Many scholars have conducted in-depth research on the theme of land use change and food security, and formed fruitful research results, but there is a lack of quantitative analysis and comprehensive evaluation of research achievements. Therefore, based on the relevant literature on the theme of land use change and food security in the core collection of the Web of Science (WOS) database, this paper takes the advantage of CiteSpace and VOSviewer bibliometric software to draw the cooperative network and keyword cooccurrence map to analyze the research progress and frontier. The results reveal that: (1) The research started in 1999 and can be divided into three stages: initial research, rapid development, and a stable in-depth stage. This topic has increasingly become a research hotspot in the academic community. (2) The distribution of research institutions is concentrated and forms a small cluster, and the research networks between developed and developing countries have been established, and developed countries are in the core position, but the cooperation network is not prominent. (3) The research content is becoming increasingly organized and systematic, and the research hot topics are divided into seven aspects. (4) The research area of the subject covers multiple levels, such as global, national, and specific natural geographical regions, and has formed a research system of geographic information technology and satellite remote sensing technology. It also presents the trend of cross integration with economics, land management and soil science. In the future, theoretical innovation still needs to be strengthened, and we should strengthen the research on the impact of agricultural chemical fertilizers on food security and study the impact of urban expansion on land use change.

With the rapid development of China’s economy and the acceleration of urbanization, the rapid expansion of urban space has led to a growing demand for land that has resulted in the destruction and expropriation of a large amount of ecological land in China. In the face of the current situation of China’s resource constraints, environmental degradation, and ecosystem destruction, it is necessary to thoroughly study the territorial ecological space of China and its evolution rules. Based on previous studies on the classification of ecological land use, this study proposes the concept of territorial ecological space and distinguishes it from urban space and agricultural space. A matching ecological space classification system has been established, which may help in understanding the ecosystem model and related ecological processes. According to the constructed ecological space classification system, ecological spatial data processing was conducted. The standard deviation ellipse model was used to analyze the pattern of various ecological spaces in China and the migration of their barycenter. The results of the study show the following: 1) China’s territorial ecological space area showed a downward trend from 2000 to 2015. From the aspect of flow, the area of ecological space mainly flows into urban space, followed by agricultural space. According to the division of the first-level ecological space, the main ecological space structure of China is grassland ecological space and woodland ecological space. 2) The spatial distribution characteristics of China’s territorial ecological space are more prominent, and the distribution is very uneven. During the study period, the variation of the standard deviation ellipse angle θ of the ecological space is small, and the migration of the barycenter is not obvious, indicating that China’s territorial ecological space is in a relatively stable state. 3) It is necessary to implement a differentiated policy on the optimization and control of territorial ecological space according to the non-equilibrium of territorial space, and build a unified and coordinated territorial space management and control system. Such a differentiation policy would provide a basis for decision making and a reference for formulating strategies for the sustainable development of the regional ecological environment and optimizing the spatial layout of the territory.

The rapid population growth around the world has become one of the main challenges for countries to ensure adequate food supply. To address this difficulty and ensure adequate food production, sustainable land use, in particular sustainable cultivated land (CL) use, can make a great contribution. Sustainable utilization of CL encompasses several aspects such as quantity and quality, but previous studies have focused on increasing food production, while the interrelationships among cultivated land quantity, quality, and grain yield (CLQQGY) have still received less attention. Hence, based on the GlobeLand30 data during 2000–2020, this paper analyzed the changes of CLQQGY in 130 prefecture-level cities in the Yangtze River Economic Belt (YREB) in China and explored whether the current consecutive harvests is sustainable in the future to feed increasing population. The results revealed the areal loss and quality degradation of CL in most cities in the YREB, the total CL area decreased by 31.07 × 104 hm2 and 282.59 × 104 hm2 during 2000–2010 and 2010–2020, respectively, and the CL quality declining trend was presented in 68.46% and 69.23% cities in the YREB during 2000–2010 and 2010–2020, respectively. Even with such acreage and ecological losses, the total grain yield still increased by 3.77% and 9.53% during 2000–2010 and 2010–2020, respectively, continuing the miracle “continuous harvests” of grain yield in this region. This successive increase in food production in the context of decreasing acreage and ecological deterioration of CL depend mainly on the amount of chemical fertilizer usage, the total power of agricultural machinery and rural electricity consumption. However, due to the heavy reliance on a growth model driven by resource inputs, this type of harvest appeared to be unsustainable because of the significant negative effects brought out by overusing resources. With a view to achieving sustainable use of CL and food production, therefore, this paper proposed policies to promote the sustainable use of CL and food supply for supporting the survival of increasing population through the full implementation of administrative regulations and economic measures that focus on the balance among the quantity and quality and food production of CL in the process of agricultural production and CL management.

Coastal farmers earn their living by the sea, and their willingness to pay (WTP) is particularly important for coastal zone ecological protection (CZEP). What are the specific impacts of livelihood capital and distance effect on farmers' WTP for CZEP? And what are the impact paths of these effects? To answer these questions, taking the coastal zone of the Beibu Gulf of China as an example, this paper constructs an index system based on sustainable livelihood theory, carries out research and design combined with the contingent valuation method (CVM), and conducts an empirical study on the relationship between livelihood capital, distance effect and WTP for ecological protection with the help of the entropy method, ordinary least squares (OLS) linear regression model and bootstrap method. The results show that (1) only 56.23% of the respondents have a WTP for CZEP, while 43.77% of the respondents refuse to pay. (2) The scores of each dimension of farmers' livelihood capital are as follows: risk perception (0.635) > natural capital (0.531) > financial capital (0.406) > human capital (0.299) > social capital (0.130) > physical capital (0.110), and farmers' livelihood capital and distance effect have an inverted U-shaped relationship with the WTP for ecological protection. (3) The ecological protection payments of pure farmers, type 1 farmers, type 2 farmers and nonfarmers were 151.83, 112.73, 78.87 and 95.58 RMB/year, respectively, and the influencing factors are heterogeneous. (4) We found that the mediating effects of natural capital, physical capital and financial capital are negative, social capital and risk perception are positive, while the mediating effects of human capital are not significant. Therefore, the government should establish a comprehensive management system that is cross-regional, cross-departmental, coordinated, systematic and efficient across the coastal zone.

Thermal infrared remote sensing has become one of the main technology methods used for urban heat island research. When applying urban land surface temperature inversion of the thermal infrared band, problems with intensity level division arise because the method is subjective. However, this method is one of the few that performs heat island intensity level identification. This paper will build an intensity level identifier for an urban heat island, by using weak supervision and thought-based learning in an improved, restricted Boltzmann machine (RBM) model. The identifier automatically initializes the annotation and optimizes the model parameters sequentially until the target identifier is completed. The algorithm needs very little information about the weak labeling of the target training sample and generates an urban heat island intensity spatial distribution map. This study can provide reliable decision-making support for urban ecological planning and effective protection of urban ecological security. The experimental results showed the following: (1) The heat island effect in Wuhan is existent and intense. Heat island areas are widely distributed. The largest heat island area is in Wuhan, followed by the sub-green island. The total area encompassed by heat island and strong island levels accounts for 54.16% of the land in Wuhan. (2) Partially based on improved RBM identification, this method meets the research demands of determining the spatial distribution characteristics of the internal heat island effect; its identification accuracy is superior to that of comparable methods.