生物多样性控制作物病害研究进展

自然资源的合理利用和生态环境保护是人类实现可持续发展的基础, 生物多样性的研究和保护已成为世界各国普遍关注的重大问题。农作物病害是农业生产上重要的生物灾害, 是制约农业可持续发展的主要因素之一, 抗病品种大面积单一化种植导致了农业生物多样性水平严重降低, 因而农业生物多样性的过度丧失已成为可持续农业所面临的主要难题。利用生物多样性持续控制作物病害能减轻作物病害发生和作物产量损失, 达到保护作物多样性, 减少农药过量施用给农业生态环境造成破坏的最终目的, 而揭示生物多样性控制作物病害的机制能有效地指导生产上对不同作物进行合理布局和轮换, 建立作物不同组合的优化搭配和种植模式。文章从分子、生理和生态水平研究农业生物多样性控制作物病害的机制、以及影响作物多样性控制病害的因素、覆盖作物等几方面对生物多样性控制作物病害的研究进展进行概述, 同时对今后生物多样性控制作物病害机制还需加强的研究部分进行了展望。     

黑河中游干旱绿洲土壤盐渍化对大型土壤动物群落的影响

以内陆干旱区黑河中游绿洲边缘区天然沙质草地及其转变的人工梭梭灌木林（21 a）、人工杨树林（28 a）、人工樟子松林（33 a）和农田（开垦27 a和100 a）为研究对象,对6种样地土壤盐渍化和大型土壤动物群落特征进行调查,采用多变量排序、多元回归和通径分析及一元回归分析等方法,研究了不同土地覆被和管理措施下土壤动物群落组成及对土壤盐碱环境变化的响应.结果表明: 在缺乏管理措施的情况下,单纯改变土地覆被并不会显著影响土壤动物群落结构;而在有管理措施的情况下,土地覆被变化与管理措施耦合可显著改变土壤动物群落结构.土壤动物群落演变受到土壤pH、可溶性盐及Na⁺、Cl^-、HCO₃^-、Mg²⁺浓度的共同影响,其中Na⁺和可溶性盐含量的贡献率最大,是关键影响因子.土壤动物密度和类群丰富度与土壤中的Na⁺和可溶性盐含量呈显著负指数函数关系,与Mg²⁺和HCO₃^-含量呈显著二次曲线关系.研究区土壤动物密度和类群丰富度在Mg²⁺和HCO₃^-含量达到生态阈值点（分别为38.7～39.4 mg·kg^-1和324.9～335.3 mg·kg^-1）时达到峰值（40～43只·m^-2和13～14科·m^-2）.此后,随着Mg²⁺和HCO₃^-含量的增加, 土壤动物密度和类群丰富度下降.     

我国珍稀濒危植物保护红线的划定

本文依据《国家生态保护红线——生态功能基线划定技术指南(试行)》原则和植物保护的具体情况, 探讨了我国珍稀濒危植物保护红线划定的原则与方法。研究选取《国家重点保护野生植物名录》中收录的所有物种作为研究对象。将其定义为红线保护植物, 其中的I级保护植物定义为红线关键植物, 并基于文献资料及标本记录等数据建立了我国植物的属性数据库和地理分布数据库。在GIS支持下, 以建立的数据库为基础研究了我国红线保护植物的地理分布特征; 基于保护生物学理论, 结合我国自然保护区的就地保护现状进行了分析和评价; 以热点地区和GAP分析为理论基础, 在其分布地中识别具有代表性的热点区域以及不同属性植物分布的重点区域, 进而结合土地利用和人类干扰因素, 划定我国珍稀濒危植物生境整体保护的红线。通过在全国尺度上的分析, 得出我国珍稀濒危植物的整体保护红线面积为71.63万km², 占陆域国土面积的7.45%。植物生境保护红线划定的原则、方法和划定方案的研究对于更准确地划定生态安全预警红线具有重要意义, 同时可以为我国国土生态安全格局的构建提供依据。     

