Environmental and spatial processes: what controls the functional structure of fish assemblages in tropical rivers and headwater streams?

In this study, we investigated functional structure patterns of tropical headwater and river fish assemblages. We hypothesised that environmental conditions are primarily structuring headwater streams leading to functionally clustered assemblages, whereas processes that favour functional overdispersion would guide river assemblages. For 27 headwater streams and 22 rivers, we used eight functional traits for calculating two functional indexes: mean pairwise distance (MPD) and net relatedness index (NRI). We performed linear regressions between indexes and species richness, a multiple regression between NRI and eight environmental variables and a variation partitioning to disentangle the role of environment and space on NRI. Our findings indicate that fish assemblages of headwaters are structured by environmental conditions as most assemblages in this habitat displayed a tendency to clustering and MPD/NRI were not correlated with species diversity, whereas the opposite pattern was observed for river habitat. Four environmental variables (channel depth, water velocity, dissolved oxygen and turbidity) explain 56% of functional structure variation. These variables seem to function as selective filters in headwaters, whereas channel depth may be determinant for functional overdispersion of river fish assemblages. Components associated with space are also influencing the functional structure. Limitations of species dispersal through space (between both habitat types) appear as a possible cause to this. In this sense, both environmental conditions and processes linked with space are capable of influencing the functional structure of tropical headwater streams and river fish assemblages.     

黄河源流域单元概念及其提取方法研究

针对黄河源高寒草地生态系统保护的流域属性与差异性，本研究提出了一种准确便捷的流域单元识别方法。以国产高分辨率遥感影像所提取水系矢量数据作为标准参照系，基于数字高程数据（Digital elevation model，DEM）汇流累积计算量阈值设置为30 000时所获取的水系信息与黄河源实际水系状况较为相近。通过合并集水区获取黄河源流域单元878个，其中干流单元1个，一级支流单元219个，二级支流单元420个，三级支流单元194个，四级支流单元21个，断流河流单元23个。受地形地貌影响黄河源流域单元中河流长度与流域面积差距较大。本研究完善了黄河源水系及流域单元特征信息，为黄河源生态治理工作提供参考。     

Bed disturbance below dams: observations from two Mediterranean rivers

River‐bed disturbance and associated sedimentary processes such as particle mobility are central elements to assess river ecosystem functioning. Dams change river dynamics affecting the magnitude and frequency of biophysical elements that depend on them. This paper examines the effects of two dams different in size, management, and location, on the flow regime, flood competence, and bed disturbance in two contrasting Mediterranean rivers, the Ésera and the Siurana. For this purpose, two reaches on each river were monitored upstream and downstream from reservoirs. Several monitoring and modeling techniques were used to characterize flow competence, particle entrainment, and the volumes of sediments eroded and deposited after floods. The flow regime of the Ésera has been modified from nivo‐pluvial regime, typical of humid mountainous environments, to that observed in dry semiarid regions, in which high magnitude but low frequency floods are the dominant processes. Conversely, the flow regime of the Siurana has changed from a typical Mediterranean stream to a regime observed in more temperate environments, with more permanent and stable flows. Both rivers show notably physical changes, with channels clearly less dynamic below the dams. The lack of competent flows together with the sediment deficit associated with the dams has led to less active fluvial environments (reduced particle mobility and bed scour dynamics), a fact that affects instream habitat structure (more uniform grain size distribution, less physical heterogeneity, more stable flows), overall contributing to the degradation of the stream corridor and the subsequent environmental deterioration of the whole fluvial landscape. Copyright © 2017 John Wiley & Sons, Ltd.     

Evaluation of Sediment Deposition in a Mediterranean Reservoir: Comparison of Long Term Bathymetric Measurements and SWAT Estimations

This study aims to demonstrate that the SWAT model can be used to predict discharge and sediment yield values in reservoir contributing catchments helping also to define the main factors that determine sedimentation rates in semi‐arid Mediterranean environments. This aim was achieved by comparing SWAT simulation results with water flows (over 29 years) and sediment deposition (over 47 years) volumes collected (by a campaign of bathymetric surveys) in a Sicilian reservoir. The mean monthly runoff coefficient calculated for the period 1980–2008 was 0·17. The mean sedimentation volume in the reservoir during the period 1963–2009 was 51,000 m³ year⁻¹. Field surveys and collection of spatially distributed databases of soil, topography and climate were carried out in order to characterize the contributing catchment. The SWAT model was applied to simulate sediment volumes cumulated over group of years as well as water flow volumes reaching annual and monthly the reservoir. The performance of the hydrological and erosion components of the model was evaluated by a combination of both summary and difference statistical measures after a sensitivity analysis and a calibration/validation process. The model was able to simulate observed runoff volumes at both annual and monthly scale. The mean sedimentation volume simulated by SWAT during the whole period was 8·1% lower than the value obtained by the bathymetric measurements (equal to 72·10³ Mg) with very good values of the efficiency coefficient (equal to 0·91). Copyright © 2016 John Wiley & Sons, Ltd.     

