Long-term benthic population changes (1920–1930s-present) in the Barents and Kara Seas     

O. A. Kiyko  V. B. Pogrebov 《Marine pollution bulletin》1997,35(7-12):322-332

Bottom sediment was analysed, via grab, trawl and underwater photography in 1991–1992 in the Barents, White, Kara, Norwegian and Greenland Seas, and the large scale features of macrobenthos distribution are described. The maps of alpha-diversity, biomass and trophic zone distribution on the investigated shelf are presented. Statistical assessment of the bottom community structure changes during the last 60–70 years for the Barents Sea area is presented. It is shown that on regional and transregional levels the researched communities are of natural undisturbed character and that the revealed changes may be both the result of natural processes or sampling errors. Local disturbances of benthos composition and structure, supposedly caused by man, are found to be rare not far from the Novaya Zemlya and Murman coasts.  相似文献   

Conceptual study — An improved method to assess acidification in German streams by using benthic macroinvertebrates     

Ulrich Braukmann  Regina Biss 《Limnologica》2004,34(4):433-450

The present study is based mainly upon the authors' hydrochemical and hydrobiological studies of small silicate streams in South-West Germany, principally in the Black Forest and the Odenwald.

The aim of the paper is the adaptation of a practically proven four-level biological classification system of different degrees of acidity using benthic maroinvertebrates to a five-level system of acidification of mainly upland streams with low buffer capacity. The main reason for such a five-class system is the Water Framework Directive of the European Union (EU WFD), which lays down a five-level classification system for the assessment of the ecological quality of waters.

The biological method of assessing the state of acidity for evaluation of the degree of anthropogenic acidification under the directive, and principles of the EU WFD, are also described. A list of 278 taxa of the macrozoobenthos has been reclassified from a four-level system to a five-level biological indication system, based upon the authors' scientific expertise and the latest references from literature of different acid sensitive areas in Germany.  相似文献   

Soil–vegetation relationships in a coastal desert plain of southern Sinai, Egypt     

Monier M. Abd El-Ghani  Wafaa M. Amer 《Journal of Arid Environments》2003,55(4):607-628

The present study provides an analysis of soil, vegetation types as well as structure and species distribution in 19 sites in El-Qaa plain along the Gulf of Suez (south Sinai, Egypt), and focuses on the environmental factors that control the species distribution. A total of 203 species belonging to 39 families of the vascular plants are recorded. Asteraceae, Fabaceae, Chenopodiaceae and Poaceae are the largest families. Grasses constitute only 9% of the recorded species, while the woody perennials (shrubs and sub-shrubs) are highly dominated (46%). Therophytes and chamaephytes are the most frequent, denoting a typical desert life-form spectrum. Floristic composition in the different geomorphologic landscape units showed differences in species richness. The highest mean species richness of 19.7±1.7 is recorded in the wadi channels. The lowest species richness values are recorded in the coastal shore and playas (6.0±1.4) and in the alluvial fans (mean of 8.4±1.6 species). Chorological analysis revealed that 46% of the studied species are uniregional, being native to the Saharo-Arabian region. On the other hand, about 50% of the recorded species are biregional and pluriregional, extending their distribution all over the Saharo-Arabian, Sudano-Zambezian, Irano-Turanian and Mediterranean regions. Classification of the vegetation is analysed using two-way indicator species analysis (TWINSPAN) techniques resulted in the recognition of five vegetation groups, each of definite vegetation and soil characters, and could be linked to a specific geomorphologic unit. Capparis spinosa var. spinosa occupied the terraces, Cornulaca monacantha, Convolvulus lanatus and Deverra tortuosa inhabited the alluvial plains, Launaea nudicaulis and Artemisia judaica characterized the wadi channels, Acacia tortilis subsp. raddiana and Leptadenia pyrotechnica characterized the alluvial fans and Tamarix nilotica, Zygophyllum album and Nitraria retusa on the playas and the coastal shore. Ordination techniques as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) are used to examine the relationship between the vegetation and studied soil parameters. Nine soil variables are included: electrical conductivity, pH, calcium carbonate, gypsum, organic matter, gravel, fine soil fractions and soil saturation percentage. Analysis with DCA gave results similar to CCA, suggesting that there is a relatively high correspondence between vegetation and soil factors. DCA axis 1 showed significant positive correlation with CaCO₃, pH, soil saturation and organic matter, and interpreted as a calcium carbonate—soil saturation gradient. DCA axis 2 showed significant correlation with pH, gypsum and electric conductivity, and interpreted as an electric conductivity—gypsum gradient. Application of CCA indicated that soil surface sediment, CaCO₃, soil saturation, pH and organic matter are the main operating edaphic gradients in the area. These gradients are related closely to the first three canonical axes, and accounted for 67% of the species–environment relationship among the sites.  相似文献   

