Potential Negative Ecological Effects of Corridors

Despite many studies showing that landscape corridors increase dispersal and species richness for disparate taxa, concerns persist that corridors can have unintended negative effects. In particular, some of the same mechanisms that underlie positive effects of corridors on species of conservation interest may also increase the spread and impact of antagonistic species (e.g., predators and pathogens), foster negative effects of edges, increase invasion by exotic species, increase the spread of unwanted disturbances such as fire, or increase population synchrony and thus reduce persistence. We conducted a literature review and meta‐analysis to evaluate the prevalence of each of these negative effects. We found no evidence that corridors increase unwanted disturbance or non‐native species invasion; however, these have not been well‐studied concerns (1 and 6 studies, respectively). Other effects of corridors were more often studied and yielded inconsistent results; mean effect sizes were indistinguishable from zero. The effect of edges on abundances of target species was as likely to be positive as negative. Corridors were as likely to have no effect on antagonists or population synchrony as they were to increase those negative effects. We found 3 deficiencies in the literature. First, despite studies on how corridors affect predators, there are few studies of related consequences for prey population size and persistence. Second, properly designed studies of negative corridor effects are needed in natural corridors at scales larger than those achievable in experimental systems. Third, studies are needed to test more targeted hypotheses about when corridor‐mediated effects on invasive species or disturbance may be negative for species of management concern. Overall, we found no overarching support for concerns that construction and maintenance of habitat corridors may result in unintended negative consequences. Negative edge effects may be mitigated by widening corridors or softening edges between corridors and the matrix. Other negative effects are relatively small and manageable compared with the large positive effects of facilitating dispersal and increasing diversity of native species. Efectos Negativos Potenciales de los Corredores     

铜对草鱼及花鲢的毒性预测：基于生物配体模型

试验配置不同胡敏酸浓度(DOC浓度为0.05、0.5、1、2、4 mg·L-1)下,分别对草鱼及花鲢进行铜的一系列96 h生物急性毒性试验,结果表明DOC浓度与LC50呈正相关关系,此与生物配体模型描述一致.利用两鱼种(Fathead minnow、Rainbow trout)的生物配体模型预测草鱼及花鲢的LC50,得出平均绝对偏差分别为591.2、157.14μg·L-1及728.18、91.24μg·L-1.在生物配体模型(biotic ligand model,BLM)铜形态分布平台下,得到草鱼及花鲢的LA50(以湿重计)依次为10.960nmol·g-1和3.978 nmol·g-1.通过校正草鱼及花鲢的LA50,得出平均绝对偏差依次为280.52μg·L-1和92.25μg·L-1,预测性能显著提高.基于所确立的LA50,通过搜集草鱼及花鲢的毒性数据,预测其LC50,得到平均绝对偏差分别为252.37μg·L-1和50.26μg·L-1,此证实基于生物配体模型的毒性预测具有一定的实用性.     

Measurement and Management of Human-Induced Patterns of Forest Fragmentation: A Case Study

In many tropical developing countries, the twin pressures of population and poverty are resulting in substantial fragmentation of forests, increasing the probability of extinction for many species, Forest fragmentation occurs when large contiguous forests are perforated by small holes or broken up into edges and smaller patches to form a nonforested matrix of open spaces. Thus, forest fragmentation refers not only to the area of forest cleared, but also to the pattern of this clearance, the resulting forest’s spatial properties. Both characteristics are important for species survivability. Apart from opening up forests to many abiotic and biotic influences, fragmentation can affect species dispersal and migration through its effects on forest connectivity. Landscape ecology conceptualizes connectivity as a gradient of critical thresholds, ranging from the large intact forest to the small unconnected forest patch. This article reports results from a multiple-scale analysis of forest fragmentation in Jamaica’s Cockpit Country, an area of once contiguous forest now under threat from human encroachment. Spatial forest data derived from classification of ETM+ satellite imagery are used to measure fragmentation patterns representing various degrees of forest connectivity and density. The results suggest that, overall, 81% of the region is in forest. However, fragmentation patterns also suggest that this forest is riven with extensive perforations indicative of an early stage in the decline of contiguity. The results provided by the spatial fragmentation model are a first step in the design of effective conservation and rehabilitation plans for the area. The article concludes with a discussion of possible multiscale management options for the region.     