柴达木盆地东南部杨干透翅蛾与陕西榆林的差异研究

对柴达木盆地东南部的杨干透翅蛾（Sphecia siningensis）进行了调查研究,并研究了其与陕西榆林地区在形态特征、生活史和越冬虫态等方面的差别。     

Overwinter Mineralization of a Biosolid and Composted Banana Residues in Humid Mediterranean Conditions

The objectives of this work were to study nitrogen (N) release from a biosolid and a compost of banana wastes. The overwinter N decomposition was evaluated as the uptake by a cereal cover crop and the in situ losses from buried bags in a loamy sand (site 1) and in a calcareous silty clay loam (site 2). Organic materials were applied in two rates as sludge (1, 3.75 Mg ha^?1; 2, 7.5 Mg ha^?1) and compost (1, 3.29 Mg ha^?1; 2, 6.58 Mg ha^?1). Immediately after their incorporation in October, barley was planted as a cover crop. Its growth was negatively affected by the slow drainage of the silty clay loam, leading to greater N concentration in site 1 (21.18 g kg^?1 of barley versus 14.35 g kg^?1 of barley in site 2). Yet only 10% of the added N was intercepted by the cover crop in the fast-draining site 1. The ash-rich compost (N: 21.1 g kg^?1; ash: 467 g kg^?1) was comparable to the control. Within site 2, the biosolid treatments had a residual effect on a second barley crop, as N uptake was 1.99–2.13 times that of the control. The approach of in situ loss from bags incorporated in bare soil was repeated in two successive seasons. Nitrogen losses (% input) during the fall and winter months were comparable between sites 31.9 % (site 1) and 28.6 % (site 2). When the N fate was studied during the winter months only, the loss decreased slightly, suggesting the presence of a fraction liable to decomposition overwinter in Mediterranean conditions. Soil nitrate was determined 1 month after the incorporation of the cover crop in late spring. In the first season, only the sludge 2 treatment generated more nitrate than the control, whereas 19 months after the application of the organic products both sludge treatments had a positive effect. The soil properties influenced the amounts of N mineralized with site 1, yielding twice that of site 2. In the fast-draining soils, the presence of an active cover crop overwinter is necessary, while the N level of sludge 1 (164 kg N ha^?1) was more acceptable.     

Application of Fresh and Treated Pig Slurries and a Novel Organic-Mineral Fertilizer in Maize Crop

Lysimeter experiments were carried out during two growing seasons to compare the effect of untreated, digested, codigested, and a novel organic-mineral fertilizer, synthesized with pig slurry by a new-generation technology, on nitrogen (N) and phosphorus (P) leaching when compared with mineral fertilizer at typical rates for maize (Zea mays L.) production in Mediterranean soil. Relationships between application rates and type of fertilizer on maize crop yield, N uptake, and N and P leaching were investigated to assess the efficacy of these fertilizers in Mediterranean areas. Results showed a positive effect of the use of treated slurries, high N uptake of maize plants, and dry-matter production that was crucial for keeping N leaching loads at minimum. Then, not only in terms of production, but also in terms of N conservation in soil and in environmental water quality, slurries showed a better performance than inorganic or the organic-mineral fertilizer.     

太湖流域农村生活垃圾产排污系数测算研究

选取太湖流域典型农村9户农户（高、中、低收入水平各3户农户）作为研究对象,采用现场监测及入户调查的方法对农户生活垃圾污染物产排系数进行为期一年的系统定量研究,结果表明：收入水平对农户总垃圾、有机垃圾、有机垃圾TN、TP产排污系数及可回收垃圾产污系数影响极显著（P〈0.01）,具体表现为高收入农户〉中收入农户〉低收入农户,但对农户有害垃圾产排污系数及可回收垃圾排污系数无显著性影响（P〉0.05）。因此,除有害垃圾产排污系数及可回收垃圾排污系数外,农户总垃圾、有机垃圾、有机垃圾TN、TP产排污系数及可回收垃圾产污系数可按收入水平划分。各收入水平农户有机垃圾占总垃圾比例超过80%,表明有机垃圾的综合利用效率特别是畜禽养殖率是影响生活垃圾污染物排放系数的主导因素,而农业收入水平则对这种因素影响显著。     

Assessing Nitrogen Fertilization Strategies in Winter Wheat and Cotton Crops in Northern Greece

The management of fertilizer application is crucial for agricultural production and environmental safety.The objective of this study was to assess the effciency of different fertilization strategies,applying fertilizers with and without nitrification inhibitors(NIs) in split application,in Greece.The assessment criteria used were based on crop yield,soil nitrogen(N)concentrations and economic effciency.For this purpose two crops(winter wheat and cotton)were seffected in order to explore the optimum fertilization strategy for each crop.Three treatments combining fertilizers with NIs were tested compared with conventional fertilization(CF).Slight differences in the quantity and the combination of fertilizers with NIs applied resulted in variable effects on crop yield,soil N and economic return.Split N application of 102 kg ha^-1,with half of the total amount applied at seeding,resulted in higher grain yield of winter wheat,lower NO₃^--N in soil and higher economic return.This result reveals the importance of N application at seeding in wheat crop.Fertilization strategy with 109.5 kg N ha^-1 and split P application resulted in higher cotton yield and higher economic profit.Split P application seemed to increase yield,even though it is not a common practise in the area.     

滇东南弥勒盆地蓄水构造特征分析及找水方向

蓄水构造是富集地下水的地质构造形式,它是地下水形成、运动和蓄存的场所。在干旱地区寻找地下水主要是寻找有利的蓄水构造。通过分析弥勒盆地及其周边蓄水构造的特征,能为今后弥勒地区干旱年份寻找地下水提供水文地质依据。该文在对区域地质条件、地下水系统资料进行详尽分析并结合野外现场调查的基础上,基于蓄水构造的三要素,对滇东南弥勒盆地蓄水构造类型及其特征进行了分析,认为区内主要有汇水型蓄水构造、阻水型蓄水构造和风化带型蓄水构造三类,在干旱年份岩性分界面阻水型蓄水构造、断裂型蓄水构造和风化带型蓄水构造中的地下水具有供水意义。