Earthworms are known to play an important role in improving soil, decomposing agricultural litter, and enhancing soil fertility and crop yield. The acute toxicity of 17 herbicides to Eisenia fetida was determined by a contact filter paper toxicity bioassay and an artificial soil toxicity bioassay. Results of 48 h by the contact filter paper toxicity bioassay, metamifop was high toxicity to E. fetida with LC50 (median lethal concentration) value of 7.6 μg∙cm-2; pretilachlor, haloxyfop-R-methyl, and bentazone were moderate toxicity to E. fetida with LC50 values of 10.7, 12.7, and 61.3 μg∙cm-2, respectively; quinclorac, MCPA-Na, topramezone, glufosinate ammonium, nicosulfuron, and bispyribac-sodium were low toxicity to E. fetida with LC50 values of 143.0, 198.2, 211.1, 466.9, 433.7, and 649.2 μg∙cm-2, respectively; pyrazosulfuron-ethyl, penoxsulam, pyribenzoxim, cyhalofop-butyl, fluoroglycofen, pendimethalin, and mesotrione were slight toxicity to E. fetida with LC50 values greater than 1000 μg∙cm-2. Results of 14 d by the artificial soil toxicity bioassay, haloxyfop-R-methyl showed the highest toxicity to E. fetida with LC50 value of 148.9 mg∙kg-1; followed by pretilachlor, MCPA-Na, pendimethalin, and metamifop, the LC50 values were 211.5, 335.0, 342.4, and 345.7 mg∙kg-1, respectively; the other tested herbicides were low toxicity to E. fetida with LC50 values greater than 500 mg∙kg-1. According to the guidelines of environmental safety evaluation for chemical pesticides, the 17 herbicides determined by an artificial soil toxicity bioassay were low toxicity to E. fetida. The results of this study can provide new data information for assessing the ecological risk of herbicides to earthworm, and also provide technical guidance for the safe use of herbicides in agricultural production.
Grassland is the largest terrestrial ecosystem, which possesses extremely important production and ecological functions. Long-term overutilization and climate change, however, have contributed to degradations of grassland ecosystems worldwide. The natural restoration of degraded grasslands takes long time, and manipulating practices could be indispensable to accelerate the restoration. Although grassland ecological restorations have been studied for several decades in China, the phenomenon of degradation-restoration-re-degradation-re-restoration is common, and grassland degradation has not been comprehensively improved due to the ecological functions have not been paid enough attention. Lately, ecological priority and green development are emphasized, and more attention has been paid to grassland protection and ecological restoration. Restoration of degraded grassland ecosystems is a major problem and daunting task to be solved urgently in China. To provide scientific references for the ecological restoration of degraded grasslands, we reviewed the researches of grassland ecological restoration, as well as the main practical and policy measures. Restoration effects, limiting factors and existing shortcomings of different practical measures (no-tillage sowing, rational grazing, artificial pasture establishment, fence enclosure, tillage and fertilization) were also assessed. On these bases, research directions and suggestions for the grassland ecological restoration in the future were put forth: (1) To establish a modern grass husbandry system and management pattern to fundamentally solve the contradiction between grass and livestock is the prime way to tackle the grassland degradation and ecological restoration; (2) To improve the grassland degradation classification and grading system to provide theoretical bases for ecological restoration; (3) To strengthen the development and utilization of native grass germplasms and soil microorganisms to provide material support for ecological restoration; (4) To break through the theoretical and technical bottlenecks to restore the grasslands full of poisonous weeds; (5) To build a region-classification-grade theoretical and technical system and evaluation system of ecological restoration. Grassland ecological restoration is a complicated, transdisciplinary and systematic engineering, and the key is to strengthen multi-field cooperation.
Farmland is fundamental to grain production. Recently, as the grain output increased year by year, resources and environment faced with multiple challenges. The farmland is high-intensity used, seriously overdrawn, deteriorated, and polluted, which severely restrict the agricultural sustainable development in China. It is a specific way to realize the implementation of a food crop production strategy based on farmland management and the application of technology by carrying out farmland rotation and fallow system to expand overall farmland production capacity, which has a strategic significance on promoting the development of green agriculture and guaranteeing national food security. This paper analyses the advancements and practices on farmland rotation and fallow system in and abroad, and put forward the research priorities and objectives on exploring pilot program of farmland rotation and fallow system. Including investigating farmland resources and regionalization suitable for rotation and fallow in key areas, discussing technological approaches to implement farmland rotation and fallow system in key areas, and establishing systems and mechanisms for exploring pilot program of farmland rotation and fallow system. All is to provide consultation for realizing agricultural transition in the 13th Five-Year Plan and assuring grain production capacity and national food security.
