冻融循环条件下生境基材中三种功能微生物数量变化规律研究

为揭示高寒地区典型生境基材中功能微生物数量变化的规律,以黄棕壤土为试验土样,在两种初始含水率条件下,分别制备客土、植被混凝土以及加菌植被混凝土三种不同类型的生境基材进行冻融循环模拟试验,探讨生境基材类型、初始含水率和冻融循环次数对基材中功能微生物数量的影响。试验结果显示：三种基材中功能微生物数量均受冻融循环影响显著,且随冻融循环次数增加总体呈"下降~上升~下降"趋势;冻融循环过程中,三种基材中功能微生物总量存在显著性差异,排序为：加菌植被混凝土 > 植被混凝土 > 客土,且固氮、解钾微生物数量显著低于解磷微生物;含水率为22%的基材中功能微生物总量普遍高于含水率为18%的基材。研究结果表明,加菌植被混凝土的肥力、抗冻性相比客土和植被混凝土有一定程度提升,但仍需对现有功能菌剂配方加以改进,以适应高寒地区冻融环境。     

基于地理探测器的大熊猫生境适宜度评价模型及验证

动物生境适宜度评价对于野生动物生境保护十分重要。基于物种活动点来建模的生态位模型是目前应用最广泛的动物生境评价方法,但该方法不能直接表达生境适宜度与环境因子间具有生态学意义的数量关系。本文以雅安地区为例,提出一种新的大熊猫（Ailuropoda melanoleuca）生境适宜度评价方法,选取海拔、坡度、坡向、地形指数、距水源距离、植被类型、主食竹及距公路距离8个环境因子,引入地理探测器,在分别基于MAXENT模型和层次分析法（The Analytic Hierarchy Process,AHP）所构建生境适宜度模型的基础上,通过4个地理探测器（风险探测器、因子探测器、生态探测器和交互作用探测器）探寻大熊猫生境与各环境因子间的关系以及环境因子对大熊猫生境的影响机理,并将其预测结果与单一MAXENT模型和AHP法进行对比。结果表明：（1）AHP、AHP-Geogdetector、MAXENT和MAXENT-Geogdetector模型总体评价精度分别为85.6%、86.5%、91.3%和94.2%,kappa系数分别为0.699、0.718、0.821和0.882,AUC值分别为0.902、0.928、0.949和0.966,模型所预测的适宜和较适宜区与实际分布区重叠比分别为63.66%、61.30%、76.70%和90.10%,说明AHP-Geogdetector和MAXENT-Geogdetector模型精度均比相应的单一模型有所提高,且MAXENT-Geogdetector模型精度最高;（2）基于地理探测器的大熊猫生境适宜度评价模型能以“生境适宜度和环境因子间具有生态学意义的数量关系”的形式直接体现环境因子对动物生境利用的生态学作用,具有较好的生态学可解释性。因此,用地理探测器进行大熊猫生境适宜度评价具有较好的可行性。     

Quantifying suitable dynamic water levels in marsh wetlands based on hydrodynamic modelling

The water level of marsh wetlands is a dominant force controlling the wetland ecosystem function, especially for aquatic habitat. For different species, water level requirements vary in time and space, and therefore ensuring suitable water levels in different periods is crucial for the maintenance of biodiversity in marsh wetlands. Based on hydrodynamic modelling and habitat suitability assessment, we determined suitable dynamic water levels considering aquatic habitat service at different periods in marsh wetlands. The two-dimensional hydrodynamic model was used to simulate the temporal and spatial variation of water level. The habitat suitability for target species at various water levels was evaluated to obtain the fitting curves between Weighted Usable Area (WUA) and water levels. And then suitable water levels throughout the year were proposed according to the fitting curves. Using the Zhalong Wetland (located in northeastern China) as a case study, we confirmed that the proposed MIKE 21 model can successfully be used to simulate the water level process in the wetland. Suitable water levels were identified as being from 143.9–144.2 m for April to May, 144.1–144.3 m for June to September, and 144.3–144.4 m for October to November (before the freezing season). Furthermore, proposed water diversion schemes have been identified which can effectively sustain the proposed dynamic water levels. This study is expected to provide appropriate guidance for the determination of environmental flows and water management strategies in marsh wetlands.     

A new approach to rapid,desktop-level,environmental flow assessments for rivers in South Africa

Abstract

An approach is presented for desktop-level environmental flow requirement (EFR) determination that is aligned with the Habitat Flow–Stressor Response (HFSR) method which evolved in South Africa over recent years. The HFSR method integrates hydrological, hydraulic and ecological habitat data, involves ecological and hydraulic specialists and is data-intensive and time-consuming. The revised desktop method integrates hydrological information with estimates of channel hydraulic cross-sectional characteristics to generate habitat-type frequencies under changing flow conditions. This information is used with the expected natural habitat requirements to determine acceptable habitat availability under different levels of ecological protection, which is then used with the hydraulic data to define flow regime characteristics that meet the ecological objectives. The paper describes the model components, discusses the assumptions, data requirements and limitations and presents some example results. The revised desktop approach uses approaches that are aligned with the more complex methods and generates results that are similar.

