Quantifying plant species diversity in a Natura 2000 network: Old ideas and new proposals

Assessing the effects of the spatial components on species diversity in a network of protected areas represents an important step for assessing its conservation “capacity”. A clear evaluation on how α-, β-, and γ-diversity are partitioned among and within spatial scales can help to drive manager decisions and provide method for monitoring species diversity. Moving from these concepts, a probabilistic sample of plant species composition was here applied for quantifying plant species diversity within the Sites of Community Importance (SCIs) of the Natura 2000 network in the Siena Province. All analyses were performed separately for all species and those species defined as “focal” (included in regional, national or continental “red” lists). The results indicated that species richness of the SCIs differed from one location to another one independently from the sampling efforts. Diversity partitioning indicated that most of the flora diversity within the network was given by larger-scale β-diversity, i.e. the differences in species composition among SCIs. β-diversity was then decomposed in two components: β_Area (due to the differences in area among SCIs) and β_Replacement (due to the compositional differences across SCIs). β_Area was particularly important for all species, while β_Replacement was the most important factor for focal species. The consequent implications for monitoring and nature conservation strategies are discussed.     

太白山南坡蝗虫群落数量分类及相似性分析

应用数量分类及相似性方法对秦岭太白山南坡蝗虫群落垂直分布样方资料进行了分析.结果表明,大体上可将太白山南坡蝗虫群落分为7种主要类型,即农耕带、常绿落叶阔叶混交林带、辽东栎杂木林带、桦木林带、冷杉林带、落叶松带、高山草甸带.太白山蝗虫群落垂直分布规律明显,其中高海拔的蝗虫种类数明显低于中低海拔.但低海拔的农耕带因人为干扰大,植被较单一,蝗虫的优势度和密度大,种类数较少.     

DCA、CCA和DCCA三种排序方法在中国草地植被群落中的应用现状

排序是用来分析植被与环境之间生态关系的重要手段。该文主要是对除趋势对应分析（DCA）、典范对应分析（CCA）和除趋势典范对应分析（DCCA）这三种排序方法进行总结，讨论它们在中国草地植被群落研究中的应用现状，并得出除趋势对应分析与聚类分析结合使用效果比较好，主要是用来揭示群落之间的关系，并且在实际的应用中也比较多，而典范对应分析和除趋势典范对应分析在揭示种与环境关系方面具有明显的优势，但是由于某些条件的限制，在实际研究中应用的比较少。可见这几种排序方法在实际应用中具有一定的优势，所以应该加强这方面的应用，更加深入的研究草地植被群落，以期对草地生态学及草地植被群落生态关系的研究工作发挥重要的借鉴作用。     

川西北不同沙化程度草地土壤细菌群落特征

研究川西北不同沙化程度草地（未沙化草地、轻度沙化草地、中度沙化草地、重度沙化草地）土壤细菌多样性和群落结构特征,利用Illumina二代高通量测序技术MiSeq对土壤细菌的16 SrRNA V₃—V₄可变区进行测序,研究土壤细菌多样性、物种组成和丰富度,并结合土壤理养分探讨影响细菌群落结构的环境因素,对发挥土壤潜在肥力,了解土壤健康状况,实现该区植被的管理与可持续利用有着重要的意义。结果表明:（1）不同沙化草地土壤养分具有明显差异,依次表现为:随着沙化程度的增加,土壤pH值逐渐增加,而土壤有机碳、全氮、全钾、碱解氮和速效磷逐渐降低;（2）不同沙化程度草地土壤样品中共检测到细菌的32个门,65个纲,169个目,优势菌门为变形菌门（Proteobacteria）、放线菌门（Actinobacteria）、酸杆菌门（Acidobacteria）、绿弯菌（Chloroflexi）、浮霉菌门（Planctomycetes）,主要的优势菌纲为放线杆菌纲（Actinobacteria）、α-变形菌纲（α-Proteobacteria）、酸杆菌纲（Acidobacteria）、β-变形菌纲（β-Proteobacteria）、浮霉菌纲（Planctomycetacia）,与沙化草地相比,未沙化草地优势菌主要是变形菌门（Proteobacteria）和放线菌门（Actinobacteria）;（3）随着沙化程度的增加,OUT数目、Chao指数、Ace指数、Shannon指数逐渐减小,其中不同沙化草地土壤细菌覆盖率和Simpson指数差异不显著（p > 0.05）;（4）冗余分析和Pearson相关性分析表明,土壤pH值、土壤有机碳（SOC）和全氮（TN）是土壤细菌群落结构和多样性的主要影响因子。     

重金属复合污染下红壤微生物活性及其群落结构的变化

在室内培养条件下,应用4因素5水平二次正交回归旋转组合设计方案,对重金属复合污染红壤的微生物活性及群落功能多样性进行了研究。结果表明,在Cu、Zn、Pb、Cd复合污染生境中重金属的微生物毒性效应发挥主要由Cd、Cu两元素决定,其生物毒性顺序表现为:Cd>Cu>Zn>Ph,红砂泥中表现较为突出。与单一镉、单一铅污染处理相比,重金属复合污染对供试红壤微生物生物活性及其群落功能多样性的影响并非仅仅表现出简单的加和作用,同时还存在协同作用和拮抗作用。典型相关分析显示,红壤微生物活性与重金属含量之间关系密切,第一对典型变量的相关系数r达0.885 8、0.932 8,均达极显著水平(p<0.001), 说明重金属复合污染与红壤微生物间存在较为稳定的数量反馈机制,红壤总体微生物活性指标能较好地反映供试红壤重金属复合污染状况,可作为重金属污染红壤环境质量评价及量化分类的有效指标。     

