Occurrence of the non-native annual bluegrass on the Antarctic mainland and its negative effects on native plants

Few non-native species have colonized Antarctica, although increased human activity and accelerated climate change may increase their number, distributional range, and effects on native species on the continent. We searched 13 sites on the maritime Antarctic islands and 12 sites on the Antarctic Peninsula for annual bluegrass (Poa annua), a non-native flowering plant. We also evaluated the possible effects of competition between P. annua and 2 vascular plants native to Antarctica, Antarctic pearlwort (Colobanthus quitensis) and Antarctic hairgrass (Deschampsia antarctica). We grew the native species in experimental plots with and without annual bluegrass under conditions that mimicked the Antarctic environment. After 5 months, we measured photosynthetic performance on the basis of chlorophyll fluorescence and determined total biomass of both native species. We found individual specimens of annual bluegrass at 3 different sites on the Antarctic Peninsula during the 2007-2008 and 2009-2010 austral summers. The presence of bluegrass was associated with a statistically significant reduction in biomass of pearlwort and hairgrass, whereas the decrease in biomass of bluegrass was not statistically significant. Similarly, the presence of bluegrass significantly reduced the photosynthetic performance of the 2 native species. Sites where bluegrass occurred were close to major maritime routes of scientific expeditions and of tourist cruises to Antarctica. We believe that if current levels of human activity and regional warming persist, more non-native plant species are likely to colonize the Antarctic and may affect native species.     

Setting conservation priorities for migratory networks under uncertainty

Conserving migratory species requires protecting connected habitat along the pathways they travel. Despite recent improvements in tracking animal movements, migratory connectivity remains poorly resolved at a population level for the vast majority of species, thus conservation prioritization is hampered. To address this data limitation, we developed a novel approach to spatial prioritization based on a model of potential connectivity derived from empirical data on species abundance and distance traveled between sites during migration. We applied the approach to migratory shorebirds of the East Asian‐Australasian Flyway. Conservation strategies that prioritized sites based on connectivity and abundance metrics together maintained larger populations of birds than strategies that prioritized sites based only on abundance metrics. The conservation value of a site therefore depended on both its capacity to support migratory animals and its position within the migratory pathway; the loss of crucial sites led to partial or total population collapse. We suggest that conservation approaches that prioritize sites supporting large populations of migrants should, where possible, also include data on the spatial arrangement of sites.     

Consistency of effects of tropical‐forest disturbance on species composition and richness relative to use of indicator taxa

Lawton et al. (1998) found, in a highly cited study, that the species richness of 8 taxa each responds differently to anthropogenic disturbance in Cameroon forests. Recent developments in conservation science suggest that net number of species is an insensitive measure of change and that understanding which species are affected by disturbance is more important. It is also recognized that all disturbance types are not equal in their effect on species and that grouping species according to function rather than taxonomy is more informative of responses of biodiversity to change. In a reanalysis of most of the original Cameroon data set (canopy and ground ants, termites, canopy beetles, nematodes, and butterflies), we focused on changes in species and functional composition rather than richness and used a more inclusive measure of forest disturbance based on 4 component drivers of change: years since disturbance, tree cover, soil compaction, and degree of tree removal. Effects of disturbance on compositional change were largely concordant between taxa. Contrary to Lawton et al.’s findings, species richness for most groups did not decline with disturbance level, providing support for the view that trends in species richness at local scales do not reflect the resilience of ecosystems to disturbance. Disturbance affected species composition more strongly than species richness for butterflies, canopy beetles, and litter ants. For these groups, disturbance caused species replacements rather than just species loss. Only termites showed effects of disturbance on species richness but not composition, indicating species loss without replacement. Although disturbance generally caused changes in composition, the strength of this relationship depended on the disturbance driver. Butterflies, litter ants, and nematodes were correlated with amount of tree cover, canopy beetles were most strongly correlated with time since disturbance, and termites were most strongly correlated with degree of soil disturbance. There were moderately divergent responses to disturbance between functional feeding groups. Disturbance was most strongly correlated with compositional differences of herbivores within beetles and nematodes and humus feeders within termites. Our results suggest that consideration of the impact of different forms of disturbance on species and functional composition, rather than on net numbers of species, is important when assessing the impacts of disturbance on biodiversity.     

苯酚的超临界水氧化试验

以自建的一套连续式超临界水氧化装置的温度，压力，溶氧量和流量等参数的可控性进行了实验，并在此基础上进行了苯酚的超临界水氧化研究。结果表明：所建立的装置能比较精确控制各种条件参数，是可靠的超临界水氧化试验研究装置。在氧气过量的条件下，停留时间是影响苯酚在超临界水中氧化分解的主要因素，反应的温度和压力升高导致苯致苯酚去除率的增大，只要有足够的氧气，苯酚起始浓度的增加对苯酚的转化率影响不明显，在实验条件下，溶液中苯酚的去除动力学对苯酚是一级，氧气是零级。     

Monitoring of Biological Diversity: a Common-Ground Approach

Abstract:  Practical approaches to monitoring biological diversity vary widely among countries, and the accumulating data are frequently not generalizable at the international scale. Although many present monitoring schemes, especially in developed countries, produce highly complex data, there is often a lack of basic data about the level and spatial distribution of biodiversity. We augmented the general framework for improving biomonitoring, proposed by Green et al. (2005) , and identified its core tasks and attributes. The first priority for a more unified biodiversity monitoring is to agree on a minimum set of core tasks and attributes, which will make it possible to build a standardized biomonitoring system even in countries with few resources. Our scheme has two main organizational levels—taxa and ecosystems. The basic elements of the biomonitoring system proposed are recording of presence and absence of taxa and ecosystems in a target area, mapping of their distribution in space, and assessment of their status. All the elements have to be repeated over time. Although these tasks are fundamental, they are frequently not considered in currently functioning biomonitoring programs. The whole system has to be hierarchical and additive: if more resources are available, new activities may be added to the basic routine. Agreeing on a common standard will facilitate aggregating measures of biodiversity status and trends into regional and global indices. This information will relate directly to several Convention on Biological Diversity indicators for assessing progress toward the 2010 Biodiversity Target.     

