Spatiotemporal patterns of mountain whitefish (Prosopium williamsoni) in response to a restoration of longitudinal connectivity          下载免费PDF全文

Peter M. Kiffney  Ben Cram  Paul L. Faulds  Karl Burton  Michele Koehler  Thomas P. Quinn 《Ecology of Freshwater Fish》2018,27(4):1037-1053

To examine the role of longitudinal connectivity on the spatial and temporal dynamics of mountain whitefish (Prosopium williamsoni), we quantified movement and population dynamics following installation of the Landsburg Dam fishway, Cedar River, WA, USA. Mountain whitefish is widely distributed, poorly studied and not the focus of restoration. Before the fishway, mountain whitefish were not observed above the dam. Here, we focus on snorkel counts collected at reach and mesohabitat (e.g. pools) scales over 11 summers on the 20‐km above‐dam segment following restoration. A camera within the ladder provided number, size and movement timing, thereby informing on behaviour and recolonisation. Segment‐scale abundance increased following fish passage reaching an asymptote in 7 years, and mountain whitefish were detected throughout the main stem in 10 years. Annual movement through the ladder increased over time and was positively correlated with instream abundance and discharge, but negatively correlated with water temperature. About 60% of fish movements occurred in spring and early summer, potentially for foraging opportunities. Reach‐scale abundance peaked between 7 and 10 km from the dam; deep, cool (~10.6 to 11.6°C) conditions characterised these reaches. At the mesohabitat scale, mountain whitefish detection increased with depth and velocity after accounting for distance from the dam. Our results show how restoring longitudinal connectivity allowed this nontarget species to colonise newly available habitat. Their response supports the critical roles of longitudinal connectivity and environmental conditions, that manifest at different spatial scales, in dictating how freshwater fish respond to habitat disturbance.  相似文献   

Population dynamics and habitat connectivity affecting the spatial spread of populations – a simulation study     

Söndgerath  Dagmar  Schröder  Boris 《Landscape Ecology》2002,17(1):57-70

In this paper we show how the spatialconfiguration of habitat quality affects the spatial spread of apopulation in a heterogeneous environment. Our main result is thatfor species with limited dispersal ability and a landscape withisolated habitats, stepping stone patches of habitat greatlyincrease the ability of species to disperse. Our results showthat increasing reproductive rate first enables and thenaccelerates spatial spread, whereas increasing the connectivity has aremarkable effect only in case of low reproductive rates. Theimportance of landscape structure varied according to thedemographic characteristics of the population. To show this wepresent a spatially explicit habitat model taking into accountpopulation dynamics and habitat connectivity. The population dynamicsare based on a matrix projection model and are calculated on eachcell of a regular lattice. The parameters of the Leslie matrix dependon habitat suitability as well as density. Dispersal between adjacentcells takes place either unrestricted or with higher probability inthe direction of a higher habitat quality (restricted dispersal).Connectivity is maintained by corridors and stepping stones ofoptimal habitat quality in our fragmented model landscape containinga mosaic of different habitat suitabilities. The cellular automatonmodel serves as a basis for investigating different combinations ofparameter values and spatial arrangements of cells with high and lowquality.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

A Fast One-Step Scanning Thinning Algorithm     

Wu xiaoyun  Zhang Taiyi  Liu Pin 《保鲜与加工》1994,(3):13-17

A new quick thinning algorithm was presented in this paper,which assigneddifferent weights to different pixels near the skeleton pixels and rules out the im possible pixels in thethinning procedure. It needs neither iteration on pixel panel nor detection on every pixel such thatthe time consumed is greatly lessened. A filling algorithm is also offered for better results.Experiment on variety of binary patterns showed that it could get both a high speed and a goodskeleton shape compared with other algorithms,This new algorithm reaches perfect result.  相似文献   

Assemblage patterns of fish functional groups relative to habitat connectivity and conditions in floodplain lakes     

