石羊河流域下游民勤县生态需水量研究

在大量调查资料及试验的基础上,结合对近几年来的科研成果及相关资料分析,从系统的角度,研究了石羊河流域生态需水量,并提出了在一定水资源条件下的受损生态系统恢复建议。     

A management driven investigation of landscape patterns of northern spotted owl nesting territories in the high Cascades of Oregon

Investigations using available data sought to guide short-term management decisions regarding the needs of northern spotted owl in the high Cascade Mountains of Oregon. Landscape attributes and pattern indices were measured and tested for identification of areas likely to contain northern spotted owl nests. Predictive models indicating planning standards were developed. Most landscape ecological indices were not useful. Results indicate the owl favors landscapes dominated by patches that meet definitions of late seral forest nesting habitat. The owl optimally nests in such patches at least 570 hectares in size. Landscapes with some edges, particularly around nesting habitat patches evidently do not adversely affect the owl, perhaps because they provide prey. Landscapes with extensive edges, particularly between openings and forests not suitable for nesting, are not as likely to be selected. The results are largely consistent with the owl's recovery plans, provide guidance for management, and require refinement through additional research, particularly to better determine home range sizes.     

Modeling the effects of forest harvesting on landscape structure and the spatial distribution of cowbird brood parasitism

Timber harvesting affects both composition and structure of the landscape and has important consequences for organisms using forest habitats. A timber harvest allocation model was constructed that allows the input of specific rules to allocate forest stands for clearcutting to generate landscape patterns reflecting the look and feel of managed landscapes. Various harvest strategies were simulated on four 237 km² study areas in Indiana, USA. For each study area, the model was applied to simulate 80 years of management activity. The resulting landscape spatial patterns were quantified using a suite of landscape pattern metrics and plotted as a function of mean harvest size and total area of forest harvested per decade to produce response surfaces. When the mean clearcut size was 1 ha, the area of forest interior remaining on the landscape was dramatically reduced and the amount of forest edge on the landscape increased dramatically. The potential consequences of the patterns produced by the model were assessed for a generalized neotropical migrant forest bird using a GIS model that generates maps showing the spatial distribution of the relative vulnerability of forest birds to brood parasitism by brown-headed cowbirds. The model incorporates the location and relative quality of cowbird feeding sites, and the relation between parasitism rates and distance of forest from edge. The response surface relating mean harvest size and total area harvested to the mean value of vulnerability to cowbird brood parasitism had a shape similar to the response surfaces showing forest edge. The results of our study suggest that it is more difficult to maintain large contiguous blocks of undisturbed forest interior when harvests are small and dispersed, especially when producing high timber volumes is a management goal. The application of the cowbird model to landscapes managed under different strategies could help managers in deciding where harvest activity will produce the least negative impact on breeding forest birds.     

Influences of upland and riparian land use patterns on stream biotic integrity

We explored land use, fish assemblage structure, and stream habitat associations in 20 catchments in Opequon Creek watershed, West Virginia. The purpose was to determine the relative importance of urban and agriculture land use on stream biotic integrity, and to evaluate the spatial scale (i.e., whole-catchment vs riparian buffer) at which land use effects were most pronounced. We found that index of biological integrity (IBI) scores were strongly associated with extent of urban land use in individual catchments. Sites that received ratings of poor or very poor based on IBI scores had > 7% of urban land use in their respective catchments. Habitat correlations suggested that urban land use disrupted flow regime, reduced water quality, and altered stream channels. In contrast, we found no meaningful relationship between agricultural land use and IBI at either whole-catchment or riparian scales despite strong correlations between percent agriculture and several important stream habitat measures, including nitrate concentrations, proportion of fine sediments in riffles, and the abundance of fish cover. We also found that variation in gradient (channel slope) influenced responses of fish assemblages to land use. Urban land use was more disruptive to biological integrity in catchments with steeper channel slopes. Based on comparisons of our results in the topographically diverse Opequon Creek watershed with results from watersheds in flatter terrains, we hypothesize that the potential for riparian forests to mitigate effects of deleterious land uses in upland portions of the watershed is inversely related to gradient.This revised version was published online in May 2005 with corrections to the Cover Date.     