国外生态保护地体系对我国生态保护红线划定与管理的启示

中国共产党第十八届三中全会和《环境保护法》明确提出依法划定生态保护红线, 实施最为严格的源头保护制度。世界上大多数国家都实行了将天然或近天然的区域划作保护地、建立生态空间体系对物种及其生境进行保护。在国际上虽未有“生态保护红线”这一提法, 但是划定生态保护区域的做法是相似的。作者基于相关文献, 对世界自然保护联盟(IUCN)保护地系统, 以及美国、欧盟、俄罗斯、日本等地区和国家的生态保护地(区)体系的保护地面积和管理实践进行了系统梳理和总结。大多数国家的生态保护地(区)的面积在5-40%之间, 并建立了专门的保护管理职能部门或成立了多部门分工负责的管理体制, 根据人类活动强度的不同制定差异化的管控措施。对比我国现有保护地体系的空缺分析以及保护地分类管理中存在的问题, 本文提出了整合与优化我国现有各类保护区域, 通过重要性、敏感性评价对在生态系统服务功能、生物多样性和生境保护方面作用最为重要的土地优先划入生态保护红线内, 面积比例以占到陆地国土总面积的30%以上为宜。为严守生态保护红线, 根据我国现有部门职能分工, 建议强化环境保护部门对生态保护红线区域的统一监督管理职能, 制定生态保护红线管理办法, 在生态保护红线区域内实行分级分类管理。     

哀牢山中山湿性常绿阔叶林两种优势幼苗C、N、P化学计量特征及其对N沉降增加的响应

N沉降对不同森林生态系统的影响是当今全球变化生态学研究的一个热点问题。山地湿性常绿阔叶林是我国西部高海拔地区重要的森林植被类型之一。该文以云南哀牢山中山湿性常绿阔叶林为对象, 研究了其林下优势树种多花山矾(Symplocos ramosissima)和黄心树(Machilus gamblei)幼苗不同器官中C、N、P含量和生态化学计量特征及其对N沉降增加的响应。结果表明: 两种幼苗C、N、P含量的差异均达到了显著性水平(p < 0.05), 多花山矾的C含量较低, N和P含量较高。N处理对植物幼苗元素含量及其比值影响极显著(p < 0.01), 且与物种和器官之间存在显著的交互作用。N处理提高了幼苗体内N含量, 导致不同器官N:P值有不同程度的增加。随N处理水平的升高, 多花山矾幼苗P含量下降, 黄心树幼苗P含量整体升高, 幼苗间P含量差异减小。在一定范围内, 植物幼苗N含量与土壤无机N含量之间存在极显著的相关性(p < 0.01)。不同器官之间相比, 植物幼苗根和茎的N内稳性比叶片更高, 即植物叶片对N沉降的响应更为敏感。     

Complex patterns of environmental niche evolution in Iberian columbines (genus Aquilegia,Ranunculaceae)

Aims This study explores the patterns of niche differentiation in a group of seven closely related columbines (genus Aquilegia, Ranunculaceae) from the Iberian Peninsula. Populations of these columbines are subject to complex patterns of divergent selection across environments, which partly explain the taxonomic structure of the group. This suggests the hypothesis that niche divergence must have occurred along the process of diversification of the group.Methods We used MaxEnt to build environmental niche models of seven subspecies belonging to the three species of Aquilegia present in the Iberian Peninsula. From these models, we compared the environmental niches through two different approaches: ENMtools and multivariate methods.Important findings MaxEnt distributions conformed closely to the actual distribution of the study taxa. ENMtools methods failed to uncover any clear patterns of niche differentiation or conservatism in Iberian columbines. Multivariate analyses indicate the existence of differentiation along altitudinal gradients and along a gradient of climatic conditions determined by the summer precipitation and temperatures. However, climatic conditions related to winter temperature and precipitation, as well as soil properties, were equally likely to show conservatism or divergence. The complex patterns of niche evolution we found suggest that Iberian Columbines have not been significantly constrained by forces of niche conservatism, so they could respond adaptively to the fast and profound climate changes in the Iberian Peninsula through the glacial cycles of the Pleistocene.     