S. Miyazono  J. N. Aycock  L. E. Miranda  T. E. Tietjen 《Ecology of Freshwater Fish》2010,19(4):578-585

Miyazono S, Aycock JN, Miranda LE, Tietjen TE. Assemblage patterns of fish functional groups relative to habitat connectivity and conditions in floodplain lakes.
Ecology of Freshwater Fish 2010: 19: 578–585. © 2010 John Wiley & Sons A/S Abstract – We evaluated the influences of habitat connectivity and local environmental factors on the distribution and abundance patterns of fish functional groups in 17 floodplain lakes in the Yazoo River Basin, USA. The results of univariate and multivariate analyses showed that species–environmental relationships varied with the functional groups. Species richness and assemblage structure of periodic strategists showed strong and positive correlations with habitat connectivity. Densities of most equilibrium and opportunistic strategists decreased with habitat connectivity. Densities of certain equilibrium and opportunistic strategists increased with turbidity. Forested wetlands around the lakes were positively related to the densities of periodic and equilibrium strategists. These results suggest that decreases in habitat connectivity, forested wetland buffers and water quality resulting from environmental manipulations may cause local extinction of certain fish taxa and accelerate the dominance of tolerant fishes in floodplain lakes.  相似文献   

European eel distribution and body condition in a river floodplain: effect of longitudinal and lateral connectivity     

E. Lasne  A. Acou  A. Vila‐Gispert  P. Laffaille 《Ecology of Freshwater Fish》2008,17(4):567-576

Abstract – We studied eel population characteristics (size classes, densities and body condition) in the lower Loire River floodplain (France) to evaluate the effects of longitudinal and lateral gradients. A total of 36 sites were electrofished in June 2005. The sites were grouped first into three river segments according to the distance inland corresponding to a longitudinal gradient and secondly into three lateral connectivity categories. Results indicate that small eels, especially those ≤300 mm, were very abundant downstream but density rapidly decreased upstream. In addition, eels ≤150 mm tended to be most abundant in connected waterbodies. Conversely, the distribution of larger eels was quite uniform across both dimensions. Eel condition decreased upstream. In parallel, in downstream river segment, eels had a lower condition in disconnected waterbodies than in connected ones. Eel specialists still have only a longitudinal perception of eel habitat. Our results suggest that lateral gradients should be also taken into consideration.  相似文献   

引入耕地生态价值的咸阳市基本农田划定     

李丁一  魏舟  童亚文  李莹莹  周传龙  张青峰 《农业工程学报》2023,39(16):256-265

为了探索科学客观的基本农田划定方法,实现将集中连片和优质稳定的耕地划为基本农田的目标,有效保护耕地和保障国家农业生产安全。该研究以陕西省咸阳市为例,引入耕地生态价值和政策条件多维度评价耕地质量,结合耕地质量空间集聚类型划定耕地保护分区;采用缓冲区分析法识别耕地连片性,耦合耕地保护分区和耕地连片等级,尝试探索“连片优先、质量优良、数量约束”的基本农田划定流程。结果表明:1)咸阳市耕地质量划分为高、较高、一般、较低、低5个等级,全市超过一半面积的耕地质量等级为低和较低等级(35.81%和29.67%),一般和较高等级的耕地面积占比也均超过了10%;不同耕地质量等级在空间分布上的差异受地形和区域经济发展影响较大,耕地质量等级总体上呈现出“南高北低”的空间分布格局;咸阳市耕地质量在空间上呈现出明显的集聚特征,以高-高值集聚型和低-低值集聚型耕地为主;2)将全市耕地划为优先保护区、适宜保护区、重点整治区和全面治理区4个保护分区并提出一些保护建议。全面治理区内耕地面积最多,占全市耕地总面积的35.50%,适宜保护区内耕地面积最少,仅占11.81%;3)咸阳市共得到49 713个耕地连片地块,面积2...  相似文献   

Urbanization Development under Climate Change: Hydrological Responses in a Peri‐Urban Mediterranean Catchment     