Book Reviews     

《Singapore journal of tropical geography》2002,23(2):236-243

Books reviewed:
Maruja M.B. Asis, (ed.) The Philippines as Home: Settlers and Sojourners in the Country.
Hans Gooszen, A Demographic History of the Indonesian Archipelago, 1880–1942.
Karin Bras, Image-Building and Guiding on Lombok: The Social Construction of a Tourist Destination.
K.S. Chon, (ed.) Tourism in Southeast Asia: A New Direction.  相似文献   

黔南石炭纪生物礁造礁群落的基本特征   总被引：10，自引：1，他引：10       下载免费PDF全文

巩恩普张永利  关长庆孙宝亮 《地质学报》2007,81(9):1183-1194

黔南紫云猴场扁平村发育有石炭纪全球罕见的大规模典型的后生动物骨架礁,该礁体的主体部分由大型笙状群体四射珊瑚Fomitchevella建造而成,下部发育点礁层,形成了罕见的、独特的石炭纪礁体类型。对该礁体的造礁群落详细研究,尤其是对Fomitchevella造礁群落的研究后发现,造礁群落内生物结构、物理结构决定了群落的整体面貌而造礁群落的营养结构是维持这种面貌持续发展的主要因素,从而这3个方面共同作用来达到复杂的造礁生态体系的平衡。在礁体的整个发展过程中,后生动物造礁群落的存在与发展是至关重要的,它们维持了一个相对复杂的造礁生态体系的平衡发展。群落的整体面貌、生态体系都是由群落内的关键种所决定的,如果将群落内起到核心作用的物种从群落内移走,那么群落的性质,生物的组成和功能都将发生变化。  相似文献   

Localising privatisation, disconnecting locales - Mechanisms of disintegration in post-socialist rural Russia     

Peter Lindner 《Geoforum》2007,38(3):494-504

Soviet collectives in general and especially the kolkhozes in rural areas were much more than merely production units. They regulated a significant part of everyday life in the villages and thus have to be seen as all-embracing social institutions, constituting the bedrock for rural communities. Relying on the homogenising effect of the kolkhoz-mechanism most authors who analyse the process of transformation in the Post-Soviet Russian countryside highlight the failures of privatisation and consequently presume continuity and not change. This paper argues, first, that in view of the weakness of the central state in the 90s a considerable leeway existed at the local level for different ways and degrees to implement the reform legislation and, second, that the concrete outcomes of the restructuring can only be adequately understood focusing on interests and power relations on the micro level rather than dealing with farms as such as the ‘acting units’.The common vantage point for most of the kolkhozes was an “alliance for the locale” between management and workers. It had its roots in the fear to become “slaves on one’s own land” if non-local investors would be allowed to buy agricultural land, to remain without infrastructure like streets, water supply and kindergartens if the kolkhoz would be divided up and to lack the machinery to work the private plots without the support of the farms. But beyond this consensus the chairmen of the collective farms could rely on a bulk of different allocative and authoritative resources to stage-manage privatisation. This introduced a highly ‘individual’ moment in the process and led to rising disparities and an increasing disintegration of rural Russia in the 1990s. Using a farm in southern Russia as an example the closer look at these resources and the “failed privatisation” unveils, that not continuity, but hybrid amalgamations of old and new characterise the Post-Soviet Russian countryside.  相似文献   

Social Cohesion; Is it sufficient? Migrant communities in two disadvantaged neighborhoods in Istanbul     

