Relationships between Human Disturbance and Wildlife Land Use in Urban Habitat Fragments

Abstract: Habitat remnants in urbanized areas typically conserve biodiversity and serve the recreation and urban open‐space needs of human populations. Nevertheless, these goals can be in conflict if human activity negatively affects wildlife. Hence, when considering habitat remnants as conservation refuges it is crucial to understand how human activities and land uses affect wildlife use of those and adjacent areas. We used tracking data (animal tracks and den or bed sites) on 10 animal species and information on human activity and environmental factors associated with anthropogenic disturbance in 12 habitat fragments across San Diego County, California, to examine the relationships among habitat fragment characteristics, human activity, and wildlife presence. There were no significant correlations of species presence and abundance with percent plant cover for all species or with different land‐use intensities for all species, except the opossum (Didelphis virginiana), which preferred areas with intensive development. Woodrats (Neotoma spp.) and cougars (Puma concolor) were associated significantly and positively and significantly and negatively, respectively, with the presence and prominence of utilities. Woodrats were also negatively associated with the presence of horses. Raccoons (Procyon lotor) and coyotes (Canis latrans) were associated significantly and negatively and significantly and positively, respectively, with plant bulk and permanence. Cougars and gray foxes (Urocyon cinereoargenteus) were negatively associated with the presence of roads. Roadrunners (Geococcyx californianus) were positively associated with litter. The only species that had no significant correlations with any of the environmental variables were black‐tailed jackrabbits (Lepus californicus) and mule deer (Odocoileus hemionus). Bobcat tracks were observed more often than gray foxes in the study area and bobcats correlated significantly only with water availability, contrasting with results from other studies. Our results appear to indicate that maintenance of habitat fragments in urban areas is of conservation benefit to some animal species, despite human activity and disturbance, as long as the fragments are large.     

内蒙古某饮水型砷中毒病区人群体内砷蓄积与砷代谢的年内变化特征

为分析砷暴露人群砷含量标志物的季节差异特征,本文测定内蒙古某饮水型地方性砷中毒村78名居民发砷、指甲砷、以及尿液总砷和各形态砷的含量,并分析其年内变化特征及相关性.结果表明,平水期、丰水期和枯水期的发砷含量均值分别为2.08、1.43、3.60 μg·g-1,尿液总砷含量均值分别为236.63、184.29、306.72 μg·L-1,指甲砷含量均值则分别为3.21、2.84、3.40 μg·g-1.经单因素方差分析（ANOVA）,发砷、尿液各形态砷含量存在显著的季节差异,表现为枯水期 > 平水期 > 丰水期;指甲砷含量的季节差异不显著,这可能是不同生物标志物对水砷含量变化响应速度的差异导致的.发砷、尿液无机砷和一甲基砷（MMA）含量有显著的性别差异,男性高于女性;指甲砷、尿液总砷和二甲基砷（DMA）含量性别差异不显著.发砷、尿液总砷和DMA含量均显著正相关,且与水砷含量的季节变化趋势一致,说明指甲砷比发砷与尿砷更能反映较长期的砷暴露特征.     

基于多维化学指纹分析的人体内颗粒态污染物的溯源方法

细颗粒物污染是当前重要环境污染问题,也是影响我国国民健康的重要风险因素之一。流行病学研究表明,长期的环境细颗粒物暴露会增加呼吸系统,心血管系统,神经退行性疾病等的患病风险。正确认识人体内颗粒态污染物的真实赋存及来源是科学评估其健康风险的关键,是以公共健康为导向的颗粒物污染防控的迫切需求。然而,人体内生物基质极其复杂,且自身的生物矿化作用可生成生物源性的颗粒物,这为人体内高动态的颗粒态物质的溯源带来了严峻的方法学挑战。本文综述了当前人体内颗粒态物质溯源方法研究的最新进展,提出基于多重化学指纹分析的系统溯源方法,为未来更精准快捷的体内颗粒态污染物的溯源研究提供技术支持。     

土壤-作物系统重金属污染及防治研究进展

我国土壤污染中无机污染占比较大,而无机污染中重金属污染问题尤为突出。当前,由于工农业生产、矿产开采、燃料燃烧和车辆排放等各种人类活动,土壤-作物系统中的重金属污染状况正在恶化,且农产品受重金属影响日趋严重。本文概括了土壤-作物系统中重金属的来源、危害,阐述了该系统重金属的污染现状及人体健康风险评价,着重分析了重金属生物有效性对人体健康风险的影响,总结了当前用于治理土壤重金属污染的修复技术和防控措施,以期为土壤污染修复及防治工作提供参考,降低土壤重金属污染产生的人体健康风险,保障食物安全。     

Salvage Logging, Ecosystem Processes, and Biodiversity Conservation

Abstract:  We summarize the documented and potential impacts of salvage logging—a form of logging that removes trees and other biological material from sites after natural disturbance. Such operations may reduce or eliminate biological legacies, modify rare postdisturbance habitats, influence populations, alter community composition, impair natural vegetation recovery, facilitate the colonization of invasive species, alter soil properties and nutrient levels, increase erosion, modify hydrological regimes and aquatic ecosystems, and alter patterns of landscape heterogeneity. These impacts can be assigned to three broad and interrelated effects: (1) altered stand structural complexity; (2) altered ecosystem processes and functions; and (3) altered populations of species and community composition. Some impacts may be different from or additional to the effects of traditional logging that is not preceded by a large natural disturbance because the conditions before, during, and after salvage logging may differ from those that characterize traditional timber harvesting. The potential impacts of salvage logging often have been overlooked, partly because the processes of ecosystem recovery after natural disturbance are still poorly understood and partly because potential cumulative effects of natural and human disturbance have not been well documented. Ecologically informed policies regarding salvage logging are needed prior to major natural disturbances so that when they occur ad hoc and crisis-mode decision making can be avoided. These policies should lead to salvage-exemption zones and limits on the amounts of disturbance-derived biological legacies (e.g., burned trees, logs) that are removed where salvage logging takes place. Finally, we believe new terminology is needed. The word salvage implies that something is being saved or recovered, whereas from an ecological perspective this is rarely the case.     

Limitations of Gravity Models in Predicting the Spread of Eurasian Watermilfoil

Abstract: The effects of non‐native invasive species are costly and environmentally damaging, and resources to slow their spread and reduce their effects are scarce. Models that accurately predict where new invasions will occur could guide the efficient allocation of resources to slow colonization. We assessed the accuracy of a model that predicts the probability of colonization of lakes in Wisconsin by Eurasian watermilfoil (Myriophyllum spicatum). We based this predictive model on 9 years (1990–1999) of sequence data of milfoil colonization of lakes larger than 25 ha (n =1803). We used milfoil colonization sequence data from 2000 to 2006 to test whether the model accurately predicted the number of lakes that actually were colonized from among the 200 lakes identified as being most likely to be colonized. We found that a lake's predicted probability of colonization was not correlated with whether a lake actually was colonized. Given the low predictability of colonization of specific lakes, we compared the efficacy of preventing milfoil from leaving occupied sites, which does not require predicting colonization probability, with protecting vacant sites from being colonized, which does require predicting colonization probability. Preventing organisms from leaving colonized sites reduced the likelihood of spread more than protecting vacant sites. Although we focused on the spread of a single species in a particular region, our results show the shortcomings of gravity models in predicting the spread of numerous non‐native species to a variety of locations via a wide range of vectors.