Influence of rural land use on streamwater nutrients and their ecological significance

Concentrations and loads of N and P fractions were examined for lowland rivers, the Wye and Avon, draining a range of representative agricultural land-use types in two major UK river basins. Data collected over a 2-year period demonstrated important diffuse agricultural source contributions to N and P loads in these rivers. Ground water provided a major source of total dissolved nitrogen (TDN) loads, whereas near-surface sources provided a major contribution to total phosphorus (TP) loads. In terms of aquatic ecology, concentrations of nutrients, at times of eutrophication risk (spring and summer low flows) were of key environmental and management significance. Agricultural diffuse sources provided the major source of long-term P loads across the two basins. However, the results demonstrated the dominance of point-source contributions to TP and SRP concentrations at times of ecological risk. Point sources typically ‘tip the balance’ of dissolved inorganic P (soluble reactive P, SRP) above the 100 μg l⁻¹ guideline value indicative of eutrophication risk. The significance of point sources for TP and SRP concentrations was shown by (a) the strong correlations between TP, SRP and B concentrations, using B as a tracer of sewage effluent, (b) the dominant contribution of SRP to TP concentrations and (c) the predominant pattern of dilution of SRP and B with flow. The clean Chalk streams draining low intensity grassland in areas of the Avon with sparse human settlement were oligotrophic and P limited with low SRP concentrations under spring and summer baseflows attributable to groundwater sources. The data provide important insights into the ecological functioning of different lowland stream systems. There was evidence of greater SRP losses and N-limitation in a stream which drains a pond system, demonstrating the importance of longer water residence times for biological nutrient uptake.     

2001—2002年粤东柘林湾浮游植物的生态学研究

2001年7月-2002年7月对粤东赤潮重灾区柘林湾进行的浮游植物周年调查表明,柘林湾共有浮游植物68属183种.其中硅藻为最优势类群,共51属143种,占总种数的 77.8%;甲藻11属34种;其它浮游植物类群6属6种.调查海区浮游植物群落的种类丰富度、细胞密度、生物多样性和均匀度的平面分布均表现为湾外高于湾内和湾内外侧高于湾内内侧的基本格局,但黄冈河河内浮游植物群落的构成却呈现种类少而密度高的特点.调查期间浮游植物的总细胞数年均值为16.9×104cells/L,周年变动模式为双峰型(高峰位于8月和4月).与上一个周年调查(2000年5月-2001年5月)的总细胞数年均值(36.0×104cells/L)和单峰型周年变动模式(最高峰位于7月)相比,差异较大.这可能是2001-2002年厄尔尼诺现象导致粤东地区气候异常、干旱少雨,以及调查海区无机磷剧减45%所致.中肋骨条藻(Skeletonema costatum)为该湾的全年优势种,在群落总细胞数中的百分比年均值从上一年度的58.7%上升至本年度的71.0%,导致Shannon-Wiener多样性指数从上一年度的1.91减少至本年度的1.75.中肋骨条藻的绝对占优已在很大程度上改变了该湾浮游植物的群落结构,并使中肋骨条藻赤潮的发生机率大大增加.陆源排污、大规模增养殖业和水体交换对柘林湾高营养盐低浮游植物密度及浮游植物群落的时空分布具最重要的影响.     

准噶尔盆地东部棕尾鵟繁殖生态学研究

2005年4月至6月,在新疆准噶尔盆地东部地区对棕尾鵟的繁殖生物学进行了研究.通过对棕尾鵟(Buteo rufinus)10个巢的观察,发现巢体大多在山体阴面.对棕尾鵟的26枚卵进行测量,长径是56.24 mm±2.58 mm,短径是43.10 mm±0.93 mm.通过对亲鸟孵卵及育雏情况的观察,此地区棕尾鵟的窝卵数2～4枚,孵化率是0.433,幼鸟成活率为0.692,棕尾鵟繁殖力为0.499.在研究中发现,巢内的毛皮、布片、塑料袋等铺垫物由于被风吹起盖住卵而导致亲鸟弃巢的现象严重.10只卵由于巢内铺垫物的覆盖而导致孵化失败.     

