Species distribution modelling—Effect of design and sample size of pseudo-absence observations

We explored the effect of varying pseudo-absence data in species distribution modelling using empirical data for four real species and simulated data for two imaginary species. In all analyses we used a fixed study area, a fixed set of environmental predictors and a fixed set of presence observations. Next, we added pseudo-absence data generated by different sampling designs and in different numbers to assess their relative importance for the output from the species distribution model. The sampling design strongly influenced the predictive performance of the models while the number of pseudo-absences had minimal effect on the predictive performance. We attribute much of these results to the relationship between the environmental range of the pseudo-absences (i.e. the extent of the environmental space being considered) and the environmental range of the presence observations (i.e. under which environmental conditions the species occurs). The number of generated pseudo-absences had a direct effect on the predicted probability, which translated to different distribution areas. Pseudo-absence observations that fell within grid cells with presence observations were purposely included in our analyses. We discourage the practice of excluding certain pseudo-absence data because it involves arbitrary assumptions about what are (un)suitable environments for the species being modelled.     

Mine-drainage treatment wetland as habitat for herptofaunal wildlife

Land reclamation techniques that incorporate habitat features for herptofaunal wildlife have received little attention. We assessed the suitability of a wetland, constructed for the treatment of mine-water drainage, for supporting herptofaunal wildlife from 1988 through 1990 using diurnal and nocturnal surveys. Natural wetlands within the surrounding watershed were also monitored for comparison. The treatment wetland supported the greatest abundance and species richness of herptofauna among the sites surveyed. Abundance was a function of the frog density, particularly green frogs (Rana clamitans) and pickerel frogs (R. palustris), while species richness was due to the number of snake species found. The rich mix of snake species present at the treatment wetland was believed due to a combination of an abundant frog prey base and an amply supply of den sites in rock debris left behind from earlier surface-mining activities. Nocturnal surveys of breeding male frogs demonstrated highest breeding activity at the treatment wetland, particularly for spring peepers (Hyla crucifer). Whole-body assays of green frog and bullfrog (R. catesbeiana) tissues showed no differences among sites in uptake of iron, aluminum, and zinc; managanese levels in samples from the treatment wetland were significantly lower than those from natural wetlands. These results suggest that wetlands established for water quality improvement can provide habitat for reptiles and amphibians, with the species composition dependent on the construction design, the proximity to source populations, and the degree of acidity and heavy-metal concentrations in drainage waters.     

Balancing urban development and endangered species: The coachella valley habitat conservation plan

Habitat conservation plans (HCPs) permitted under Section 10(A) of the federal Endangered Species Act, have been increasingly used to overcome conflicts between urban development and species conservation. This article profiles one such HCP, the Coachella Valley (CA) Fringe-Toed Lizard Habitat Conservation Plan. The second HCP officially approved by the US Fish and Wildlife Service, the Coachella Valley case is frequently cited as a model for resolving conservation and development conflicts. The article begins with a discussion of the use of HCPs, and then provides a detailed discussion of Coachella Valley experience, its history, specific provisions, and success to date. A final section examines whether Coachella Valley does in fact represent a positive model. It is argued that the HCP has been less than fully successful and leaves unresolved a series of fundamental ethical and policy questions concerning the protection of endangered species. Funding for this report was provided by the National Fish and Wildlife Foundation. Any opinions, findings, conclusions, or recommendations are those of the author and do not necessarily represent the views of the Foundation.     

Environmental Management and the New Politics of Western Water: The Animas-La Plata Project and Implementation of the Endangered Species Act

/ This paper explores the new politics of western water policy through an examination of the Animas-La Plata water project and implementation of the Endangered Species Act. It is suggested that the focus of western water programming has shifted from the source of distributed funds, the United States Congress, to the agencies originally created to deliver federal benefits because funding for new project construction has not been forthcoming. Under this new system, members of Congress continue to excite their constituents with promises of money for new project starts, while the administrative agencies perform the myriad duties needed to keep these projects alive. The result is that political objectives have replaced operational/management objectives in administrative processes. In this case, the author demonstrates how resource managers in the Bureau of Reclamation manipulated hydrological analysis to control administrative process, why their manipulation was unfair, and perhaps illegal, and why biologists from the US Fish and Wildlife Service accepted the analysis. While ostensibly protecting all interests, the result is that none of the objectives of federal water programming are achieved. KEY WORDS: Environmental management; Administrative politics; Water policy; Endangered Species Act; Animas-La Plata, Bureau of Reclamation     

Human impact on beach and foredune vegetation of North Padre Island,Texas

Vehicular and pedestrian traffic decreased top and root production, percent cover, and diversity of vegetation, and modified species composition on beach and foredune areas of Padre Island National Seashore and Nueces County Park. Degradation of vegetal cover was directly related to the type and intensity of traffic; species in heavily trafficked areas represented earlier successional stages than those in comparable undisturbed areas.     

