喀斯特地区长期草地利用制度对群落稳定性的影响

草地利用方式和混播组合对群落特性的长期影响不同。利用方式对白三叶(Trifolium repens)盖度没有显著影响,而混播组合与利用方式的交互作用影响显著。白三叶在宿营处理和刈割为主利用下的与鸭茅(Dactylis glomerata)混播中的比例最低,而在刈割利用和宿营处理的多年生黑麦草(Lolium perenne)组合中的盖度最高。混播组合对禾本科组分盖度影响不显著,但利用方式和交互作用有显著的作用,长期放牧绵羊的混播草地多年生黑麦草很少。混播组合对杂草密度、盖度和多样性指数的影响不明显,而利用方式和交互作用显著地影响杂草盖度和多样性指数。放牧草地中的杂草密度高于刈割草地的,其中放牧利用的白三叶/多年生黑麦草草地最高。放牧牛的草地杂草密度较少,而放牧绵羊的草地杂草较多。白三叶、禾本科牧草以及杂草的密度都显著地受混播组合、利用方式及其交互作用的影响,说明密度是一个敏感的指标。     

宁夏新垦区昆虫群落生态演替及有害种预警系统研究

以宁夏中宁县长山头、大战场（荒漠半荒漠）、灵武市狼皮子梁（沙漠）、青铜峡市渠口农场（草原化荒漠）３类垦前环境及其垦后不同耕作年限（１－１５ａ）农田昆虫群落演替进行了系统调查与研究,事理鉴定出昆虫１１目７９科２０４种,按其分布和种群动态变化划分为原生性种类、共生性种类、继生性种类和迁入性种类４个生态型类群。在此基础上研究了不同目、不同营养型类群和不同生态型类群昆虫多样性变化及时间系列演替,发现随着荒     

伊犁河谷北坡野果林群落结构及其与环境的关系

结合野外植被调查,在获取较为详细的生境数据基础上,探讨伊犁河谷北坡野果林群落与环境因子之间的定量关系.TWINSPAN和去趋势典范对应分析(DCCA)的结果表明:1)在伊犁河谷北坡野果林群落分布地段,地形因子、养分和水分条件是群落生境的基本因子;2)海拔因子指示出研究区野果林群落最基本的分化,说明海拔条件是制约研究区植物群落分布的最重要的因子;3)土壤表层水分状况与海拔关系较密切,反映了草本层群落所受到的水分条件影响;4)养分状况的差异,除了说明生境条件本身的差异外,也在一定程度上指示了群落现在生境的养分状况,受人为的影响较大.总之,在山地复杂的地形条件下,群落生境条件的差异非常显著,海拔、土壤含水率、全氮、坡向和pH值的组合,影响并控制着研究区各群落分布格局的形成.     

长春市不同土地利用生境土壤昆虫幼虫群落组成与生态分布

对长春市郊区天然次生林、市内公园风景林、郊区防护林和农田等土地利用生境进行土壤昆虫幼虫调查,研究土地利用差异对土壤昆虫幼虫群落特征的影响。研究区共捕获土壤昆虫幼虫35科411只,其中鞘翅目幼虫14科319只,双翅目幼虫13科64只,鳞翅目幼虫8科28只。研究结果表明:不同土地利用生境土壤昆虫幼虫群落组成与生态分布存在差异,防护林和农田土壤昆虫幼虫的类群数和个体密度显著减少;除农田外,其他生境土壤昆虫幼虫群落个体密度和类群数主要集中分布在0～5cm土壤层,生境凋落物的移除对土壤昆虫幼虫群落组成影响不明显;此外,鞘翅目、双翅目和鳞翅目幼虫对土地利用和植被类型变化的响应也不同。     

环境微生物群落分析的T-RFLP技术及其优化措施

末端限制性酶切片段长度多态性分析(terminal restriction fragment length polymorphism, T-RFLP)是近年来发展起来的、不依赖于培养的微生物群落分析方法之一.由于其在微生物群落结构分析方面的特点,包括分辨率高、易于实现自动化及互联网海量数据共享等优势,自1997年最先被报道以来得到了广泛的应用,成为环境微生物群落分析的最强有力的工具之一.本文详细介绍了T-RFLP技术的原理,并从环境样品群落DNA的提取、引物设计和PCR扩增、限制性酶切、电泳分离检测和T-RFLP图谱解析等5个方面讨论了用该技术解析环境微生物群落的方法和技巧,简述了近8 a来国外T-RFLP技术在群落分析中的研究进展.类似于其他的分子微生物生态学技术, T-RFLP也有自身的缺陷,因此重点分析了该技术的局限性及相应的解决办法.图2表1参62     

Biofilm structure and its influence on clogging in drip irrigation emitters distributing reclaimed wastewater

Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy (SEM) revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides (EPS) and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide and phospholipid fatty acids (PLFAs) showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coefficient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path (Emitter C) had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.     

