长江淡水潮汐湿地植物特性和植物群落演替研究——以镇江北固山湿地为例

镇江北固山湿地属于长江近河口段淡水潮汐湿地,植物群落基本保持原生演替的前期状况。根据对该湿地的实地观测研究,描述了河滨湿地植物的生长特性;结合湿地的水文特征刻画了湿地高等水生植物在时间、空间和景观上的生态过程;综合河滨湿地植物的生长特性及湿地的水文特征探讨了镇江淡水潮汐湿地的演变趋势。对湿地面临的问题进行了讨论,从而为长江淡水潮汐湿地的生态修复和增加生物多样性及湿地保护提供参考。     

The mating system of Hanuman langurs: a problem in optimal foraging

Using data from 23 populations of Indian langurs (Presbytis entellus), we show that the proportion of one-male groups is a function of the males’ ability to defend groups of females, as predicted by the monopolisation model of Emlen and Oring (1977). However, we show that in addition to the number of females in the group and their reproductive synchrony, home range size is also a factor, probably because it affects a male’s willingness to search for other groups. These variables in turn are shown to be functions of environmental parameters (rainfall volume and seasonality, and mean ambient temperature) which probably act via the density of resources and refuges in habitats. Received: 3 March 1994 / Accepted after revision: 24 June 1996     

MODELING EFFECTS OF BRUSH MANAGEMENT ON THE RANGELAND WATER BUDGET: EDWARDS PLATEAU,TEXAS1

ABSTRACT: The Soil and Water Assessment Tool (SWAT) was used to evaluate the influence of woody plants on water budgets of semi‐arid rangelands in karst terrain. The model was configured for the hydrologic evaluation of the North Fork of the Upper Guadalupe River watershed and was calibrated and verified using measured flow data. Nash and Sutcliffe fit efficiencies for daily and monthly verification periods were 0.09 and 0.50, respectively. Streamflow, baseflow, and evapotranspiration (ET) rates were comparable to published field data. Simulated deep recharge was considerably higher than the published values for the Edwards Plateau. The model was then used to simulate conditions with existing brush cover and four different brush removal scenarios. Scenarios were created to represent existing brush and the removal of brush from only locations that were either covered by heavy brush, were on a moderate slope, or were in shallow soils. Resulting data was compared to previous studies of both field experiments and model simulations. Maximum brush removal resulted in a reduction in ET equal to 31.94 mm/yr depth over the entire basin, or 46.62 mm/yr depth over the treated area. Removal of heavy brush cover resulted in the greatest changes in evapotranspiration, surface runoff, base‐flow, and deep recharge. Slope was found to have the greatest effect on lateral subsurface flow.     

盐城自然保护区人工湿地对水鸟分布的影响

通过定位观察，进行了人工湿地内鸟类的种类鉴别和数量统计。结果表明，２２０ｈｍ~２人工湿地先后招引了包括丹顶鹤在内的５５种水鸟前来栖息。并通过与人工湿地建立以前调查结果的分析比较，阐述了建立人工湿地对整个保护区生态系统功能的调节和补充作用。     

Wood Density as a Conservation Tool: Quantification of Disturbance and Identification of Conservation‐Priority Areas in Tropical Forests

Abstract: Inventories of tree species are often conducted to guide conservation efforts in tropical forests. Such surveys are time consuming, demanding of expertise, and expensive to perform and interpret. Approaches to make survey efforts simpler or more effective would be valuable. In particular, it would be good to be able to easily identify areas of old‐growth forest. The average density of the wood of a tree species is closely linked to its successional status. We used tree inventory data from eastern Borneo to determine whether wood density can be used to quantify forest disturbance and conservation importance. The average density of wood in a plot was significantly and negatively related to disturbance levels, with plots with higher wood densities occurring almost exclusively in old‐growth forests. Average wood density was unimodally related to the diversity of tree species, indicating that the average wood density in a plot might be a better indicator of old‐growth forest than species diversity. In addition, Borneo endemics had significantly heavier wood than species that are common throughout the Malesian region, and they were more common in plots with higher average wood density. We concluded that wood density at the plot level could be a powerful tool for identifying areas of conservation priority in the tropical rain forests of Southeast Asia.     

独头巷道受限贴附射流有效射程的 理论研究与数值计算

为了探讨独头巷道受限贴附射流通风有效射程,利用巷道断面面积与风筒出流射流直径,定义了独头巷道射流的受限程度,采用理论分 析与数值计算方法,推导了受限射流无因次距离与沿程断面位置、断面流量和断面平均流速之间的关系式,建立了独头巷道受限贴附射流流动 特性模型。利用该模型,开展了8个不同工况下受限贴附射流的数值计算。结果表明,在受限的情况下,射流区无因次最大截面积出现在无因次 距离为0.200 0处,而无因次最大截面流量位于无因次距离为0.187 5处。理论推导和计算结果表明,所得模型和计算方法能更为准确预测受限 贴附射流的有效射程。     

潮汐河口水库型饮用水水源地保护区划分技术方法

长江口作为上海重要水源地,至今还没有依法划定水源保护区。目前国内的饮用水水源地保护区划分技术方法在潮汐河口水域应用时存在科学性差、适用性不强等问题。对国内外饮用水水源地保护区的划分方法进行了调研;研究了河口潮汐往复流特征、水污染排放、水环境特点,明确了河口水源库水质净化和防范突发污染事故风险的要求,提出了充分利用水库库区自净能力的划分原则和应用污染物最大流动距离法划分潮汐河口水库型水源地二级水源保护范围的技术方法。以氨氮作为特征因子分析水库的自净能力,认为库区作为一级保护区可以承担二级保护区的水质净化功能。以99%保证率的涨落潮流速并考虑季风的影响计算得到最大流动距离,并以此确定了青草沙水库的二级保护区范围上下游和横向边界范围。研究表明该方法概念清晰,简单实用,可靠性强。     

Specific features of annual cycles in long-distance migrant birds living at the range boundary: the example of the wood warbler, <Emphasis Type="Italic">Phylloscopus sibilatrix</Emphasis>, in the taiga zone of northwestern Russia

Annual cycle phenomena taking place in the nesting part of the range, such as dates of migration and breeding and molting pattern, have been studied in the wood warbler in northwestern Russia, at the boundary of its nesting range. The results provide evidence that the annual cycle of long-distance migrant birds living at the boundary of their nesting range has certain specific features.     

工业LNG储罐泄漏扩散数值模拟

针对工业LNG储罐泄漏问题,基于Fluent软件结合UDF修正风速模型,研究不同工况下泄漏发展情况,并对泄露口下风向沿直线距离上的泄漏气体浓度进行分析,得出准确气体扩散浓度范围.研究结果表明,泄漏孔口越接近地面,横向扩散距离越大.相同风速下,泄漏路径上气体浓度具有相似的变化趋势,风速越高泄漏气体沿扩散路径的稀释作用越强...