Dams in the Amazon: The importance of maintaining free-flowing tributaries for fish reproduction

1. Free-flowing tributaries are important for the maintenance of fish diversity in dammed systems. In relation to the reproduction of fish species, the role of a free-flowing tributary was evaluated and compared with that of a dammed tributary downstream of large dams in the Madeira River, one of the main tributaries of the Amazon River.
2. Two hypotheses were tested: (i) the densities of the ichthyoplankton differ between the dammed and the free-flowing tributaries; and (ii) the free-flowing tributary contributes a greater diversity of fish larvae species to the assemblage structure of the main stem than the dammed tributary.
3. Fish eggs and larvae were sampled at five sites: one in each tributary (Jamari – dammed – and Machado – free-flowing) and three in the main stem (Madeira River), upstream and downstream from the mouth of each tributary.
4. Fitted Bayesian models showed that the densities both of eggs and larvae were more than twice as high in the free-flowing tributary than in the dammed tributary. The results also indicated that the free-flowing tributary makes a major contribution to the fish assemblage structure of the Madeira River, whereas the dammed tributary does not have a significant influence on the main stem assemblage structure.
5. The results demonstrate the importance of conservation and maintenance not only of the Machado River but also of other free-flowing tributaries in dammed basins, especially those basins with high biodiversity, such as the Amazon. Moreover, this study helps inform the decision-making process regarding the location of new dams, which is critical in fish diversity conservation.

     

Occurrence and mobility of the insecticide permethrin in rivers in the Southern Humber catchment,UK

The synthetic pyrethroid insecticides cis‐ and trans‐permethrin are widely used, particularly in sheep‐dips and for mothproofing within the textile industry. This study aims to establish the concentrations and mobility of permethrin within rivers in the Humber catchment, which contain some of the highest densities of wool‐scouring activity in the world. Our approach was to utilise three different surveys: (a) weekly and storm‐responsive sampling of ‘whole waters’ in the rivers Aire, Ouse, Don, Trent and Calder; (b) intensive sampling of ‘whole waters’ and suspended sediments in the rivers Aire (0.5 h) and Calder (1 h); (c) a bed‐sediment survey of the River Calder. Sediments were extracted by supercritical fluid extraction and all samples were analysed by gas chromatography with mass spectrometry. Results demonstrated the presence of permethrin in ‘whole waters’ and sediments, particularly in the rivers Aire and Calder, and at concentrations in the bed‐sediment likely to cause ecotoxicological effects to benthic macro‐invertebrates. Mass‐balance calculations indicated some loss of permethrin from the water column during transport, with the greatest losses at low river‐discharge. Isomer ratios (trans:cis) give retention times of permethrin in different components of the system as ‘whole water’ < suspended sediments < bed‐sediments, with estimates of 4–26 days for suspended sediments and a maximum of 103–125 days for surface bed‐sediments. © 2000 Society of Chemical Industry     

Close chromosomal congruence in two species of ground squirrel: Xerus inauris and X. princeps (Rodentia: Sciuridae)

Chromosomes from cultured fibroblasts of two southern African ground squirrel species, Xerus inauris (2n = 38) and X. princeps (2n = 38), were compared using G-banding, C-banding and silver nitrate staining for the detection of NORs (nucleolar organizer regions). The karyoptypes of the two species, whose taxonomic status is the subject of some uncertainty, are largely identical except for a subtle heterochromatic difference which affects a single autosomal chromosome pair in X. inauris. The species specificity of this marker in their zone of contact indicates an absence of gene flow between these taxa and gives credence to the recognition of X. inauris and X. princeps as two biologically distinct species.     

基于人工鱼群算法南宁市内河水质综合评价的投影寻踪回归分析

针对目前我国城市内河普遍遭到污染的问题,在分析影响内河水质因素的基础上,选取BOD5（五日生化需氧量）、CODcr（化学需氧量）、石油类、挥发酚、NH3-N（氨氮）、总磷等6个主要因素作为评价因子,建立了城市内河水质评价的投影寻踪分析模型,采用人工鱼群算法对评价模型进行优化,并将该模型应用于南宁市10条内河水质的评价与排序。研究表明,用投影寻踪回归分析法进行水质评价,避免了传统评价方法由于主观原因造成的误差,评价结果合理可信、方法简单,为我国城市内河水质的评价提供了新途径。     

水库群洪灾风险的综合评价及加固决策研究

以长台溪流域10座小Ⅱ型以上水库的安全认定和社会经济调查为基础,通过单坝失事风险分析、失事后果评估计算,进行单坝的洪灾风险评价;进而从流域整体的角度,考虑库间影响,洪灾风险的传递、积聚效应,量化分析全流域各水库的洪灾综合风险。在此基础上,进行系统内各座水坝洪灾综合风险的大小排序,转化为除险加固的优先次序,为后续加固决策提供参考。     

河流泥沙的环境效应分析

分析了泥沙环境效应的研究状况,讨论了吸附在泥沙上的污染物迁移转化的模式与计算模型,简要说明了利用模型推求污染物质量浓度与吸附污染物量的方法。研究表明,悬移质对重金属的吸附大都可以用Freundlich型或Langmuir型吸附等温式进行较好的拟合;基于泥沙粒径对金属吸附的独立性,可采用等效粒径的等温式进行试验拟合,建立吸附预测模型。通过已有Freundlich模型对贾鲁河水体中总磷的计算,发现随着二站间含沙量的增大,二站总磷含量减小,泥沙吸附磷在总磷中所占的比例增大。