松花江流域大型底栖动物生物完整性指数构建及其适用性

利用生物完整性指数评价河流健康状态,对于水环境管理决策具有重要的实践意义。基于大型底栖动物构建生物完整性指数(B-IBI),并评价松花江流域的水生态系统健康状况。在松花江主要干支流设定37个采样点,分别于2016年6、9月进行环境因子和大型底栖动物调查研究。最终从28个候选参数中确定了种类总数、摇蚊种类数、敏感种百分比、Hilsenhoff指数、Marglef指数作为核心参数构建B-IBI。通过0～10赋分法,计算得到了松花江流域全部采样点的生物完整性评价得分。结果显示,松花江流域内60%区域生物状态存在不同程度的损害。另外,B-IBI能够综合反映松花江大型底栖动物群落多样性、生境质量、理化水质等,具有一定的适用性。     

Don’t Fight the Site: Three Geomorphic Considerations in Catchment-Scale River Rehabilitation Planning

Three geomorphic considerations that underpin the design and implementation of realistic and strategic river conservation and rehabilitation programs that work with the nature are outlined. First, the importance of appreciating the inherent diversity of river forms and processes is discussed. Second, river dynamics are appraised, framing the contemporary behavioral regime of a reach in relation to system evolution to explain changes to river character and behavior over time. Third, the trajectory of a reach is framed in relation to downstream patterns of river types, analyzing landscape connectivity at the catchment scale to interpret geomorphic river recovery potential. The application of these principles is demonstrated using extensive catchment-scale analyses of geomorphic river responses to human disturbance in the Bega and Upper Hunter catchments in southeastern Australia. Differing implications for reach- and catchment-scale rehabilitation planning prompt the imperative that management practices work with nature rather than strive to ‘fight the site.’     

Octanol–air partition coefficients of polybrominated biphenyls

The octanol–air partition coefficients (K_OA) for PBB15, PBB26, PBB31, PBB49, PBB103 and PBB153 were determined as a function of temperature using a gas chromatographic retention time technique with 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (p,p′-DDT) as a reference substance. The internal energies of phase change from octanol to air (Δ_OAU) were calculated for the six compounds and were in the range from 74 to 116 kJ mol⁻¹. Simple regression equations of log K_OA versus relative retention times (RRTs) on gas chromatography (GC), and log K_OA versus molecular connectivity indexes (MCI) were obtained, for which the correlation coefficients (r²) were greater than 0.985 at 283.15 K and 298.15 K. Thus the K_OA values of the remaining PBBs can be predicted by using their RRTs and MCI according to these relationships.     

一个新的拓扑指数用于芳烃化合物溶解度、分配系数及生物毒性的研究

在分子拓扑理论的基础上,提出了一个新的拓扑指数Yx,并用Yx研究了芳烃化合物的溶解度、分配系数及生物毒(活）性,给出了相关方程。结果表明,新方法计算方便,物理意义明确,预测值与相应的实验值较吻合。     

城镇化下平原水系变化及河网连通性影响研究

针对平原区城镇化背景下水系减少及连通受阻等下垫面变化引起的洪涝加剧问题,综合考虑水系结构和水力特性等因素,建立满足行洪排涝需求的平原水系连通度量方法,并以浙东沿海平原河网区为例,分析了城镇化下平原水系特征变化及其对河网连通度的影响。结果表明:1近20a来研究区水系数量和结构复杂性均存在不同程度的衰减,河网密度和水面率分别减少20%和30%左右,水系尤其是低等级河道的减少导致河网结构趋于骨干化;2河网连通度受水面率等数量特征和水系空间连接结构的共同影响,在水系数量持续减少情况下,整个河网连通度呈现先减少后增加的趋势,说明了骨干河道工程对水系空间结构特征的优化,可缓解水系减弱对河网连通的负面效应;3建立的河网连通度方法合理反映了水系数量和结构变化下的河网连通度演变规律,以及水系变化下区域排涝能力的空间差异特征,具有操作性强特点。     

应用底栖动物为指示生物的松花江干流水生态预警研究

指示生物监测及水生态预警是利用水环境中指示物种的数量、群落结构指标和个体生理指标等描述水生态系统的健康状态,其相比于常规理化监测和预警更直接地反映水体的生态质量。本研究在松花江干流2012—2015年大型底栖无脊椎动物监测结果的基础上,结合各监测点生态质量管理目标,通过分析物种的种类、出现的频次、物种污染敏感性(耐污值),尝试提出了松花江干流监控断面以底栖动物为指示生物的水生态预警模式,研究思路和结果对流域水环境风险管理指标的拓展有积极作用。     

基于MSPA与MCR模型的余江县生态网络构建基于MSPA与MCR模型的余江县生态网络构建

在我国社会经济快速发展的背景下,城市化进程的不断推进导致城市生态斑块日益减少,生态环境问题正在逐年增加,构建生态网络是改善城市生态环境与服务功能的有效方法之一。以余江县为研究区,采用形态学空间格局分析(MSPA)方法和景观指数法,提取对生态网络具有重要意义的生态源地,并基于MCR模型构建综合阻力面,采用最小成本路径方法生成潜在廊道,再基于重力模型、中介中心度等对关键廊道及踏脚石斑块进行识别并提取,从而构建研究区潜在生态网络。结果表明：MSPA方法能够与MCR模型有机的结合,通过定量的分析识别出研究区潜在生态廊道,并根据斑块的中介作用选定踏脚石斑块,明确研究区景观要素的保护优先度,将景观中的潜在生态源地及廊道作为生态网络构建的主要依据,能够更加科学地为余江县生态网络的构建提供指导,同时也可为其他区域提供参考。