基于灰关联分析的天津市气溶胶消光特征研究

根据天津市秋季(2006年10月10日～20日)消光系数(bext)、PM2.5、SO2、NOX、NO2、O3质量浓度及相对湿度监测结果,利用灰色关联分析法分析大气消光系数同空气中的几种主要污染要素的相关性。结果表明,与消光系数有关的几种主要指标的灰关联度序为PM2.5NOXRHNO2O3,其中PM2.5与消光系数的灰关联系数达到0.905,远高于其他相关指标。同时对PM2.5和消光系数相关分析表明,监测期间天津市PM2.5质量消光系数为6.04m2/g。     

A critical appraisal of population viability analysis

Population viability analysis (PVA) is useful in management of imperiled species. Applications range from research design, threat assessment, and development of management frameworks. Given the importance of PVAs, it is essential that they be rigorous and adhere to widely accepted guidelines; however, the quality of published PVAs is rarely assessed. We evaluated the quality of 160 PVAs of 144 species of birds and mammals published in peer-reviewed journals from 1990 to 2017. We hypothesized that PVA quality would be lower with generic programs than with custom-built programs; be higher for those developed for imperiled species; change over time; and be higher for those published in journals with high impact factors (IFs). Each included study was evaluated based on answers to an evaluation framework containing 32 questions reflecting whether and to what extent the PVA study adhered to published PVA guidelines or contained important PVA components. All measures of PVA quality were generally lower for studies based on generic programs. Conservation status of the species did not affect any measure of PVA quality, but PVAs published in high IF journals were of higher quality. Quality generally declined over time, suggesting the quantitative literacy of PVA practitioners has not increased over time or that PVAs developed by unskilled users are being published in peer-reviewed journals. Only 18.1% of studies were of high quality (score >75%), which is troubling because poor-quality PVAs could misinform conservation decisions. We call for increased scrutiny of PVAs by journal editors and reviewers. Our evaluation framework can be used for this purpose. Because poor-quality PVAs continue to be published, we recommend caution while using PVA results in conservation decision making without thoroughly assessing the PVA quality.     

Conservation resource allocation,small population resiliency,and the fallacy of conservation triage

Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.     

Metapopulation Extinction Risk under Spatially Autocorrelated Disturbance

Abstract:  Recent extinction models generally show that spatial aggregation of habitat reduces overall extinction risk because sites emptied by local extinction are more rapidly recolonized. We extended such an investigation to include spatial structure in the disturbance regime. A spatially explicit metapopulation model was developed with a wide range of dispersal distances. The degree of aggregation of both habitat and disturbance pattern could be varied from a random distribution, through the intermediate case of a fractal distribution, all the way to complete aggregation (single block). Increasing spatial aggregation of disturbance generally increased extinction risk. The relative risk faced by populations in different landscapes varied greatly, depending on the disturbance regime. With random disturbance, the spatial aggregation of habitat reduced extinction risk, as in earlier studies. Where disturbance was spatially autocorrelated, however, this advantage was eliminated or reversed because populations in aggregated habitats are at risk of mass extinction from coarse-scale disturbance events. The effects of spatial patterns on extinction risk tended to be reduced by long-distance dispersal. Given the high levels of spatial correlation in natural and anthropogenic disturbance processes, population vulnerability may be greatly underestimated both by classical (nonspatial) models and by those that consider spatial structure in habitat alone.     

Relationship between Population Size and Fitness

Abstract:  Long-term effective population size, which determines rates of inbreeding, is correlated with population fitness. Fitness, in turn, influences population persistence. I synthesized data from the literature concerning the effects of population size on population fitness in natural populations of plants to determine how large populations must be to maintain levels of fitness that will provide adequate protection against environmental perturbations that can cause extinction. Integral to this comment on what has been done and what needs to be done, sThe evidence suggests that there is a linear relationship between log population size and population fitness over the range of population sizes examined. More importantly, populations will have to be maintained at sizes of >2000 individuals to maintain population fitness at levels compatible with the conservation goal of long-term persistence. This approach to estimating minimum viable population size provides estimates that are in general agreement with those from numerous other studies and strengthens the argument that conservation efforts should ultimately aim at maintaining populations of several thousand individuals to ensure long-term persistence.     