Determining Optimal Population Monitoring for Rare Butterflies

Abstract: Determining population viability of rare insects depends on precise, unbiased estimates of population size and other demographic parameters. We used data on the endangered St. Francis' satyr butterfly (Neonympha mitchellii francisci) to evaluate 2 approaches (mark–recapture and transect counts) for population analysis of rare butterflies. Mark–recapture analysis provided by far the greatest amount of demographic information, including estimates (and standard errors) of population size, detection, survival, and recruitment probabilities. Mark–recapture analysis can also be used to estimate dispersal and temporal variation in rates, although we did not do this here. Models of seasonal flight phenologies derived from transect counts (Insect Count Analyzer) provided an index of population size and estimates of survival and statistical uncertainty. Pollard–Yates population indices derived from transect counts did not provide estimates of demographic parameters. This index may be highly biased if detection and survival probabilities vary spatially and temporally. In terms of statistical performance, mark–recapture and Pollard–Yates indices were least variable. Mark–recapture estimates were less likely to fail than Insect Count Analyzer, but mark–recapture estimates became less precise as sampling intensity decreased. In general, count‐based approaches are less costly and less likely to cause harm to rare insects than mark–recapture. The optimal monitoring approach must reconcile these trade‐offs. Thus, mark–recapture should be favored when demographic estimates are needed, when financial resources enable frequent sampling, and when marking does not harm the insect populations. The optimal sampling strategy may use 2 sampling methods together in 1 overall sampling plan: limited mark–recapture sampling to estimate survival and detection probabilities and frequent but less expensive transect counts.     

Using adsorption and sulphide precipitation as the principal removal mechanisms of arsenic from a constructed wetland – a critical review

This review has been undertaken to understand the role of various parameters such as redox potential, microbes, and organic matters on the fate and transport of arsenic in the constructed wetland. A conceptual diagram of arsenic fate and transport in the constructed wetland was developed. Role of various minerals which are produced due to microbial activities are described. The role of these minerals on arsenic adsorption is discussed. It was envisaged that iron sulphide would be the main adsorbent for arsenic in microbe-mediated adsorption process. Beside microbe-mediated arsenic adsorption, roles of various microbes, such as sulphate reducers and methane producers, on arsenic transformation are discussed. Role of various organic carbon sources and electron acceptors on the proliferation of the above mentioned microbes with respect to arsenic transformation was envisaged. Role of dissolved organic matters on arsenic transformation and transport was also discussed in details. To strengthen the review, laboratory studies and modelling of arsenic adsorption and transformation using the Visual Minteq were appended.     

地下水中铵态氮的迁移转化过程

铵态氮进入地下水的主要途径是土壤淋失,通过室内土柱淋滤实验研究铵态氮在土壤中的迁移转化过程,测定不同时间和不同深度土壤中铵态氮及其转化物硝态氮和亚硝态氮的浓度变化,分析了影响铵态氮迁移转化的因素。实验表明：在土壤饱和、持续淋滤条件下,土柱中随采样深度的增加,铵态氮穿透时间延长,依次滞后;通过硝化能力分析,土柱上层发生了轻微的硝化反应,土柱底部发生了反硝化反应,导致硝态氮的浓度衰减。研究认为在铵态氮的迁移转化过程中,当入渗铵态氮浓度较低时,影响铵态氮迁移转化的显著因素是土壤对铵态氮的吸附;当入渗铵态氮浓度较大时,影响铵态氮迁移转化的显著因素是生物作用导致的铵态氮的硝化,以及土壤的渗透系数、弥散度等因素。     

Scaling range sizes to threats for robust predictions of risks to biodiversity

Assessments of risk to biodiversity often rely on spatial distributions of species and ecosystems. Range‐size metrics used extensively in these assessments, such as area of occupancy (AOO), are sensitive to measurement scale, prompting proposals to measure them at finer scales or at different scales based on the shape of the distribution or ecological characteristics of the biota. Despite its dominant role in red‐list assessments for decades, appropriate spatial scales of AOO for predicting risks of species’ extinction or ecosystem collapse remain untested and contentious. There are no quantitative evaluations of the scale‐sensitivity of AOO as a predictor of risks, the relationship between optimal AOO scale and threat scale, or the effect of grid uncertainty. We used stochastic simulation models to explore risks to ecosystems and species with clustered, dispersed, and linear distribution patterns subject to regimes of threat events with different frequency and spatial extent. Area of occupancy was an accurate predictor of risk (0.81<|r|<0.98) and performed optimally when measured with grid cells 0.1–1.0 times the largest plausible area threatened by an event. Contrary to previous assertions, estimates of AOO at these relatively coarse scales were better predictors of risk than finer‐scale estimates of AOO (e.g., when measurement cells are <1% of the area of the largest threat). The optimal scale depended on the spatial scales of threats more than the shape or size of biotic distributions. Although we found appreciable potential for grid‐measurement errors, current IUCN guidelines for estimating AOO neutralize geometric uncertainty and incorporate effective scaling procedures for assessing risks posed by landscape‐scale threats to species and ecosystems.