Storing Grain in the Land: The Gestation, Delineation Framework, and Case of the Two Zones Policy in China

Cultivated land (CL) protection is an overarching strategic concern for stabilizing the agricultural foundation and for achieving the sustainable development of the national economy and society. Faced with the challenges of the dual drives of complex domestic and international situations, China’s CL protection system has coupled the quantity and quality dimensions and focused on a dynamic balancing system and permanent basic farmland (PBF) policy. However, it has had difficulty meeting the objectives of sustainable agricultural development and is undergoing upgrades. Accordingly, the Chinese government has issued a CL protection policy that includes adjusting the planting structure, optimizing the agricultural layout, and adding the three dimensions of quantity, quality, and planting structure, namely “Delimitation of the Grain Production Functional Zone and the Important Agricultural Product Production-Protection Zone” (the “two zones” policy). With regard to the ambiguous understanding of the two zones policy, this study aims to explore the following issues: (1) How was the two zones policy conceived? (2) What mechanism does it use to make up for the deficiencies of the previous policy? (3) How does it integrate the three dimensions of quantity, quality, and planting structure? (4) How to reasonably delimit the two zones. To solve these problems, this paper first reviews the evolution of China’s CL protection policies and explains the incubation process of the two zones policy and its connotation and mechanism. Then, a delineation framework process is proposed and the approaches of executing the two zones policy on a regional scale are discussed. Furthermore, a real delimitation was conducted in Qianguo County to validate the framework. The evidence shows that customizing CL use according to regional resource potential differentiation and forming a CL protection policy with the three dimensions of quantity, quality, and structure are effective in improving the productive potential of CL and promoting the adjustment of the planting structure. Furthermore, the framework and case study findings of the delimitation provide a theoretical reference and practical foundation to translate macro policy into micro management

Coupling or contradiction? The spatiotemporal relationship between urbanization and urban park system development in China

The urban park system (UPS) is an essential determinant of a city’s vitality and construction quality, playing an important role in the process of the high-quality construction of new urbanization. To explore the coupling and coordination relationship between UPSs and urbanization, a multidimensional evaluation system for urbanization and UPSs is constructed for 30 provinces in China from 2000 to 2020, and the indexes are calculated using the entropy weight method. Then, a coupling coordination degree (CCD) model and relative development degree (RDD) model are used to comprehensively analyze the spatiotemporal evolutionary pattern in the coupling coordination between systems from a systematic perspective to a holistic perspective. On this basis, the spatial clustering of the CCD is identified by spatial autocorrelation methods. The research results indicate the following: (1) The urbanization indexes and UPS index both improved over the research period and both exhibit a significantly higher index in eastern provinces than in other regions. (2) The CCD between systems generally improved to a higher level overall. The spatiotemporal patterns indicate that the CCD showed a trend of deepening development from the edge to the middle. (3) Regarding the RDD, there was a widespread lack of synergy between UPSs and urbanization systems. In 2020, most provinces showed that the development of UPSs lagged behind urbanization. (4) The cold and hot spots of spatial clustering revealed a spatial evolution and migration trend, albeit to a limited extent. The cold spots were always distributed in the west with a gradually shrinking scope, while the hot spots were concentrated in the east, with their scope gradually expanding

Spatiotemporal dynamics of urban green space in Changchun: Changes, transformations, landscape patterns, and drivers

To better understand the phased changes, development direction and planning challenges of urban green space (UGS) in response to the urbanization process and changing urban development goals, this study examines the spatiotemporal variations, landscape patterns and driving forces of UGSs in Changchun from 1990 to 2020. The results indicate that the evolution of UGSs may be largely categorized into three stages, considerable decline, balance between increase and decrease, and surge increase, accompanied by obvious changes to the landscape. Several factors have contributed to these changes, including natural, urbanization and changing greening policies. Early urbanization resulted in the encroachment and fragmentation of a considerable amount of UGS; however, as urban building priorities have changed, UGS planning has increasingly gained attention. In the third decade of the research period, UGSs greatly expanded, demonstrating some achievements in the construction of UGSs under the background of ecological civilization. Knowledge of the dynamics of UGSs provides a reference for urban greening planning, which also helps cities respond to the call for land “ecological use, ecological security and green development” during the urbanization process in China and similar countries

Enhanced Lubricant Property of Flame-Sprayed Aluminum Coatings Additivated by Reduced Graphene Oxide Nanosheets

Enhanced Lubricant Property of Flame-Sprayed Aluminum Coatings Additivated by Reduced Graphene Oxide Nanosheet

Aluminum-polyethylene composite coatings with self-sealing induced anti -corrosion performances

Aluminum (Al) based coatings fabricated using arc spraying are usually employed as anti-corrosion coatings in the marine environment, coupled with post-treated sealing on their surfaces. In this investigation, ultra-high molecular weight polyethylene (UHMWPE) particles were added in Al coatings using cored wire arc spraying, in which UHMWPE were employed as sealants, instead of post-sealing treatment. The microstructures of in-flight particles and singly deposited particles were characterized to reveal microstructure evolution mechanisms of cored wires. The microstructures of composite coatings were also analyzed to discuss the self-sealing mechanism of UHMWPE particles. Neutral salt spraying and electrochemical analysis were employed to reveal corrosion thermodynamics and kinetics of composite coatings. The results show that UHMWPE particles presented two structures in composite coatings. The melted UHMWPE thin films sited at the interfaces of Al particles, played as sealants, contributing to the increase of corrosion resistance. Incompletely melted UHMWPE particles also existed in composite coatings, due to the protective effect of Al-UHMWPE core-shell structures formed in spraying. The strategy fabricating Al-UHMWPE composite coatings gives bright insight into a new route to develop marine self-sealing induced anti-corrosion coatings