《Land Degradation \u0026amp; Development》2017,28(7):2207-2221

Relatively few studies have so far investigated the hydrological impacts of urbanization in Mediterranean catchments, and particularly in peri‐urban catchments experiencing relatively rapid and large changes in their land‐use mosaic. This study uses data‐based model simulations to investigate such impacts, with the Ribeira dos Covões catchment in Portugal as a concrete Mediterranean peri‐urban catchment example. We distinguish the impacts of urbanization from those of climatic change on the water flux partitioning and connectivity in the catchment over the period 1958–2013. Decrease in precipitation over this period has primarily driven decreases in annual runoff and actual evapotranspiration, while the urbanization development has primarily changed the relative flux partitioning and connectivity pattern in the catchment. The relative contribution of overland flow to annual and seasonal runoff has increased, keeping the absolute overland flow more or less intact, while the baseflow contribution to the stream network has decreased. Methodologically, the present simulation approach provides a relevant means for distinguishing main drivers of change in hydrological flux partitioning and connectivity under concurrent urbanization and climatic changes. © 2017 The Authors. Land Degradation & Development Published by John Wiley & Sons Ltd.  相似文献   

基于水文连通性的流域输沙量评估——以堵河流域为例     

张媛平  刘成帅  肖海兵  王剑  史志华 《水土保持研究》2022,29(3):64-70

水文连通性是指泥沙、营养盐等各种物质以水为载体,在空间异质景观或斑块间进行迁移、传输或扩散的便利程度,对流域产沙具有重要影响。为评估基于水文连通性模拟流域输沙量的可行性,以堵河流域为研究对象,分析了1990—2010年流域土壤侵蚀、水文连通性的时空变化特征,并以此估算了流域输沙量。结果表明:1990—2000年流域土壤侵蚀模数与连通程度不断增加,连通性等级主要由低和中低连通性转变为中高和高连通性。2000—2010年流域连通程度和土壤侵蚀模数均呈现不断减小的趋势。此外,输沙量估算值与实测值具有显著的线性关系(R²=0.92),但由于未考虑水库、湖泊等对泥沙输移的拦截效应,输沙量估算值要高于实测值,后续研究需将其纳入模型以更准确地评估流域输沙量。研究结果对于提高模型的适用性以及理解流域泥沙输移过程具有重要意义。  相似文献   

Soil aeration and redox potential as function of pore connectivity unravelled by X-ray microtomography imaging     

Kristof Dorau  Daniel Uteau  Maren Pia Hövels  Stephan Peth  Tim Mansfeldt 《European Journal of Soil Science》2022,73(1):e13165

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Taxonomic and functional macroinvertebrate diversity of high-altitude ponds in the Macun Cirque,Switzerland     

Matthew J. Hill  Paul J. Wood  Kate L. Mathers 《水产资源保护:海洋与淡水生态系统》2021,31(11):3201-3214

1. Global environmental change is threatening freshwater biodiversity with ecological impacts predicted to be particularly severe in high-altitude regions. Despite this, an ecological understanding of high-altitude pond networks remains patchy, with only limited knowledge of the environmental and spatial predictors of taxonomic and functional diversity. Moreover, previous studies of pond ecosystems have focused primarily on taxonomic richness and largely overlooked functional diversity.
2. This study examined the influence of local environmental and spatial factors on taxonomic and functional α and β diversity (including the turnover and nestedness-resultant components) of 17 high-altitude (~2,500 m above sea level) pond macroinvertebrate communities, in the Macun Cirque, Switzerland.
3. Spatial processes (pond connectivity) were important drivers for taxonomic α diversity, while local environmental variables (pond permanence and surface area) were important determinants of functional α diversity. Species turnover was the most important component of β diversity for taxonomic composition, and functional composition demonstrated a nested spatial pattern.
4. Variation in taxonomic and functional composition (and the turnover and nestedness components of β diversity) were determined by local environmental variables despite the limited environmental gradients within the pond network. No significant effects of spatial variables on community composition were recorded for either facet of diversity, indicating that compositional variation was determined at a local scale. Water temperature, depth and pond permanence were consistently the most important measured drivers of diversity.
5. Given the importance of both spatial and environmental variables in structuring taxonomic and functional diversity, landscape-scale conservation and management activities that aim to improve or protect high-altitude freshwater biodiversity should focus on maintaining connectivity among ponds and environmental heterogeneity, particularly pond surface area, water depth, and hydroperiod. Understanding the mechanisms driving taxonomic and functional diversity will be critically important for the management and conservation of macroinvertebrate communities in high-altitude pond networks in the face of climatic warming.

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