Urban agriculture has been proposed as an important urban element to deal with the challenges of food insecurity and environmental deterioration. In order to track current popular topics and global research trends in urban agriculture, we used bibliometric analysis and visualization mapping to evaluate and analyze the developments in the knowledge of urban agriculture based on 605 papers from the core collection database Web of Science from 2001–2021. The results were as follows. (1) The number of urban agriculture publications increased substantially year by year, indicating that the field is attracting increasing attention. The University of Kassel, Chinese Academy of Sciences, and University of Freiburg are the most productive research institutions in the field of urban agriculture. The top-five most influential countries are the Unites States, Germany, the United Kingdom, Italy, and China, of which the Unites States plays a central role in the cooperative linkage between countries. (2) Research on urban agriculture focuses not only on food production and different styles but also on how to realize the various functions of urban agriculture. In addition, UA-related sustainability and the water-energy-food nexus have become two emerging research topics. (3) Urban agriculture does not necessarily mean a resource-conserving and environmentally friendly food system. To achieve sustainable development, a transition based on technological innovation is needed. How to improve the sustainable development level of the food system while fully considering the resilience, sustainability, and versatility of urban agriculture is the main direction of future research.

With the rapid development of China’s new energy vehicle industry, the supply security of lithium resources is crucial. To ensure the healthy development of the new energy vehicle industry and the security of supply of key mineral resources, it is necessary to accurately determine the supply and demand pressure of lithium resources and their sources. This study analyzes the lithium stock and flow at the end of the new energy vehicle chain by constructing a material flow analysis framework for the new energy vehicle industry and compiling a lithium resource flow table for the new energy vehicle industry, and the results show that 1) the supply and demand pressure on lithium resources in China is increasing year by year, and the external dependence of lithium resources has reached 75% in 2019; 2) China’s domestic lithium battery production and consumption accounted for nearly 70% of the lithium consumption in various industries, of which 60% of the lithium batteries were assembled on new energy vehicles, and the net outflow of lithium exceeded more than the lithium consumption of new energy vehicles in 2019. The lithium consumption of new energy vehicles was more than five times that of the previous year. Insufficient supply of domestic lithium ore, lithium inventory, and import and export are the key reasons for the pressure on lithium supply and demand in the new energy vehicle industry; 3) By the end of 2019, the cumulative scrap lithium batteries in new energy vehicles contain about 10,000 tons. The lithium accumulated in new energy vehicles has 26,500 tons. These results provide a theoretical basis for policy recommendations to ensure the healthy development of the new energy vehicle industry and to promote international cooperation in the development, utilization, and recycling of lithium resources.

The reform of water management in China is still in progress, and the pricing of water resources is undertaken in parallel, with a divide between irrigation water and pipe water associated with different users: The supply of irrigation water is regulated by local government and that of pipe water is operated by the production sector of pipe water. Based on a literature review and an interview survey of farmers, this study incorporated the water parallel pricing system of China within a computable general equilibrium (CGE) model, where the drought of 2000 is simulated. The 16 provincial irrigation water supplies and their subsidies were also estimated and introduced into this CGE model. The results demonstrated that the effects on the macro-economy were insignificant. However, the effects on agricultural production, particularly on farming production mainly cultivated in northern areas, were significant. Most farming production sectors employed more capital and labor to prevent losses in output from drought. Agricultural labor was shifted from non-farming agricultural production sectors into farming. Both urban and rural households suffered severe losses in welfare and food consumption, even though they benefited from the additional income. Moreover, rural households suffering the worst losses were located in both northern and southern areas.

Summary: Environmental stressors, especially low temperature, are very common on the earth's dryland systems. Terrestrial cyanobacteria have evolved with cold adaptability in addition to extreme dryness and high irradiation resistance. The dryland soil surface‐dwelling species, Nostoc flagelliforme , serves as a potential model organism to gain insights into cyanobacterial cold adaptation. In this study, we performed transcriptomic analysis of N . flagelliforme samples in response to low temperature. The results revealed that the biological processes, such as terpenoid biosynthetic process, oxidoreductase activity, carbohydrate metabolism, biosynthesis of secondary metabolites, lipid and nitrogen metabolism, were significantly and dynamically changed during the cold stress. It was noteworthy that the transcription of the denitrification pathway for ammonia accumulation was enhanced, implying an importance for nitrogen utilization in stress resistance. In addition, characterization of a cold‐responsive hypothetical gene csrnf1 found that it could greatly improve the cold‐resistant performance of cells when it was heterologously expressed in transgenic Nostoc sp. PCC 7120. It was also found that csrnf1 transgenic strain exhibited resistance to nitrogen‐deficient environmental stress. Considering that dryland cyanobacteria have to cope with low temperature on infertile soils, this study would enrich our understanding on the importance of multifunction of the genes for environmental cold adaptation in drylands.

Coastal cities have been experiencing tremendous land use changes worldwide. Studies on the consequences of land use change in coastal cities have provided helpful information for spatial regulations and have attracted increased attention. Changes in forests and water bodies, however, have rarely been investigated, challenging the formation of a holistic pattern of land use change. In this study, we selected Ningbo, China, as a case study area and analyzed its land use change from 1990 to 2016. Random forest (RF) classification was employed to derive land use information from Landsat images. Transition matrices and a distribution index (DI) were applied to identify the major types of land use transitions and their spatial variations by site-specific attributes. The results showed that the entire time period could be divided into two stages, based on the manifestations of land use change in Ningbo: 1990–2005 and 2005–2016. During 1990–2005, construction land expanded rapidly, mainly through the occupation of agricultural land and forest, while during 2005–2016, the main change trajectory turned out to be a small net change in construction land and a net increase in agricultural land sourced from construction land, forests, and water bodies. In terms of land use change by site-specific attributes, the rapid expansion of construction land around the municipal city center during 1990–2005 was restrained, and similar amounts of land conversion between construction and agricultural use occurred during 2005–2016. During the study period, areas undergoing land use change also showed trends of moving outward from the municipal city center and the county centers located adjacent to roads and the coastline and of moving up to hilly areas with steeper slopes and higher elevations. Protecting reclaimed agricultural land, improving the efficiency of construction land, and controlling forest conversion in hilly areas are suggested as spatial regulations in Ningbo city.