澜沧江梯级开发下鱼类支流生境替代效果

作为干流高坝水电开发导致鱼类生境丧失的一种补偿措施，支流替代生境近年来被广泛应用于受工程影响河段的土著鱼类保护，但替代支流发挥怎样的保护效果及干流对其的影响仍不清楚。以实施了澜沧江梯级生境替代的支流基独河与罗梭江为研究对象，并选择了邻近的对照支流，通过对鱼类调查数据的分析对比，揭示了各支流鱼类种类组成与群落结构的差异特征，初步阐明了梯级开发下鱼类支流生境替代效果以及干流工程建设对其的影响。结果表明：澜沧江支流替代生境对干流鱼类具有明显的保护作用，支流生境修复后鱼类物种丰富度明显提高，罗梭江土著鱼类、特有鱼类物种数分别增加了12种、7种，基独河则是7种、2种，替代生境能为澜沧江土著鱼类、部分濒危特有鱼类和洄游鱼类提供完成生活史的关键栖息地。干流对支流生境替代保护有着重要影响，罗梭江、基独河与邻近干流鱼类群落的Bray-Curtis相似性分别为21.76%、10.73%,支流河口段保持“河相”是支流生境替代保护效果可持续的关键。综合考虑生境替代保护的效益与投入，建议今后开展此类保护措施时优先选择库尾河相区的支流。     

Freshwater marsh vegetation response to flooding patterns in the lower delta of the Parana river

Freshwater marshes are the only significant natural ecosystems remaining in the Buenos Aires province section of the Lower Delta of the Parana River (Argentina), occupying 80% of the total island area. The Lower Delta hydrology is dominated mainly by the Parana river and the De La Plata estuary; different temporal superpositions of floods and landscape configurations of the islands result in four distinct flooding patterns. We studied the response of freshwater marsh vegetation to the flooding patterns using principal component analysis and cluster analysis. The study area was gridded and 13 cells were selected representing the different flooding patterns. We found significant environmental heterogeneity in the region and a consequent response in the vegetation, expressed through successive species replacements, and variation in species richness and the number and type of dominant species. The environmental heterogeneity of the region is caused by hydrological variations, geomorphological changes in the islands from upstream to downstream areas of the delta, and patterns of human activity.     

Establishment and growth of hawthorn in floodplains in the Netherlands

Dendrochronology was used to assess the influence of soil conditions, elevation and related inundation, climate fluctuations and vegetation cover on the establishment and growth of hawthorn in non-grazed river floodplains. Presence of forest influences the discharge capacity of the floodplain, therefore forest development needs to be considered in management plans. Although ring detection in hawthorn is difficult, clear dynamics in establishment and growth of this shrub species were found. Establishment was mainly influenced by inundation (length and height). The effect of inundation on establishment is location dependent; positive due to transport and deposition of seeds in higher areas, and negative due to drowning of young plants in lower locations. Extreme climatic events were found to influence establishment including a drought in 2003 and relatively low and high precipitation in 2004–2006 and 2007 respectively. These events combined with almost no inundation caused some anomalies in the time series for hawthorn establishment. Once above a certain height, hawthorn is able to withstand various abiotic disturbances occurring in these dynamic river floodplains. Excavated areas are enhancing forest development following hawthorn establishment and therefore these areas should be limited in size (e.g. by deeper and narrower excavations and thus a steeper transition towards the grasslands).     

基于InVEST模型的疏勒河流域碳储量时空变化研究

研究区域土地利用方式与生态系统服务碳储量的关系，对于区域生态系统保护及经济社会可持续发展具有重要意义。利用InVEST模型碳储量模块和CA-Markov模型，探究并预测疏勒河流域1990-2015及2015-2040年流域生态系统碳储量时空变化特征及其与土地利用方式之间的关系。结果表明：疏勒河流域1990、1995、2000、2005、2010、2015年碳储量分别为7.994×10⁸、7.996×10⁸、7.998×10⁸、8.038×10⁸、8.064×10⁸、8.071×10⁸t，呈逐年增加趋势，累计增加7.7×10⁶t。土地利用类型变化是导致生态系统碳储量变化的主要因素，未利用地向耕地和草地转化有利于碳储量增加，而草地向耕地和未利用地的转化则导致碳储量减少。疏勒河流域碳储量存在显著的空间格局，碳储量较高区域呈现"北部点状-中部带状-南部点状片状"特征，这种分布格局与流域土地利用类型紧密联系。预测表明至2040年疏勒河流域碳储量为9.128×10⁸t，较2015年增加13.1%，主要原因是草地、耕地和林地面积较大幅度增长，提高了流域内的碳储量。     

