Vegetation restoration is a fundamental method of ecological reconstruction in disturbed areas, and revegetation can be achieved by passive (spontaneous succession) and active (human-induced) approaches. Plant community composition, productivity, and diversity were studied in coal mining subsidence areas after 0–15 years of restoration with active (AR) and passive (PR) revegetation approaches in a semiarid region. Moreover, plant community composition, succession, and their relationships with soil variables were analyzed. The results showed that both PR and AR contributed to the recovery of the plant community in terms of plant cover, density, biomass, and diversity, with AR accelerating the recovery of the plant comm unity to a greater extent than PR. Soil moisture and organic matter had close relationships with the plant community variables. The plant communities in PR sites had the same species composition as those in non-subsidence (NS) areas, which led to a more natural plant community in PR than AR sites. Plant community structure in AR sites was altered by the introduced shrubs, with mesophytes developing under the introduced shrubs. These changes produced a different successional trajectory in AR sites from that in NS sites; thus, environmental fluctuations may easily change AR community stability in semiarid environments.
The comparative analysis of nine routine chemical indexes of flue-cured tobacco, including B2F, C3F and X2F, from ten counties with similar ecological conditions in south Hunan was carried out. The results indicated that: 1) total sugar, reducing sugar, total nitrogen and potassium were at right levels and harmonious chemically, except that total alkaloid was slightly high and chlorine was lower; 2) the concentration difference of chemical components in tobacco samples between cultivars was not great, the difference between counties was not great as well except for chlorine and potassium, while that between stalk positions and grown years was significant.
In recent years, as the concept of sustainable development has grown in popularity, ESG has attracted widespread interest from people of all backgrounds. This paper empirically investigates the impact of corporate ESG performance on bond credit spreads using a sample of 988 bonds issued by 443 A-share listed companies from the first quarter of 2009 to the fourth quarter of 2020. Results indicate that bond credit spreads are lower for listed companies with higher ESG performance. Good ESG performance decreases bond credit spreads by decreasing corporate financial risk, enhancing corporate transparency, and decreasing debt agency costs. The effect of ESG performance on bond credit spreads is more pronounced for non-state enterprises, enterprises in poor macroeconomic environments, and enterprises in regions with a higher degree of marketization. This study provides evidence for the positive economic consequences of ESG performance from the perspective of bond financing, with implications for firms to improve ESG performance and bond investors to optimize investment decisions.
Humans spend most of their time in settlements, and the built environment of settlements may affect the residents' sentiments. Research in this field is interdisciplinary, integrating urban planning and public health. However, it has been limited by the difficulty of quantifying subjective sentiments and the small sample size.
The investigation and analysis of the heavy metal contamination was conducted in several main vegetable bases in the suburb of Changsha region. The results showed that among vegetables produced form vegetable bases of the suburb of Changsha, except leaf vegetables, other vegetables were not contaminated. There were 100% of the samples whose plumbum content exceeded the standard, the most exceeded was 137% higher than the standard and averaged 60% higher than the standard; and 50% of the samples whose cadmium content exceeded the standard. the most exceeded was 127% higher than the standard, whose average cadmium content was closed to the heavy metal index of nuisanceless vegetable in China. The order of enrichment ability to heavy metal in different type of vegetables is leaf vegetablesolanaceous fruit vegetableleguminous vegetablegourd vegetable. The enriching order of heavy of heavy metal is CdHgPbAsCr. The heavy metal contamination in soils of the suburb of Changsha city is much serious. There are Cd contamination in 70% of soil, and Hg contamination in 27.6% of soil,while comprehensive contamination of heavy metal in 58.6% of soil. The related department should take the feasible measures to control the further extended and fast contamination.
By adopting GPS technique, 2088 sampling sites were installed in the tobacco-planting area of Qujing City, Yunnan Province, with 0-20 cm soil samples collected to determine their main nutrients contents. The overall characteristics and spatial variability of the tobacco soil nutrients were analyzed by classic statistics and geo-statistics, and the soil fertility suitability in planting tobacco was evaluated by the methods of fuzzy mathematics. In the study area, soil pH and soil organic matter, available S, and water-soluble Cl contents were appropriate, soil total N and alkalihydrolyzable N contents were too high, soil available K, Ca, Mg, Cu, Fe, Zn, Mo, and Mn contents were abundant, soil available P content was at medium level, while soil total P and K and available B contents were insufficient. All the nutrient indices presented anisotropic distribution, among which, the spatial variability of soil available P and B was mainly caused by random factors, and that of other nutrients was caused by the co-effects of structural and random factors. The spatial distribution map of soil fertility suitability index (SFI) showed that there was no the excellent grade region for tobacco-planting, good grade region accounted for 8.0%, general grade region accounted for 51.6%, moderate grade region accounted for 39.0%, and low grade region accounted for 1.4%.
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