Higher biodiversity is often assumed to be a more desirable scenario for maintaining the functioning of ecosystems, but whether species-richer communities are also more disturbance-tolerant remains controversial. In this study, we investigated the bacterial communities based on 472 soil samples from 28 forests across China with associated edaphic and climatic properties. We developed two indexes (i.e., community mean tolerance breadth [CMTB] and community mean response asynchrony [CMRA]) to explore the relationship between diversity and community resistance potential. Moreover, we examined this resistance potential along the climatic and latitudinal gradients. We revealed that CMTB was significantly and negatively related to species richness, resulting from the changes in balance between relative abundances of putative specialists and generalists. In comparison, we found a unimodal relationship between CMRA and richness, suggesting that higher biodiversity might not always lead to higher community resistance. Moreover, our results showed differential local patterns along latitude. In particular, local patterns in the northern region mainly followed general relationships rather than those for the southern forests, which may be attributed to the differences in annual means and annual variations of climate conditions. Our findings highlight that the community resistance potential depends on the composition of diverse species with differential environmental tolerance and responses. This study provides a new, testable evaluation by considering tolerance breadth and response asynchrony at the community level, which will be helpful in assessing the influence of disturbance under rapid shifts in biodiversity and species composition as a result of global environmental change.

Expressway construction has caused a significant threat to the ecological environment in developing countries, and therefore the variation characteristics of ecological resilience along the expressway in developing countries are of major importance. This empirical study focuses on a typical area within a 2-km range of the Phnom Penh-Sihanoukville Expressway in Cambodia and uses remote sensing and geographic information systems (GIS) technology to analyze the variation characteristics of ecological resilience along the expressway. The results of the study reveal that due to the construction of expressways, the land use types transferred into or out of the land use types increase and furthermore the land use types show a trend of decreasing natural attributes and increasing human attributes. It is found that expressway construction has an observed effect on the transfer rate of the center of gravity of land use type, and the direction of the center of gravity shifts in the direction of expressway construction. The impact of construction on the ecological resilience of the western region with higher vegetation coverage was higher than that of the eastern region with higher urbanization. The research develops a theoretical evaluation model based on land use type of the variation characteristics of ecological resilience along the expressway, which can be used to enable the sustainability of expressway construction and maintain the regional ecological environment.

How to combine regional ecological risks and local ecological needs to construct ecological security is one of the main issues of its application in territorial spatial governance and associated with whether it can be effectively applied. Based on the \"source\" accessibility and the quality of space, we constructed the ecological security pattern of Xianyang City through the way of source-corridor-node. During the construction processes, we combined the cha-racteristics of topography, influencing factors of regional ecological security, and landscape characteristics. We coupled them with morphological spatial pattern analysis (MSPA) and comprehensive evaluation results of ecological resistance, ecological connectivity and ecosystem service value, and superimposed with ecological gradient ana-lysis. The results showed that there were 66 ecological sources, with a total area of 2506.65 km2, accounting for 24.6% of the total area of Xianyang City, which were mainly distributed in the northeast, west and central mountainous areas. There were 106 ecological corridors with a total length of 823.5 km, including potential corridors, water systems, irrigation canal sites, Qinzhidao and other natural and cultural systems, which extended along the ecological source to the northwest and south Weihe River. There were 20 ecological nodes to improve ecological connectivity, which were mainly distributed between second layers of loess tableland and arid mountainous areas with banded distribution in the north part of the city.
生态安全格局如何结合地域生态风险和地方生态需求进行构建,是该领域服务于国土空间治理并且能否有效应用的主要议题之一。本研究以咸阳市为对象,结合市域地貌形态、地域生态安全影响因素和景观特征,基于“源地”空间可达性和空间质量,融合形态学空间格局分析和生态抗性、生态连通性、生态系统服务价值综合评价结果,叠加生态梯度分析,以源地-廊道-节点的方式构建生态安全格局。结果表明: 咸阳市生态源地66个,总面积2506.65 km2,约占全市总面积的24.6%,主要分布于东北、西侧、中部山区;生态廊道106条,总长823.5 km,包括潜在廊道、水系、灌渠遗址、秦直道等自然与人文系统,沿生态源地向西北、南部渭河延伸;提升生态连通性的生态节点20处,主要分布于二道塬与旱腰带之间。.

