Spatial correlation between the prevalence of transmissible spongiform diseases and British soil geochemistry

Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurological conditions affecting a number of mammals, including sheep and goats (scrapie), cows (BSE), and humans (Creutzfeldt-Jakob disease). The diseases are widely believed to be caused by the misfolding of the normal prion protein to a pathological isoform, which is thought to act as an infectious agent. Outbreaks of the disease are commonly attributed to contaminated feed and genetic susceptibility. However, the implication of copper and manganese in the pathology of the disease, and its apparent geographical clustering, have prompted suggestions of a link with trace elements in the environment. Nevertheless, studies of soils at regional scales have failed to provide evidence of an environmental risk factor. This study uses geostatistical techniques to investigate the correlations between the distribution of TSE prevalence and soil geochemical variables across the UK according to different spatial scales. A similar spatial pattern in scrapie and BSE occurrence is identified, which may be linked with increasing pH and total organic carbon, and decreasing iodine concentration. However, the pattern also resembles that of the density of dairy farming. Nevertheless, despite the low spatial resolution of the TSE data available for this study, the fact that significant correlations are detected indicates there is a possibility of a link between soil geochemistry, scrapie, and BSE. It is suggested that further investigations of the prevalence of TSE and environmental exposure to trace metals should take into account the factors affecting their bioavailability.     

上海崇明县植被覆盖度动态变化遥感监测研究

植被覆盖度是用于描述和评价生态系统的重要参数。基于1989、2001、2006年的TM/ETM+遥感数据,以上海市崇明县为研究区域,利用改进的像元二分模型,估算出不同时期内崇明县的植被覆盖度,并对其变化进行了定量分析。结果表明:1989-2001年,植被覆盖度负向变化地表约10.17%,正向变化约20.58%,乡镇和湿地区域正向变化的面积大于负向变化,农场区域则相反;2001-2006年,负向变化约29.1%,正向变化约12%,农场和湿地区域正向变化的面积大于负向变化,乡镇区域则相反,并且随着城市化进程的深入,各土地用地类型的植被覆盖度变化在一定程度上都呈现出生态退化的趋势。     

Identifying robust strategies for assisted migration in a competitive stochastic metacommunity

Assisted migration (AM) is the translocation of species beyond their historical range to locations that are expected to be more suitable under future climate change. However, a relocated population may fail to establish in its donor community if there is high uncertainty in decision-making, climate, and interactions with the recipient ecological community. To quantify the benefit to persistence and risk of establishment failure of AM under different management scenarios (e.g., choosing target species, proportion of population to relocate, and optimal location to relocate), we built a stochastic metacommunity model to simulate several species reproducing, dispersing, and competing on a temperature gradient as temperature increases over time. Without AM, the species were vulnerable to climate change when they had low population sizes, short dispersal, and strong poleward competition. When relocating species that exemplified these traits, AM increased the long-term persistence of the species most when relocating a fraction of the donor population, even if the remaining population was very small or rapidly declining. This suggests that leaving behind a fraction of the population could be a robust approach, allowing managers to repeat AM in case they move the species to the wrong place and at the wrong time, especially when it is difficult to identify a species’ optimal climate. We found that AM most benefitted species with low dispersal ability and least benefited species with narrow thermal tolerances, for which AM increased extinction risk on average. Although relocation did not affect the persistence of nontarget species in our simple competitive model, researchers will need to consider a more complete set of community interactions to comprehensively understand invasion potential.     

基于空间聚类分析的中国旅游业碳排放效率

旅游业碳排放效率是考量旅游经济增长与生态环境关系的重要指标,对旅游业碳排放效率的有效测度和分析是实现旅游业节能减排与可持续发展的基础支撑.采用“自下而上”法核算2001—2015年我国旅游业能源消耗量与碳排放量（不含港澳台及西藏自治区数据,下同）;继而运用非期望产出SBM模型对旅游业碳排放效率进行测度,并通过空间自相关分析揭示其空间特征;最后采用Malmquist指数（MI）评估旅游业碳排放效率的动态趋势.结果表明:①研究期内我国旅游业总体碳排放效率较低,平均水平为60%;各年度达到最佳生产前沿面（旅游业碳排放效率值为1）的省(市、自治区)(简称“省区”)数量较少,绝大多数省区的碳排放效率具有较大改善空间;旅游业碳排放效率水平存在明显的省际差异;东、中、西部地区的效率存在梯度差,形成“东高西低”的空间格局.②Moran's I指数和LISA聚类图显示,各省区旅游业碳排放效率存在明显的正向空间相关性,在空间分布上呈现出显著的地理聚集特征,形成“高—高”型与“低—低”型聚集区,空间联动格局尚未形成.③2001—2015年MI均在1以上（2004年除外）,且总体平均值高达1.195,体现出持续改善的态势;各省区碳排放效率的提升来源于技术进步与技术效率双重贡献,其中,技术进步是促进旅游业碳排放效率提升的主要贡献因素.研究显示,我国旅游业碳排放效率的空间分布不均衡,但整体呈现持续上升的态势,各省区在依赖技术进步提高碳排放效率的同时,要注重全局空间联动格局的形成,最终实现低碳旅游业的协调发展.      