Hürriyet G. Ögdül 《GeoJournal》2000,51(4):321-328

Planners assume that old neighbourhoods have an atmosphere in which social relations can easily flourish. They also regard the strong social ties within a neighborhood as the guarantee for the success of housing rehabilitation. This article argues that existence of social cohesion in a neighbourhood is not necessarily an advantage in a process of modernisation and rehabilitation. In some cases the community may constitute a closed `island' especially in places where communities have historically inherited an hierarchical character. The article is based on a recent research project dealing with urban communities in inner city areas of Istanbul, especially those containing migrant populations which seemingly have strong community ties. The historical background of the community from the Ottoman period is examined in the first part of the article. The roots of the community as a territorial administrative unit (mahalle) and its modification in contemporary migrant communities are analysed. The second part of the article presents the results of two case studies. One of the case studies is a social housing district where the migrant community is mixed and social relations with the rest of the city are relatively well developed. The other case study area is an historical district where strong social ties create an introverted character of the community in spite of its central location. The result of the study reveals that urban `communities' in a city like Istanbul have both negative and positive aspects. Primarily it is important to assess and understand the degree of `opennes' of the community to the outer world. In any action to be taken planners should look not only inside the community, but also at its 'outer' relations.  相似文献   

法国阿尔卑斯山(Mt.Alps,France) 溪流型喀斯特瀑布水生苔藓植物群落生态研究   总被引：6，自引：4，他引：2  

张朝晖  陈家宽  艾伦．培特客斯 《中国岩溶》2007,26(1):24-30

对法国阿尔卑斯山(M t. Alps, France) 6个溪流型喀斯特瀑布水生苔藓植物群落进行了研究。报道典型瀑布水生苔藓群落14个,苔藓植物种类由11科16属20种(含变种亚种) 组成; 生殖系统由雌雄异株( Dio ecious, 95% )和雌雄同株异苞( Auto ecious, 5% )两种类型构成,无性繁殖是繁殖的主要方式; 区系地理成分含北温带分布( 60% ) 、欧洲- 北美分布( 10% )、旧世界温带分布( 5% )和世界广泛分布( 25% ) 等4种成分; 生活型含高丛集型( 20% )、矮丛集型( 10% )、交织型( 60% )和平铺型( 10% ) 4种类型。根据喀斯特沉积环境特征, 划分瀑布水生苔藓群落为峡谷瀑布苔藓群落、温泉瀑布苔藓群落、瀑布水帘洞苔藓群落、悬崖瀑布苔藓群落和悬崖季节性瀑布苔藓群落等5种生态类型。法国阿尔卑斯山溪流型瀑布生物喀斯特沉积物具有分布广泛,但沉积规模较小的特点。   相似文献   

法国阿尔卑斯— 罗讷(Rhone-Alps)岩溶洞穴弱光带苔藓植物群落研究   总被引：23，自引：11，他引：12  

张朝晖  艾伦· 培特客斯 《中国岩溶》2001,20(3):236-240

报道了法国阿尔卑斯-罗讷( Rhone-Alps )地区3个岩溶洞穴苔藓植物群落研究结果。记载典型洞穴苔藓群落11个,苔藓植物种类8科12属15种(含变种); 区系地理成分含北温带分布(46. 66%)、温带欧洲分布(6. 67% )、欧洲-亚洲分布(6. 67%)、欧洲-北美分布(13. 33%)和世界广泛分布(26. 67%) 5种成分; 生活型含高丛集型(20%)、矮丛集型(33. 33%)、交织型(40%)和平铺型(6. 67%) 4种类型。根据岩溶沉积环境特征,划分洞穴苔藓群落为钟乳石苔藓群落、洞壁钙华苔藓群落、洞底泉华苔藓群落和石灰土苔藓群落等4种生态类型。   相似文献   

The Community Economic Impacts of Large Wildfires: A Case Study from Trinity County,California     

Emily Jane Davis  Cassandra Moseley  Max Nielsen-Pincus  Pamela J. Jakes 《社会与自然资源》2014,27(9):983-993

Wildfires are increasing in severity and frequency in the American West, but there is limited understanding of their economic effects at the community level. We conducted a case study of the impacts of large wildfires in 2008 in Trinity County, California, by examining labor market, suppression spending, and qualitative interview data. We found that the 2008 fires had interrelated effects on several economic sectors in the county. Labor market data indicated a decrease in total private-sector employment and wages and an increase in public-sector employment and wages during the summer of 2008 compared to the previous year, while interviews captured more nuanced impacts for individual businesses.  相似文献