With ongoing economic and social development, natural habitats are becoming increasingly fragmented, blocking habitat connections and reducing landscape connectivity. The study of changes in ecological connectivity can provide valuable information for habitat and landscape restoration, which are necessary for sustainable regional development. Despite the growing interest in this issue, studies that reveal the change in ecological connectivity in the compounded areas of ecological vulnerability and deep poverty are still lacking. In this paper, one of the most underdeveloped and ecologically fragile southwestern ethnic regions of China, the Sanzhou region of Sichuan Province, was the study area. Based on a vector map of current land-use status and vector data on ecosystem factors and nature reserves in 2010 and 2015, the change in ecological connectivity was analyzed using the minimum cumulative resistance model using GIS spatial analysis method. Firstly, ecological sources were identified based on the distribution of ecological functional areas. Secondly, the ecological resistance surface based on ecosystem service value is revised by integrating the three dimensions of topography and hydrology, ecological environment and development, and utilization intensity. Finally, the ecological connectivity of ethnic areas in southwest China in 2010 and 2015 was compared and analyzed through the perspective of ecological resistance. The results show that: (1) From 2010 to 2015, the overall ecological connectivity decreased. (2) There were six areas of high ecological resistance featuring human activity and ecological degradation: the Anning River Valley in Liangshan Prefecture, Ganzi, Dege and Luho counties in Ganzi Prefecture, and Ruoergai and Hongyuan counties in Aba Prefecture. (3) Low ecological resistance areas were more numerous and widely distributed, forming an ecological protection barrier for the three autonomous prefectures, and regulating and protecting their natural environments. It is necessary to maintain and strengthen this protection; accordingly, measures are proposed to improve ecological connectivity. This study provides a reference for achieving ecological security and harmonious coexistence between humans and nature in this region.

Long-term continuous cropping of soybean can generate the development of disease-suppressive soils. However, whether the changes in microbial communities, especially for archaea, contribute to controlling soil sickness and improving crop yields remains poorly understood. Here, real-time PCR and high-throughput sequencing were employed to investigate the changes in soil archaeal communities in both bulk and rhizosphere soils under four cropping systems, including the continuous cropping of soybeans for a short-term of 3 and 5 years (CC3 and CC5, respectively) and for a long-term of 13 years (CC13), as well as a soybean-maize rotation for 5 years (CR5). The results showed that CC13 and CR5 significantly increased archaeal abundance, reduced the alpha-diversity of archaeal communities, and changed soil archaeal community structures compared to CC3 and CC5. Microbial co-occurrence network analysis revealed that CC13 led to the higher resistant microbial community and lower the relative abundance of potential plant pathogens in the network compared to CC3 and CC5. Correlation analysis showed that the microbial resistance index was negatively correlated with the relative abundance of potential plant pathogens and positively correlated with soybean yields in both bulk and rhizosphere soils. Intriguingly, the random forest (RF) analysis showed that archaea contributed the most to soil microbial resistance even though they were not at the core positions of the network. Overall, structural equation models (SEMs) revealed that high resistant microbial community could directly or indirectly improved soybean yields by regulating the relative abundance of plant pathogens and the soil nutrients, suggesting that the regulation of soil microbial taxa may play an important role in maintaining agricultural productivity under continuous cropping of soybean.

Genetically engineered (GE) rice lines expressing Lepidoptera-active insecticidal cry genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China. Field surveys indicated that Bt rice harbours fewer rice planthoppers than non-Bt rice although planthoppers are not sensitive to the produced Bt Cry proteins. The mechanisms underlying this phenomenon remain unknown. Here, we show that the low numbers of planthoppers on Bt rice are associated with reduced caterpillar damage. In laboratory and field-cage experiments, the rice planthopper Nilapavata lugens had no feeding preference for undamaged Bt or non-Bt plants but exhibited a strong preference for caterpillar-damaged plants whether Bt or non-Bt. Under open-field conditions, rice planthoppers were more abundant on caterpillar-damaged non-Bt rice than on neighbouring healthy Bt rice. GC-MS analyses showed that caterpillar damage induced the release of rice plant volatiles known to be attractive to planthoppers, and metabolome analyses revealed increased amino acid contents and reduced sterol contents known to benefit planthopper development. That Lepidoptera-resistant Bt rice is less attractive to this important nontarget pest in the field is therefore a first example of ecological resistance of Bt plants to nontarget pests. Our findings suggest that non-Bt rice refuges established for delaying the development of Bt resistance may also act as a trap crop for N. lugens and possibly other planthoppers.