黄河三角洲人工草场群落土壤盐分动态集成预报模型及其应用

提出了以ＧＭ（１,１）模型拟合发展的趋势、傅里叶变换撮周期分量ＡＲ（ｐ）模型模拟随机过程的集成预报模型,并用于黄河三角洲人工草场群落土壤盐分的定量研究中,经理论和应用检验证明：该模型能以较高的精度模拟或预报土壤盐分在较长时期内的动态变化过程,方法简单,计算工作量小,并优于传统的单一预报模型。     

湖南省高效生态农业模式与综合技术研究总结

文章总结了湖南省10年来推行高效生态农业模式和推广综合农业技术的理论和实践,以及取得的效益。经过10年的努力,5个试点县的生态环境质量得到了显著改善,农业与农村经济得到了巨大发展;累计推广应用面积3.2663106 hm2,新增产值50.90亿元。     

四川喇叭河自然保护区的两栖爬行动物垂直分布及保护区型式

四川省喇叭河自然保护区已知分布有39种两栖爬行动物，本文对在该地区海拔700-2600m的地段划分为19个小带，并对其物种多样性的分布特点和分布规律进行了研究．结果表明：两栖爬行动物在保护区内具有明显的垂直分布现象，海拔900-1099m过渡带和2100-2299m过渡带是该地物种保护的关键地区，该区域具有物种丰富、区系复杂和生态脆弱等特点；因此，在规划建设和旅游开发过程中应避免对该区域的影响，同时保护区的规划应遵循物种多样性的分布规律，合理设计保护区的空间格局，初步提出了多核心、多层次的保护区新型式．图5表2参16     

Life History as a Predictor of Salamander Recovery Rate from Timber Harvest in Southern Appalachian Forests,U.S.A

Forest management often represents a balance between social, economic, and ecological objectives. In the eastern United States, numerous studies have established that terrestrial salamander populations initially decline in abundance following timber harvest, yet the large‐scale and long‐term consequences are relatively unknown. We used count data from terrestrial survey points to examine the relation between salamander abundance and historic timber harvest while accounting for imperfect detection of individuals. Overall, stream‐ and terrestrial‐breeding salamanders appeared to differ by magnitude of population decline, rate of population recovery, and extent of recolonization from surrounding forest. Specifically, estimated abundance of both species groups was positively associated with stand age and recovery rates were predicted to increase over time for red‐legged salamanders (Plethodon shermani) and decrease in stream‐breeding species. Abundance of stream‐breeding salamanders was predicted to reach a peak by 100 years after timber harvest, and the population growth rate of red‐legged salamanders was predicted to undergo a significant increase 100 years after harvest. Estimated abundance of stream‐breeding salamanders in young forest stands was also negatively associated with the distance to adjacent forest, a result that suggests immigration has a role in the recovery of these species. Our results indicate that salamander abundance in young forest stands may be only modestly lower than in more mature forest but that full recovery from timber harvest may take a substantial amount of time and that species life history may affect patterns of recovery. Historia de Vida como un Vaticinador de la Tasa de Recuperación de una Salamandra a la Colecta de Madera en los Bosques del Sur de los Apalaches, E.U.A     

Effects of Exurban Development and Temperature on Bird Species in the Southern Appalachians

Land‐use dynamics and climatic gradients have large effects on many terrestrial systems. Exurban development, one of the fastest growing forms of land use in the United States, may affect wildlife through habitat fragmentation and building presence may alter habitat quality. We studied the effects of residential development and temperature gradients on bird species occurrence at 140 study sites in the southern Appalachian Mountains (North Carolina, U.S.A.) that varied with respect to building density and elevation. We used occupancy models to determine 36 bird species’ associations with building density, forest canopy cover, average daily mean temperature, and an interaction between building density and mean temperature. Responses varied with habitat requirement, breeding range, and migration distance. Building density and mean temperature were both included in the top occupancy models for 19 of 36 species and a building density by temperature interaction was included in models for 8 bird species. As exurban development expands in the southern Appalachians, interior forest species and Neotropical migrants are likely to decline, but shrubland or edge species are not likely to benefit. Overall, effects of building density were greater than those of forest canopy cover. Exurban development had a greater effect on birds at high elevations due to a greater abundance of sensitive forest‐interior species and Neotropical migrants. A warming climate may exacerbate these negative effects. Efectos del Desarrollo Exurbano y de la Temperatura sobre Especies de Aves en las Apalaches del Sur     

农业非点源模型--AGNPS概述

非点源污染在国内外已越来越受到关注，其中农业非点源又占相当大的份额。由于非点源污染产生机制的特殊性。导致实地调查和试验研究不易实行。故而数学模型方法在这一领域尤其能够体现出它的优点，对它的研究也受到了学术界越来越多的重视。目前，国外已开发出了大量的非点源数学模型，而其中A3NPS模型是应用较为广泛者之一，并已在我国得到了应用。基于此，文中介绍了AGNPS模型的基本结构，主要包括水文、侵蚀和化学污染物的迁移三部分。自从该模型被建立以来，国外已对它进行了大量的研究，本文从研究最多的几个方面进行了讨论，即计算网格的优化、模型输入输出与GIS的结合以及模型的风险性等，以期为在我国的具体应用提供一定的参考。