The Role of Hybrid Vigor in the Replacement of Pecos Pupfish by Its Hybrids with Sheepshead Minnow

Abstract:  Many species are jeopardized by hybridization and genetic introgression with closely related species. Unfortunately, the mechanisms that promote or retard gene flow between divergent populations are little studied and poorly understood. Like many imperiled fish species, the Pecos pupfish ( Cyprinodon pecosensis ) is threatened with replacement by its hybrids with a close congener. We examined swimming performance and growth rate of hybrid pupfish to determine the role of hybrid vigor in the genetic homogenization of C. pecosensis by its hybrids with sheepshead minnow ( C. variegatus ). The F1 hybrids, backcross hybrids, and purebred C. variegatus displayed greater swimming endurance than purebred C. pecosensis . In addition, F1 hybrids and C. variegatus grew more rapidly than C. pecosensis . The ecological superiority of hybrids probably promoted their rapid spread through and beyond the historic range of C. pecosensis . These results indicate that eradication of hybrids and restoration of C. pecosensis to its native range is unlikely. Extinction of unique species via genetic homogenization can result from human activities that increase gene flow between historically fragmented populations; conservation managers must weigh the potential for such a catastrophe against the presumed benefits of increased interpopulation gene flow. This example illustrates how, after hybridization has occurred, conflict may arise between formerly complementary conservation goals.     

Company engagement with supply chains to protect biodiversity and rare,threatened, and endangered species

Future global megatrends project a population increase of 2 billion people between 2019 and 2050 and at least 1–2 billion people added to the global middle class between 2016 and 2030. In addition, 68% of the world's population is projected to be living in urban areas by 2050. With these projected large population increases and shifts, demand for food, water, and energy is projected to grow by approximately 35, 40, and 50%, respectively, between 2010 and 2030. In addition, between 1970 and 2014 there was an estimated 60% reduction in the number of wildlife in the world and an estimated net loss of 2.9 billion birds, or 29%, in North America between 1970 and 2018. Loss of species populations and number of species is interconnected with reduced health of biodiversity and ecosystems. Human activity has been the main catalyst for these substantial declines primarily through impacts on habitats. These losses are accelerating. Since a company's supply chain environmental impacts are often as great or greater than its own direct environmental impacts, it may be prudent for companies to engage with their supply chains to protect and enhance habitats and biodiversity and protect rare, threatened, and endangered species. As one example, companies may have opportunities and strategic reasons to include requirements in their supplier codes of conduct and supplier standards for suppliers to protect biodiversity and rare, threatened, and endangered species, as well as additional requirements to expand or enhance habitats and ecosystems to increase biodiversity. This article follows one pathway that companies could pursue further and with greater speed—to engage with their supply chains to strengthen supplier codes of conduct to protect biodiversity and rare, threatened, and endangered species. The importance of forests, private land, and landscape partnerships is discussed as means to protect much more of the planet's biodiversity and rare, threatened, and endangered species. Lastly, the article identifies examples of opportunities for companies to more formally incorporate biodiversity into their business, supply chain, and sustainability strategies.     

大气消光系数垂直分布模型及其适用性研究

大气消光系数垂直分布模型是利用卫星反演近地面颗粒物质量浓度的关键技术环节,同时也是分析边界层湍流场结构的重要途径,但其适用性问题至今尚不清晰.基于Logistic曲线模拟大气消光系数廓线的初步研究成果,结合太阳光度计（CE-318）观测的大气光学厚度（AOD）资料以及近地面能见度数据,提出了大气消光系数垂直分布Logistic模型的参数计算方法.针对成都市2013年6月~2014年5月期间的实例应用结果表明,在不稳定和中性层结条件下,Logistic模型和目前通用的负指数模型对大气消光系数垂直分布的模拟效果总体相当;但在持续稳定层结条件下,Logistic模型的模拟效果则显著占优.进一步分析指出,大气消光系数垂直分布Logistic模型更优的适用性主要在于其对近地层大气消光的复杂垂直形态具有良好的表征能力.