Asynchronous responses of soil microbial community and understory plant community to simulated nitrogen deposition in a subtropical forest

Atmospheric nitrogen (N) deposition greatly affects ecosystem processes and properties. However, few studies have simultaneously examined the responses of both the above- and belowground communities to N deposition. Here, we investigated the effects of 8 years of simulated N deposition on soil microbial communities and plant diversity in a subtropical forest. The quantities of experimental N added (g of N m(−2) year(−1)) and treatment codes were 0 (N0, control), 6 (N1), 12 (N2), and 24 (N3). Phospholipid fatty acids (PLFAs) analysis was used to characterize the soil microbial community while plant diversity and coverage were determined in the permanent field plots. Microbial abundance was reduced by the N3 treatment, and plant species richness and coverage were reduced by both N2 and N3 treatments. Declines in plant species richness were associated with decreased abundance of arbuscular mycorrhizal fungi, increased bacterial stress index, and reduced soil pH. The plasticity of soil microbial community would be more related to the different responses among treatments when compared with plant community. These results indicate that long-term N deposition has greater effects on the understory plant community than on the soil microbial community and different conservation strategies should be considered

Fabrication of TiO2-SrCO3 Composite Coatings by Suspension Plasma Spraying: Microstructure and Enhanced Visible Light Photocatalytic Performances

A novel TiO2-SrCO3 co-catalyst with a porous structure was fabricated by suspension plasma spraying. SrTiO3 as revealed by high-resolution TEM was formed by the chemical reaction of TiO2 with SrCO3 during the high-temperature plasma spraying. A narrow band gap (2.58 eV) and reduction in the recombination speed of photoinduced carriers of the coatings were detected by UV-visible diffuse reflectance spectrometry and fluorescence spectrometry, respectively. The enhanced visible light-driven photodegradation properties of the coatings resulted in promoted degradation of methylene blue. The composite coatings also demonstrated significantly pronounced bactericidal activities against the Gram-negative bacterium Escherichia coli than the pure TiO2 coatings, achieving a killing rate of over 99.7%. The results give insights on the potential to fabricate large-scale nano-TiO2-based porous photocatalytic coatings by suspension plasma spraying for versatile environmental applications. [GRAPHICS]

Asynchronous responses of soil microbial community and understory plant community to simulated nitrogen deposition in a subtropical forest

Atmospheric nitrogen (N) deposition greatly affects ecosystem processes and properties. However, few studies have simultaneously examined the responses of both the above- and belowground communities to N deposition. Here, we investigated the effects of 8 years of simulated N deposition on soil microbial communities and plant diversity in a subtropical forest. The quantities of experimental N added (g of N m-2 year-1) and treatment codes were 0 (N0, control), 6 (N1), 12 (N2), and 24 (N3). Phospholipid fatty acids (PLFAs) analysis was used to characterize the soil microbial community while plant diversity and coverage were determined in the permanent field plots. Microbial abundance was reduced by the N3 treatment, and plant species richness and coverage were reduced by both N2 and N3 treatments. Declines in plant species richness were associated with decreased abundance of arbuscular mycorrhizal fungi, increased bacterial stress index, and reduced soil pH. The plasticity of soil microbial community would be more related to the different responses among treatments when compared with plant community. These results indicate that long-term N deposition has greater effects on the understory plant community than on the soil microbial community and different conservation strategies should be considered. Nitrogen deposition may change above- and belowground biological communities. Our results indicate that N deposition has greater effects on the understory plant community than on the soil microbial community and different conservation strategies should be considered

Response of soil respiration and ecosystem carbon budget to vegetation removal in Eucalyptus plantations with contrasting ages

Reforested plantations have substantial effects on terrestrial carbon cycling due to their large coverage area. Although understory plants are important components of reforested plantations, their effects on ecosystem carbon dynamics remain unclear. This study was designed to investigate the effects of vegetation removal/understory removal and tree girdling on soil respiration and ecosystem carbon dynamics in Eucalyptus plantations of South China with contrasting ages (2 and 24 years old). We conducted a field manipulation experiment from 2008 to 2009. Understory removal reduced soil respiration in both plantations, whereas tree girdling decreased soil respiration only in the 2-year-old plantations. The net ecosystem production was approximately three times greater in the 2-year-old plantations (13.4 -1 yr -1) than in the 24-year-old plantations (4.2 -1 yr -1). The biomass increase of understory plants was 12.6-1 yr -1 in the 2-year-old plantations and 2.9 -1 yr -1 in the 24-year-old plantations, accounting for 33.9% and 14.1% of the net primary production, respectively. Our findings confirm the ecological importance of understory plants in subtropical plantations based on the 2 years of data. These results also indicate that Eucalyptus plantations in China may be an important carbon sink due to the large plantation area

Effect of cobalt substitution on magnetic properties of Ba4Ni2−xCoxFe36O60 hexaferrite

Co-substituted U-type hexagonal ferrite bulks, with composition of Ba4Ni2−xCoxFe36O60 (x=0.2, 0.4, 0.6, 0.8), were prepared by a conventional ceramic method. Saturation magnetization (4πMs), coercivity (Hc), and Curie temperature (Tc) were investigated. Anisotropy constant (K1) was calculated by fitting the magnetization curve (M-H) according to the law of approach to saturation, and anisotropy field (Ha) was calculated accordingly. The results reveal that all the samples possess the U-type hexagonal crystallographic structure. With increasing cobalt substitution content (x), the lattice parameters (a and c) almost remain the same owing to the similar radii of Ni2+ (0.72 Å) Co2+ (0.74 Å) ions. 4πMs goes up, while Hc Hc shows an opposite trend. K1 and Ha monotonously decrease resulting from that cobalt substitution weakens the c-axis orientation. Additionally, Tc increases from 467 °C to 484 °C