Differences in the diversity of oribatid mite communities in forests and agrosystems lands

A field study was conducted in the province of Burgos (Castile, NW of Spain) to assess the role and influence of the different anthropic use of soil on the oribatid mite communities (Acari, Oribatida).Soil samples from 20 representative soil sites of the Castilian upland steppes, with cultured, pastureland or forest soil uses, were taken in spring and autumn 2000. Thereafter, soil samples were analysed in terms of their mesofaunal biodiversity, measured using the real and relative diversity of the oribatid mite communities.Collected individuals were identified to species level, being altogether 111 Oribatid species. Results from communities' ordination analysis showed clear gradients based on community variables. One of these was defined by plots with high values of diversity and species richness which correspond to the less anthropic natural soils, mainly oak forest. In contrast, the most anthropic agrosystems soils, including extensive cereal crops, most of them receiving only mineral fertilisation or having human management, were placed in opposite gradients. Differences in biodiversity between crop lands and natural soils were also confirmed by ANOVA. The seasonality, measured in terms of difference between spring and autumn plots, played a minimum role in explaining differences of diversity. Nevertheless autumn diversity values were slightly higher than those of spring, except for crops.     

中国东北地区白桦林植被生态学的研究──桦属植物与中国白桦林的地理分布

阐明了桦属植物在中国的地理分布特点,白桦（ＢｅｔｕｌａｐｌａｔｙｐｈｙｌａＳｕｋ．）的分类学位置及分布,以白桦及其变种为优势种的森林植被的水平与垂直分布;分析了桦属植物在全球范围内组成植被的特征：①桦属狭域种是北方林线的重要组分．②桦属植物是植被动态中比较活跃的组分,表现为桦属植物多是次生植被的先锋组分,多为超地带性植被的组分,桦属广域分布种多是植被交错区的组分．     

冬油菜与杂草对长期不同施肥的差异性适应

研究长期水旱轮作条件下,施肥模式对田间冬油菜、杂草、土壤养分及冬油菜–杂草空间分布的影响,为长江流域冬油菜轻简化生产提供依据。2011年在湖北省粮油主产区——江汉平原布置水稻–冬油菜轮作肥效定位试验。2016年冬油菜收获期,调查农田杂草群落多样性和分析油菜–杂草–土壤养分三者状况。结果表明,长期土壤养分亏缺会显著影响油菜–杂草的生长和空间分布、形成不同的杂草优势群落。平衡施肥(NPK处理)有助于增加冬油菜根茎粗、有效分枝数、角果数和最终产量,降低杂草总生物量,提高杂草群落多样性Shannon-Wiener指数。与NPK处理相比,–N、–P和–K均会不同程度地降低籽粒、茎秆、角壳和杂草的养分吸收量,尤以–P处理降幅最为明显。与土壤养分含量的初始值相比,长期不施用化肥会引起土壤氮磷钾有效含量下降,尤其对于土壤钾,现有平衡施肥措施不足以弥补农田钾素亏缺,应重视秸秆还田的补钾效果。总之,长期科学的农田养分管理与调控措施,不仅可以降低杂草对冬油菜的危害、增强生物多样性和形成良性的油菜-杂草竞争环境,也有利于减少化学药剂使用、推动冬油菜的轻简化生产。     

陕西杨凌示范区城镇化发展分析——以李台街道办为例

“十二五”时期,如何推进城镇化进程中的农村社区发展,是实现经济欠发达地区转型跨越发展的一个重大课题.2011年末,陕西杨凌李台街道办辖区耕地已被全部征用,农业户籍因村转居全部转为城镇居民户籍.2011年村转居社区居民人均纯收入9 156元,城市居民人均可支配收入25 999元.该研究运用农业经济学、农业社会学、农业地理学、农业区划学、发展经济学等工具,以陕西杨凌李台街道办为研究对象,介绍了李台街道办城镇化的发展状况,总结了农村城镇化的经验与教训,为类似农村社区在城镇化道路的发展提供新途径.     

Positionality and protocol in field research: Undertaking community‐based investigations in Samoa

This article considers the experiences of a Samoan female geographer undertaking community‐based field research in her home country, and identifies some lessons for researchers working in similar circumstances. The paper suggests that ethical behaviour in research is ‘place‐specific’, and there is therefore a need to employ culturally sensitive and ‘location‐specific’ methodologies when undertaking community‐based research fieldwork. For the lead researcher, growing up in Samoa played a significant role in gaining an understanding of a set of robust and effective procedures to evaluate citizens' resilience to climatic and other environmental challenges. Fluency in everyday and more formal local languages, and awareness of local differences, each with multi‐layered connections to local communities, understanding cultural nuances and practising respect for va tapuia [sacred space or relationships] protocols, together facilitated the process of knowledge acquisition and helped to confirm the validity of the conclusions derived from the study.