Ecological risk and contamination history of heavy metals in the Andong tidal flat,Hangzhou Bay,China

In this study, we collected two sediment cores (C1 and C2) from the Andong tidal flat, Hangzhou Bay, and studied the temporal variations of heavy metals in the cores. Vertical distributions of heavy metals were almost unchanged in both the cores before 2000. After 2000, however, the heavy metal concentrations increased dramatically, suggesting that the sediments have been affected by enhanced human pollution in the recent decade. In the core C1, the sediments were severely polluted by Pb, moderately to considerably polluted by Cr and Zn, and low to moderately polluted by other heavy metals. The core C2 was relatively unpolluted before 2000 and low to moderately polluted after 2000. Multi-statistical analyses indicated that the core C1 was additionally contaminated by local human activities such as wastewater discharge and the Hangzhou Bay Bridge. The heavy metals in the core C2, however, were largely contributed by the Yangtze River and controlled by sedimentation process. The calculated sedimentary flux (4–8 g m^?2 a^?1) of heavy metals generally increased with time. It was closely related to the wastewater discharge in adjacent areas. This study reconstructed the local heavy metal pollution history and provides important information for environmental protection and policy making.     

Ecological risk assessment in a tropical wetland contaminated with gasoline: Tier 1

To assess natural attenuation and the efficiency of remediation actions after more than two years a large accident with gasoline spill contaminated a wetland in a tropical region, an Ecological Risk Assessment based on the Dutch Triad was applied. In total, eight surface water-sampling points were distributed randomly in the affected area and on reference area upstream the contaminated site, with similar ecological characteristics. Risks based on chemical, ecotoxicological, and ecological lines of evidence (LoE) were calculated to integrate the environmental risk indexes. The chemical risk was derived from toxic pressure coefficients based on the total BTEX and naphthalene concentrations. Ecotoxicological LoE based on acute toxicity with Daphnia similis and Aliivibrio fischeri bioassays and chronic toxicity with Desmodesmus subspicatus bioassay contributed to raise uncertainty due to low sensitivity of acute assays. Genotoxicity and endocrine disruption biomarkers of Oreochromis niloticus were used to calculate the Biomarker Stress Index (BSI) assumed as Ecological Risk Index. The integration of the Chemical Risk Index with BSI to estimate the Biological Vulnerability Index allowed a meaningful analysis of the threats to the aquatic ecosystem, thereby supporting managers and decision-makers.     

Persistent organic pollutants in Pakistan: Potential threat to ecological integrities in terms of genotoxicity and oxidative stress

As a consequence of both increasing population and industrialization in agro-economic sector, Pakistan has inevitably been confronted by multicomplex environmental challenges. Owing in part to poor regulatory framework, pollution due to persistent organic pollutants (POPs) has caused serious problems throughout the country. Resultantly, extensive use of POPs is causing vigorous deterioration of environment and human health. The current study addresses: (1) the general information on associated ecological effects and toxicity assessment by meta-analysis for local fauna and flora (2) their respective occurrence in living organisms; and (3) sources and distribution patterns of various POPs classes in environmental compartments of Pakistan. Based on the study, it can be concluded that the environment of Pakistan is highly contaminated with organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), and polychlorinated naphthalenes (PCNs), which is further supported with the meta-analysis. Nevertheless, unavailability of environmental quality standards and food safety for POPs render it a forthcoming challenge of multicompartment toxicity exposure. Therefore, strategies must be planned for risk assessment of biologically active POPs, while the POP waste inventory should be elevated, along with the necessary measures to promote appropriate handling and treatment of POP as a matter of prime importance.