Decision‐Making Triggers in Adaptive Management

We analyzed whether decision‐making triggers increase accountability of adaptive‐management plans. Triggers are prenegotiated commitments in an adaptive‐management plan that specify what actions are to be taken and when on the basis of information obtained from monitoring. Triggers improve certainty that particular actions will be taken by agencies in the future. We conducted an in‐depth, qualitative review of the political and legal contexts of adaptive management and its application by U.S. federal agencies. Agencies must satisfy the judiciary that adaptive‐management plans meet substantive legal standards and comply with the U.S. National Environmental Policy Act. We examined 3 cases in which triggers were used in adaptive‐management plans: salmon (Oncorhynchus spp.) in the Columbia River, oil and gas development by the Bureau of Land Management, and a habitat conservation plan under the U.S. Endangered Species Act. In all the cases, key aspects of adaptive management, including controls and preidentified feedback loops, were not incorporated in the plans. Monitoring and triggered mitigation actions were limited in their enforceability, which was contingent on several factors, including which laws applied in each case and the degree of specificity in how triggers were written into plans. Other controversial aspects of these plans revolved around who designed, conducted, interpreted, and funded monitoring programs. Additional contentious issues were the level of precaution associated with trigger mechanisms and the definition of ecological baselines used as points of comparison. Despite these challenges, triggers can be used to increase accountability, by predefining points at which an adaptive management plan will be revisited and reevaluated, and thus improve the application of adaptive management in its complicated political and legal context. Detonadores de la Toma de Decisiones en el Manejo Adaptativo     

贝纳德效应和地震预报

本文根据海城地震前后重力变化的实测资料提出重力加速度随时间变化的一种简化表示。在重力发生扰动时对贝纳德问题的动力学方程进行求解。计算结果表明,在强地震的孕育期,贝纳德花样的周期变化在一定时间后将自动停止。这个结论的验证可以作为一种新的地震预测方法的理论基础。     

Intraspecific Chromosome Number Variation: a Neglected Threat to the Conservation of Rare Plants

Abstract: The effectiveness of rare plant conservation will increase when life history, demographic, and genetic data are considered simultaneously. Inbreeding depression is a widely recognized genetic concern in rare plant conservation, and the mixing of genetically diverse populations in restoration efforts is a common remedy. Nevertheless, if populations with unrecognized intraspecific chromosome variation are crossed, progeny fitness losses will range from partial to complete sterility, and reintroductions and population augmentation of rare plants may fail. To assess the current state of cytological knowledge of threatened and endangered plants in the continental United States, we searched available resources for chromosome counts. We also reviewed recovery plans to discern whether recovery criteria potentially place listed species at risk by requiring reintroductions or population augmentation in the absence of cytological information. Over half the plants lacked a chromosome count, and when a taxon did have a count it generally originated from a sampling intensity too limited to detect intraspecific chromosome variation. Despite limited past cytological sampling, we found 11 plants with documented intraspecific cytological variation, while 8 others were ambiguous for intraspecific chromosome variation. Nevertheless, only one recovery plan addressed the chromosome differences. Inadequate within‐species cytological characterization, incomplete sampling among listed taxa, and the prevalence of interspecific and intraspecific chromosome variation in listed genera, suggests that other rare plants are likely to have intraspecific chromosome variation. Nearly 90% of all recovery plans called for reintroductions or population augmentation as part of recovery criteria despite the dearth of cytological knowledge. We recommend screening rare plants for intraspecific chromosome variation before reintroductions or population augmentation projects are undertaken to safeguard against inadvertent mixtures of incompatible cytotypes.     

Quantitative analysis of riparian herbaceous community in Liaohe River Conservation Area and its tributaries北大核心CSCD

Research on community characteristics of riparian herbs is an important scientific basis of riparian vegetation rehabilitation. This study aimed to investigate the species diversity and quantitative characteristics of riparian herbs in Liaohe River Conservation Area and its tributaries. Herbaceous communities were investigated by sample line method. Group average clustering analysis and detrended correspondence analysis (DCA) were used to find the major environmental factors affecting the distribution pattern of riparian herbaceous communities. The result showed altogether 154 herbaceous species, belonging to 40 families and 96 genera. The riparian herbaceous species diversity was found to be correlated to river slope, sinuosity and stream order, being lower in rivers of mountain area than in rivers of plain area, and higher in tributaries than in Liaohe River Conservation Area. Clustering analysis classified the herbaceous communities into 23 types, being dominated by hygrophytes including communities of Echinochloa crusgalli, Oenanthe javanica, Polygonum hydropiper, Murdannia keisak, Artemisia selengensis, Scirpus triqueter, Heleocharis soloniensis, Pycreus sanguinolentus, Cyperus fuscus, Phragmites australis, Polygonum amphibium, Carex diandra + Artemisia selengensis and Carex diandra + Rorippa islandica. Correlation analysis between DCA ordination axes and environmental factors showed that the altitude, river slope, sinuosity and stream level were the major environmental factors affecting the distribution pattern of herbaceous communities in the riparian zone of Liaohe River Conservation Area and its tributaries. The results of CCA showed that the contribution ratio of stream level was the highest, followed by altitude and slope, with sinuosity the last. The results suggested that riparian herbaceous characteristics are affected by the comprehensive force of altitude, river slope, sinuosity and stream order, and that Calamagrostis epigeios, Triarrhena sacchariflora and Phragmites australis are suitable species for riparian vegetation rehabilitation.     

Predicted no-effect concentrations for mercury species and ecological risk assessment for mercury pollution in aquatic environment

Mercury(Hg) exists in different chemical forms presenting varied toxic potentials. It is necessary to explore an ecological risk assessment method for different mercury species in aquatic environment. The predicted no-effect concentrations(PNECs) for Hg(Ⅱ) and methyl mercury(Me Hg) in the aqueous phase, calculated using the species sensitivity distribution method and the assessment factor method, were 0.39 and 6.5 × 10-3μg/L, respectively. The partition theory of Hg between sediment and aqueous phases was considered, along with PNECs for the aqueous phase to conduct an ecological risk assessment for Hg in the sediment phase. Two case studies, one in China and one in the Western Black Sea, were conducted using these PNECs. The toxicity of mercury is heavily dependent on their forms,and their potential ecological risk should be respectively evaluated on the basis of mercury species.