Stream hierarchy defines riverscape genetics of a North American desert fish

Global climate change is apparent within the Arctic and the south‐western deserts of North America, with record drought in the latter reflected within 640 000 km² of the Colorado River Basin. To discern the manner by which natural and anthropogenic drivers have compressed Basin‐wide fish biodiversity, and to establish a baseline for future climate effects, the Stream Hierarchy Model (SHM) was employed to juxtapose fluvial topography against molecular diversities of 1092 Bluehead Sucker (Catostomus discobolus). MtDNA revealed three geomorphically defined evolutionarily significant units (ESUs): Bonneville Basin, upper Little Colorado River and the remaining Colorado River Basin. Microsatellite analyses (16 loci) reinforced distinctiveness of the Bonneville Basin and upper Little Colorado River, but subdivided the Colorado River Basin into seven management units (MUs). One represents a cline of three admixed gene pools comprising the mainstem and its lower‐gradient tributaries. Six others are not only distinct genetically but also demographically (i.e. migrants/generation <9.7%). Two of these (i.e. Grand Canyon and Canyon de Chelly) are defined by geomorphology, two others (i.e. Fremont‐Muddy and San Raphael rivers) are isolated by sharp declivities as they drop precipitously from the west slope into the mainstem Colorado/Green rivers, another represents an isolated impoundment (i.e. Ringdahl Reservoir), while the last corresponds to a recognized subspecies (i.e. Zuni River, NM). Historical legacies of endemic fishes (ESUs) and their evolutionary potential (MUs) are clearly represented in our data, yet their arbiter will be the unrelenting natural and anthropogenic water depletions that will precipitate yet another conservation conflict within this unique but arid region.     

The method matters: A guide for indicator aggregation in ecological assessments

Ecological assessment requires the integration of many physical, chemical, and/or biological quality elements. The choice of the aggregation method of such partial assessments into an overall assessment can considerably affect the assessment outcome – an issue that has been controversially discussed within the scientific community for the last decade. Current practice often considers only two different aggregation methods, the weighted arithmetic mean (additive aggregation) and the one-out, all-out method (minimum aggregation). However, both have important drawbacks. Additive aggregation compensates a bad status of one quality element by a number of elements featuring good status. Minimum aggregation can lead to overly pessimistic assessment results, since only the quality element in the worst status is considered. Here, we introduce a toolbox containing current and new aggregation methods, demonstrate and discuss their properties with simple, didactical examples, and suggest in which situations best to use them. Then, we illustrate the consequences of selected aggregation schemes for ecological river assessment with the case study of the Swiss Modular Concept of stream assessment (SMC), which we apply to ten river reaches in the Mönchaltdorfer Aa catchment in Switzerland. To be able to do so, we used multi-criteria decision analysis, i.e., multi-attribute value theory, to arrange the SMC quality elements into an objectives hierarchy, and to translate their individual assessments into value functions. Our case study revealed that choosing the most appropriate aggregation method particularly matters, if objectives with significantly different qualities are aggregated. We argue that redundant objectives (i.e., quality elements), often found at the lower levels of the objectives hierarchy, should best be aggregated additively allowing for compensation to increase the statistical significance of the results. Further, we suggest that complementary sub-objectives that often occur at higher levels may be optimally aggregated with a mixture of additive and minimum aggregation. Such a mixed method will allow some compensation, but nevertheless penalize for very bad states. Since here we compare commonly used aggregation methods with some which we believe have never been discussed in an assessment context before, our study concurrently informs ecological assessment in theory and in practice.     

Evidence of a genetically distinct population of Vrljika softmouth trout Salmo obtusirostris Heckel evolved by vicariance

Mitochondrial DNA haplotypes (control region, partial cytochrome b and ATPase6 genes) indicate a sister relationship between Vrljika and Neretva softmouth (Adriatic) trout Salmo obtusirostris . This relationship was supported by a tree of individuals based on microsatellite results [allele sharing distances ( D _AS)], which revealed three distinctive clusters, corresponding to Jadro softmouth, Neretva brown trout Salmo trutta and Neretva softmouth trout. Within the latter taxon, Vrljika trout are clearly separated from other trout. The genetic results contradict the synonymy of Jadro with Vrljika softmouth trout, as recently proposed in the Red Book of Freshwater Fish in Croatia. Vrljika softmouth trout appear to have originated from a vicariance that split a common ancestor into large (Neretva) and small (Vrljika) fragmented populations 135 000–270 000 years ago. Vrljika softmouth trout can be distinguished by an array of derived phenotypic and molecular character states. For conservation, this population should be recognized formally at the same taxonomic level as the other geographically separated populations of softmouth trout.     

Ecological resources for conservation and development in Wadi Allaqi,Egypt*

PULFORD, I. D., MURPHY, K. J., DICKINSON, G., BRIGGS, J. A. & SPRINGUEL, I., 1992. Ecological resources for conservation and development in Wadi Allaqi, Egypt. The creation of Lake Nasser behind the Aswan High Dam on the River Nile has brought about significant environmental changes in Upper Egypt. A multidisciplinary project was started in 1987 to assess the environmental changes associated with periodic inundation in desert ecosystems. The data presented here provide a baseline for studies aimed at assessing the potential for, and ecological impacts of, sustainable development in the target area, and may act as a blueprint for wider-scale development. Soil, water, vegetation, animal and human resources are being monitored. There has been a major increase in plant communities dominated by riverain species, at the expense of the original desert wadi vegetation. The water has attracted human settlement, with some 200–250 people now living in the wadi. The inherent high fertility of the soil has allowed them to grow a range of crops in small plots, using a system of shifting cultivation dictated by the lake water level. While this degree of development may be sustainable, larger-scale development of the fragile wadi ecosystem demands a full assessment of appropriate management techniques.