中国海洋底栖生物学发展回顾与展望*

海洋底栖生物是海洋生态系统中的重要组成部分,在底层生态系统的能量流动和物质循环过程发挥着重要作用。我国的海洋底栖生物学经过数十年的发展,取得的许多研究进展和成果,但学科目前发展仍存在很多不足。总体而言,研究力量相对薄弱和分散,仍为相对弱势的一个学科,需成立专门的底栖生物学组织机构(分会),构建一个学科交流与合作的平台,整合业内的研究力量和资源,促进我国底栖生物学的研究与发展。本文分析了学科的现状和发展趋势,阐述了海洋底栖生物学分会在学科发展中的作用,并就未来发展提出了建议。     

湖相介形虫古生态学在环境变化研究中的应用

湖泊的水文状况和水化学条件 ,特别是盐度、离子组成、温度及深度等不仅对介形虫种属的分类、组合、丰度及分异度 ,而且对介形虫壳体的大小、形态、结构、壳饰及厚度也起着重要的控制作用。湖相介形虫的古生态学 ,可以提供重要的环境变化信息 ,近年来在环境变化研究中得到越来越广泛的应用。为了满足高分辨率环境变化 ,特别是定量研究的要求 ,必须了解介形虫的种属分类知识 ,掌握盐度和离子组成对介形虫种属变化的影响 ;必须了解介形虫种属的生命历史和生态消长的过程 ,积累介形虫种属的生态资料 ;通过定期收集野外介壳和水样分别进行种属鉴定和化学分析 ,了解湖水的盐度和温度对介壳生态特征的影响。     

沙家浜湿地保护、恢复规划与探索

对沙家浜湿地景观进行了分析,并从湿地总体布局、地形与水系、水质净化、湿地景观保护、野生动植物栖息地保护与恢复、科学研究与检测等方面进行了湿地保护与恢复的探索与规划,为湿地公园保护与恢复规划提供思路和借鉴。     

Plant communities of central Tibetan pastures in the Alpine Steppe/Kobresia pygmaea ecotone

Eleven plant communities of the central Tibetan ecotone (31°20′-33°00′N/89°00′-92°10′E) between the Kobresia pygmaea grazing pastures of the eastern highlands and the open short grass steppe with cushion plants (“Alpine Steppe”) of the north-western highlands have been described on the basis of 189 plot-based floristically complete vegetation records. In parallel, remote sensing techniques distinguish four main land-use cover types. Our hypotheses are: (1) The plant communities of the central Tibetan highlands are grazing-adapted and resilient to degradation. (2) In contrast to grazing resilient plant functional types, the turf cover of the K. pygmaea pastures and the Kobresia schoenoides wetlands is degradable through desiccation, periglacial processes, soil-dwelling small mammals and livestock. Five grazing-related plant functional traits are introduced. Grazing tolerance is the prevalent functional type. Species with no specific protection against grazing make up not more than 6% of the total cover. Unpalatable plants cover up to 8%. Only the azonal K. schoenoides swamps - the indispensable winter grazing reserve - have been widely degraded and depleted by 75%, being replaced by Carex sagaensis grazing pastures. It can be foreseen that governmental policy of sedentarisation of nomads will lead to reduced grazing mobility and degradation of winter grazing reserves.     

自然湿地与人工湿地生态占补平衡研究

自然湿地与人工湿地的功能与效益并不完全相同。实现湿地生态占补平衡,必须考虑占补湿地的替代性与同质性。人工湿地与自然湿地的替代性是解决湿地生态占补平衡的关键问题之一。建立自然湿地与人工湿地占补平衡的约束机制,占用自然湿地时,可以新建人工湿地,还可以恢复自然湿地。通过确保自然湿地生态量、生态功能与生态效益的均衡,减少湿地的生态损失。尽可能在同一水文单位或同流域内实现湿地生态占补平衡。资金投入要兼顾现有自然湿地的生态恢复与新建人工湿地。     

Political ecology in North America: Discovering the Third World within?

Political ecologists working in many other parts of the world are now heading north, or simply going global, posing a series of important questions related to theory, methodology, politics, and policy along the way. This special issue, contains papers originally delivered at a conference held at Rutgers University in 2003 that addressed this phenomenon. The papers collected offer case studies that reveal the First World as subject to a host of processes that can be insightfully understood via a political ecology perspective. First, globalized production and consumption regimes have created new linkages that demand synoptic analyses of often far-flung research sites. Second, the painful coincidence of deindustrialization and a radical restructuring of agricultural credit and price support systems have devastated North American and European heartlands, effectively producing “Third World” conditions in many depressed rural areas. Third, migration streams originating in Latin America, Africa and many parts of Asia have brought sizable Third World populations into the spatial heart of capitalism. Fourth, the belated recognition of some indigenous claims to resources, especially in Canada, and fierce opposition to others, have reopened questions of (internal) colonial domination. Finally, we see the burgeoning First World political ecology literature as the culmination of what Louise Fortmann has called “the long intellectual journey home” for many scholars who originally carried out research on/in the Third World. All of these factors have combined to help political ecologists discover suitable analytical terrain in the First World.