社区防灾减灾对策的复杂性科学问题

"社区研究"已有约150年的历史,社区的防灾减灾对策是一个综合性的科学问题。充分发挥社区的防灾减灾功能十分必要,确立社区防灾减灾最优对策在中国的现代化建设和可持续发展战略中具有重要意义。利用复杂性科学的理论和模型来处理社区的防灾减灾对策问题,是系统科学或复杂性科学中的一个有意义的发展方向。本文提出并分析了社区防灾减灾对策研究中的4个问题,即如何界定社区防灾减灾应急管理的角色和方向;何为防灾减灾安全社区;如何预警突发性灾难事件;社区防灾减灾系统是如何自组织的。本文引入复杂性科学理论对社区的防灾减灾对策进行了研究,讨论了复杂性科学应用于社区防灾减灾对策的理论框架。     

Off-grid: community energy and the pursuit of self-sufficiency in British Columbia's remote and First Nations communities

Remote or off-grid communities in Canada primarily rely on diesel generators for the provision of their electricity. Often surrounded by potential renewable resources, they are characterised as the low-hanging fruit of greenhouse gas mitigation strategies. While much is said about the promises of community energy projects, as well as technologies and policy mechanisms for addressing the needs of these communities, little attention has been paid to what communities, themselves, might want for their energy projects and what the implications of those desires might be for both technology development and community energy policies. This paper aims to fill this gap by exploring the on-going energy pursuits of a number of remote First Nations communities in British Columbia. It identifies a desire for community self-sufficiency as a primary motivation for engaging with energy projects on the part of the communities and discusses the various meanings and implications of self-sufficiency in the context of community energy projects. These meanings and implications primarily include the two dimensions of material self-sufficiency and political self-determination, the latter of which suggests a view of community energy projects as processes of decolonisation among First Nation communities in British Columbia. It then suggests that the pursuit of this goal is somewhat incongruent with the approach that government and industry have taken in addressing community energy, especially the way in which remote communities are viewed as the low-hanging fruit of various sustainability projects.     

Empirical Trials of Plant Field Guides

We designed 3 image‐based field guides to tropical forest plant species in Ghana, Grenada, and Cameroon and tested them with 1095 local residents and 20 botanists in the United Kingdom. We compared users’ identification accuracy with different image formats, including drawings, specimen photos, living plant photos, and paintings. We compared users’ accuracy with the guides to their accuracy with only their prior knowledge of the flora. We asked respondents to score each format for usability, beauty, and how much they would pay for it. Prior knowledge of plant names was generally low (<22%). With a few exceptions, identification accuracy did not differ significantly among image formats. In Cameroon, users identifying sterile Cola species achieved 46–56% accuracy across formats; identification was most accurate with living plant photos. Botanists in the United Kingdom accurately identified 82–93% of the same Cameroonian species; identification was most accurate with specimens. In Grenada, users accurately identified 74–82% of plants; drawings yielded significantly less accurate identifications than paintings and photos of living plants. In Ghana, users accurately identified 85% of plants. Digital color photos of living plants ranked high for beauty, usability, and what users would pay. Black and white drawings ranked low. Our results show the potential and limitations of the use of field guides and nonspecialists to identify plants, for example, in conservation applications. We recommend authors of plant field guides use the cheapest or easiest illustration format because image type had limited bearing on accuracy; match the type of illustration to the most likely use of the guide for slight improvements in accuracy; avoid black and white formats unless the audience is experienced at interpreting illustrations or keeping costs low is imperative; discourage false‐positive identifications, which were common; and encourage users to ask an expert or use a herbarium for groups that are difficult to identify. Pruebas Empíricas de Guías de Campo de Plantas Hawthorne, Cable & Marshall     

The data not collected on community forestry

Conservation and development practitioners increasingly promote community forestry as a way to conserve ecosystem services, consolidate resource rights, and reduce poverty. However, outcomes of community forestry have been mixed; many initiatives failed to achieve intended objectives. There is a rich literature on institutional arrangements of community forestry, but there has been little effort to examine the role of socioeconomic, market, and biophysical factors in shaping both land‐cover change dynamics and individual and collective livelihood outcomes. We systematically reviewed the peer‐reviewed literature on community forestry to examine and quantify existing knowledge gaps in the community‐forestry literature relative to these factors. In examining 697 cases of community forest management (CFM), extracted from 267 peer‐reviewed publications, we found 3 key trends that limit understanding of community forestry. First, we found substantial data gaps linking population dynamics, market forces, and biophysical characteristics to both environmental and livelihood outcomes. Second, most studies focused on environmental outcomes, and the majority of studies that assessed socioeconomic outcomes relied on qualitative data, making comparisons across cases difficult. Finally, there was a heavy bias toward studies on South Asian forests, indicating that the literature on community forestry may not be representative of decentralization policies and CFM globally.