The ecological security pattern is the basis for ensuring regional ecological security and an important means for human beings to maintain green, healthy, and sustainable development. Under the background of increasingly prominent global ecological problems, the ecological security pattern has become a hot area of ecosystem research. Strengthening the study of ecological security pattern is of great significance for maintaining the integrity of the ecosystem structure and function, protecting biodiversity, ensuring regional ecological security, and improving human well-being. Based on “conceptual analyses, fundamental framework, research progress and prospects”, this article comprehensively and systematically reviewed research results on ecological security patterns at home and abroad. The following conclusions were drawn after summarizing the research methods, scales, and contents in the literature: (1) The basic research framework of "source identification-resistance surface construction-corridor extraction" needs to be developed; (2) the identification of ecological source areas lacks a unified scientific standard, and the relationship between supply and demand of ecosystem services has not been considered; (3) the extraction method of ecological corridor needs to be further optimized; (4) there is a lack of consideration of the interrelationship between geospatial linkage and ecosystem functions; (5) The research on the coupling relationship between natural ecosystems and socio-economic systems is relatively weak. Future research may focus on the following aspects: (1) integrated research of multi-model, multi-method, and multi-technology; (2) quantitative research on dynamic consideration of ecological safety standards; (3) realistic implementation research of the game of interests of all parties; (4) research on ecological security prediction, early warning, and regulation management; (5) research on the construction of ecological security patterns serving national strategies.
Net primary productivity (NPP) is the basis for characterizing the material and energy cycle of the ecosystem, which is one of the important components of regional and global carbon cycle. In order to reveal the spatiotemporal change characteristics and driving mechanism of NPP in China from 2001 to 2020, based on MOD17A3HGF data products, the spatiotemporal change and future development trend of NPP in China were analyzed by Sen trend analysis, Mann-Kendall significance test and Hurst index. The relative roles of climate change and human activities in the process of NPP change were quantitatively analyzed by using correlation and residual analysis methods. The results showed that (1) China’s NPP presented a spatial distribution pattern of high in the southeast and low in the northwest, showing a fluctuating upward trend in time, with an upward rate of 2.86 g·m-2·a-1. The spatial change remained unchanged. The area with a significant increase in NPP was significantly larger than the area with a significant decrease. In the future, 84.38% of China's regional NPP will continue to increase or change from a decreasing to an increasing trend. (2) NPP was positively correlated with precipitation and temperature as a whole, of which precipitation had a more significant impact on NPP. The areas with significant positive correlations between NPP and precipitation were mainly distributed in the north of the Yangtze River. The areas with significant positive correlations with temperature were mainly distributed in the central and north of the Qinghai Tibet Plateau, the southeast of the Yunnan Guizhou Plateau, the southeast coastal area and the south of Shandong. (3) Both climate change and human activities played an important role in the NPP improvement areas, but there were significant spatial differences in their relative roles in NPP improvement areas. The vegetation improvement areas dominated by climate change were mainly concentrated in the northeast, north China, Sichuan Basin and the middle and lower reaches of the Yangtze River plain, while the vegetation improvement areas dominated by human activities were mainly concentrated in central, southwest and northwest China. The impacts of climate change and human activities on vegetation degradation were relatively consistent in spatial distribution. The impacts of climate change on NPP degradation areas were slight, but human activities were the main factors causing NPP degradation.
Microplastics are widely detected in the environment, and microplastics entering the environment generally undergo slow and complex aging processes, affecting their interaction with other pollutants in the environment. In this paper, the aging methods, physical and chemical properties of aged microplastics, pollutant adsorption capacity and interaction mechanism were summarized. There are many aging methods for microplastics, mainly involving physical, chemical and biological methods, and different methods have their own characteristics and applicability. The microplastic surface would become rougher after aging, which results in the increase of the surface area. Meanwhile, ultraviolet and natural aging could increase the oxygen-containing functional groups on the surface and promote its adsorption to other pollutants by hydrophobic action, electrostatic action, complexation, hydrogen bond, van der Waals’ force, and π-π interaction. In view of the shortcomings of the aging of microplastics and their interaction with pollutants, some suggestions were proposed to provide support for microplastic aging and its environmental impacts research, such as microplastic aging under complex conditions and its influence on pollutants adsorption, adsorption mechanism of aged microplastic on heavy metal-organic composite pollution, aging of microplastics in living organisms and its biological toxicity, the release of plastics additives during the process of microplastics aging and its interaction with pollutants and that of aged microplastics with dissolved organic matter and minerals.
In order to solve the hardness problem of Leguminosae seeds, two pioneer plants for mine ecological restoration, Crotalaria pallida Ait. and Cassia surattensis Burm. F. were chosen for experimental materials. The seeds were soaked in 200 mg·L-1 gibberellin and distilled water for 12, 24, and 36 h, respectively, to study the effects of gibberellin soaking on the germination of the tested seeds and seedling growth. The results showed that (1) with 200 mg·L-1 Gibberellin soaking for 12 h, the germination rate of C. pallida was significantly higher than that in CK and distilled water seed soaking treatment. However, with more soaking time, the effects of promoting germination were not obvious, and Gibberellin soaking for 36 h could improve the seed vitality and other indices. (2) Both Gibberellin and distilled water soaking could promote seed germination rates of C. surattensis. The best seed soaking time of Gibberellin was 24 h, and the germination rate was significantly higher than that in CK and distilled water soaking treatment. The effects of germination promoting were decreased with soaking time. (3) The seed soaking with Gibberellin could not promote the biomass indices of C. pallida obviously, while the high concentration of Gibberellin should inhibit the seedling growth. (4) The seed soaking with Gibberellin could promote the biomass indices of C. surattensis, e.g., the seedling length and root length were improved under Gibberellin soaking for 24 h. In summary, the seed hardness of two test plants could be broken by Gibberellin soaking for an appropriate period of time. The reagent, concentration and soaking time should all be considered in terms of economic and time costs in ecological restoration of mining area.