Editor D. Koutsoyiannis; Guest editor M. Acreman

Citation Hughes, D.A., Desai, A.Y., Birkhead, A.L., and Louw, D., 2014. A new approach to rapid, desktop-level, environmental flow assessments for rivers in South Africa. Hydrological Sciences Journal, 59 (3–4), 673–687.     

Experimental field assessment of suspended sediment pathways for characterizing hydraulic habitat

The distribution of particulate matter within river channels, including sediments, nutrients and pollutants, is fundamental to the survival of aquatic organisms. However, the interactions between flow and sediment transport at the patch scale of river systems represents an under‐researched component of physical habitat studies, particularly those concerning the characterization of ‘physical biotopes’ (riffles, runs, pools, glides). This paper describes a field methodology for exploring the transfer of particulate matter at small scales within river channels, which may be used to aid hydraulic habitat characterization. The field protocol combines field measurement of high frequency flow properties, to characterize hydraulic habitat units, and deployment of spatial arrays of turbidity probes, to detect the passage of artificially‐induced sediment plumes through different biotope units. Sediment plumes recorded by the probes are analysed quantitatively in the manner of the flood hydrograph, and qualitative inferences are made on the dominant mixing processes operating within different parts of the channel. Relationships between the nature of spatio‐temporal hydraulic variations within glide, riffle and pool biotopes, and the character and mixing behaviour of sediment plumes within these habitat units are identified. Results from these preliminary experiments suggest that investigating and characterizing the transfer and storage of sediments, nutrients and pollutants within and between different biotopes is a viable avenue for further research, with potential to contribute to improved physical habitat characterization for river management and habitat restoration. The experiments are also an illustration of the value of neglected synergies between process geomorphology, ecology and river hydraulics. Copyright © 2010 John Wiley & Sons, Ltd.     

安徽升金湖国家级自然保护区水鸟生境适宜性变化

水鸟是湿地生态系统健康的指示生物,人类活动对其影响日益严重.研究自然保护区内的水鸟生境适宜性变化可以为湿地恢复提供帮助.通过层次分析法确定水鸟生境影响因子的权重,建立生境适宜性指数模型,根据TM遥感影像图和相关数据计算出安徽省升金湖国家级自然保护区1986-2011年5个年份的水鸟生境适宜指数,并结合GIS空间分析生成的水鸟生境适宜性分级图,分析升金湖建立保护区后水鸟生境适宜性变化.结果表明:升金湖地区在1986年建保护区后的几年间水鸟生境适宜性相对平稳,但是仍然有较为明显的下降;1990s后期,该地区水鸟生境适宜性开始显著恶化,一直持续到2000年之后才有小幅度的回升.水鸟生境适宜性最好的区域由片状分散逐渐转变成小范围聚集,适宜区域也在由实验区和缓冲区向核心区迁移的过程中显著缩减.本文还讨论了在研究中存在的不足,并提出一些恢复水鸟生境的建议.     

Optimizing Remote Sensing and GIS Tools for Mapping and Managing the Distribution of an Invasive Mangrove (Rhizophora mangle) on South Molokai,Hawaii

In 1902, the Florida red mangrove, Rhizophora mangle L., was introduced to the island of Molokai, Hawaii, and has since colonized nearly 25% of the south coast shoreline. By classifying three kinds of remote sensing imagery, we compared abilities to detect invasive mangrove distributions and to discriminate mangroves from surrounding terrestrial vegetation. Using three analytical techniques, we compared mangrove mapping accuracy for various sensor-technique combinations. ANOVA of accuracy assessments demonstrated significant differences among techniques, but no significant differences among the three sensors. We summarize advantages and disadvantages of each sensor and technique for mapping mangrove distributions in tropical coastal environments.     

Conservation of wetlands especially as waterfowl habitat in northeast China

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长沙都市区生境质量对城市扩张的时空响应

生境质量是评价生态环境的重要指标,掌握其对城市扩张的时空响应规律,有助于提升都市区城乡规划质量和生态管控的合理性。本文在运用InVEST模型对长沙都市区1995-2015年生境质量时空演化的基本特征进行分析的基础上,利用缓冲区由内向外逐层剖析,探讨长沙都市区近20年来城市扩张格局及其对生境质量的影响。结果表明：①长沙都市区建设用地面积从170.26 km²增至487.19 km²;三环线以内建设用地快速扩张,从三环线起向外扩张逐渐放缓;②生境质量中等及以上的区域占比从1995年的43.49%下降到2015年的27.22%,生境质量平均值则相应地从0.46下降到0.31,且退化最明显的区域从核心外围区(5-10号缓冲区)外移到三环线附近(10-15号缓冲区);③各圈层建设用地扩张强度与生境质量变化之间存在显著的空间负相关性,生境质量变化对城市扩张响应最强烈的区域始终位于核心外围区;④建设用地空间布局零散和几何形态不规则程度的增加加剧了生境质量的退化,并在三环线附近区域(10-15号缓冲区)表现最为明显,应成为未来长沙都市区城乡规划和生态管控的重点区域。