmer households. Specifically, 81.47% of the "GTGP" program conducted in this areas was on slopes of 25°-30°, and 56.37% of them was 0-2 km away from the road with convenient traffic conditions, and the proportion of the "GTGP" areas with low annual income of farmers was relatively high. The correlation between "GTGP" areas and soil fertility was low. The implementation of the project significantly enhanced the revenue of the study area, with an average household income increase of 1475 yuan from 2010 to 2015. The spatial accuracy of the simulation results was 91.12%. The spatial simulation methods constructed in this study can provide references for the implementation of the "GTGP" in other regions, which can contribute to applications of ecological protection and targeted poverty alleviation programs in China.

As a part of the supply of ecosystem services, land and water resources are an important factor restricting economic development in mountainous areas. Taking the Hengduan Mountains Area as a case study, we evaluated the degree of matching between land and water resources and economic development using the Gini coefficient method. Furthermore, the sensitivity of economic growth to land-water factors was analyzed by establishing an extended Cobb-Douglas function based on the individual stochastic effect model. In addition, the growth drag model was introduced to measure the restriction of land-water resources on economic development in the study area quantitatively. The research produced several important results: (1) From 2006 to 2015, the fluctuation ranges of the Gini coefficient between land and water resources and gross domestic product (GDP) in the study area were 0.265-0.298 and 0.389-0.424, respectively. The satisfaction by water resources in different industries was relatively reasonable, but the utilization of land resources for economic development was not satisfactory, especially in the secondary and tertiary industries. (2) The sensitivity analysis results showed that the elasticity of land resources in the region was about twice that of water resources. The cumulative contribution rate of land resources was significantly higher than that of water resources, and the contribution of land resources to economic growth was greater than that of water resources. (3) The average growth drag values of land and water resources were 0.012 and 0.022, respectively, indicating that both land and water resources had obvious restraining effects on the economic development, which was greatly restricted by land resources. The research showed that effective development of mountainous areas in China should focus on the sufficient land-water resources demanded by economic growth. Utilizing the potential of land-water resources and increasing their supply can reduce restriction on economic growth and promote sustainable development.

Russia is rich in oil, gas resources, and areas with unproven reserves, and also has a huge potential for application of oil and gas resources. As climate change intensifies, it would be possible for navigation in Arctic, and Russia hopes to vigorously develop its energy trade through the Arctic Sea Route. In this study, the Russian transportation network was regarded as the focus of connecting resources and ports, and spatial statistical method was used to describe the spatial distribution characteristics of Russian oil and gas resources. By means of grid cost distance, weighted average travel time and potential location advantage, the accessibility of oil and gas resources in each port was quantified, and the conclusions were drawn as follows. (1) The oil and gas resources were concentrated in the Western Siberian Plain. The accessibility of ports in the whole region of Russia was characterized by "high in the west and low in the middle". (2) The resource accessibility of the northeast port of Russia was generally poor, and the resource accessibility of the northwest port was better than that of the northeast one. Taking oil and gas resources, geographical location and project cooperation into account, we focused on the construction of three ports: Sabetta, Murmansk and Vladivostok. (3) The density of the nearby traffic network affected the resource accessibility of the port. With the climate warming, the melting of frozen soil, and the gradual implementation of the "Polar Silk Road" between China and Russia, it would be possible for further improvement in the resource accessibility of ports in the Far East region of Russia in the future.