Landscape approaches to the analysis of aquatic ecosystems

1. In the mid-1970s, Hynes (1975) wrote eloquently about the complex interactions between aquatic and terrestrial systems. Central theories in stream ecology developed thereafter have dealt with the longitudinal flow of energy, materials and organisms in streams, and, with the exception of the flood pulse concept (Junk, Bayley & Sparks, 1989), have largely ignored areas outside the riparian zone. The structure of the upland and activities occurring there play a more important part than previously recognized in regulating community structure and ecosystem processes in streams.
2. These new perspectives are made possible by developments in hierarchy theory, patch dynamics, and the refinement of tools used to quantify spatial and temporal heterogeneity.
3. Geographical information systems (GIS), image processing technology and spatial statistical techniques allow quantitative assessment of lateral, longitudinal and vertical components of the landscape that interact at several spatial and temporal scales to influence streams. When GIS is used in concert with geostatistics, multivariate statistics, or landscape models, complex relationships can be elucidated and predicted.
4. To a certain extent, the tools discussed above have only automated functions that were previously performed manually. This suite of tools has improved the ability of aquatic ecologists to examine relationships and test theories over larger, more heterogeneous regions than were previously possible.
5. At the local, state and federal level, management and regulatory frameworks are currently being re-evaluated to incorporate this new perspective in resource management and policy decision making.
6. We will discuss current and future trends in technologies and tools used for aquatic ecosystem research, and the use of techniques as they are applied in these regional assessments are also discussed.     

Reconciling landscape and local views of aquatic communities: lessons from Michigan trout streams

1. Rapidly advancing geographical information systems (GIS) technologies are forcing a careful evaluation of the roles and biases of landscape and traditional site-based perspectives on assessments of aquatic communities. Viewing the world at very different scales can lead to seeming contradictions about the nature of specific ecological systems. In the case of Michigan trout streams, landscape analyses suggest a predictable community shaped by large-scale patterns in hydrology and geology. Most site-based studies, however, suggest these communities are highly variable in structure over time, and are strongly shaped by site-specific physical and biological dynamics. As the real world is comprised of processes operating both at local and landscape scales, an analytical framework for integrating these paradigms is desirable.
2. Decomposition of variances by factorial ANOVA into time, space and time–space interaction terms can provide a conceptual and analytical model for integrating processes operating at landscape and local scales. Using this approach, long-term data sets were examined for three insects and two fishes common in Michigan trout streams. Each taxon had a unique variance structure, and the observed variance structure was highly dependent upon sample size.
3. Both spatially extensive designs with little sampling over time (typical of many GIS studies) and temporally extensive designs with little or no spatial sampling (typical of population and community studies), are biased in terms of their view of the relative importance of local and landscape factors. The necessary, but in many cases costly, solution is to develop and analyse data sets that are both spatially and temporally extensive.     

Reconciling landscape and local views of aquatic communities: lessons from Michigan trout streams

1. Rapidly advancing geographical information systems (GIS) technologies are forcing a careful evaluation of the roles and biases of landscape and traditional site-based perspectives on assessments of aquatic communities. Viewing the world at very different scales can lead to seeming contradictions about the nature of specific ecological systems. In the case of Michigan trout streams, landscape analyses suggest a predictable community shaped by large-scale patterns in hydrology and geology. Most site-based studies, however, suggest these communities are highly variable in structure over time, and are strongly shaped by site-specific physical and biological dynamics. As the real world is comprised of processes operating both at local and landscape scales, an analytical framework for integrating these paradigms is desirable.
2. Decomposition of variances by factorial ANOVA into time, space and time–space interaction terms can provide a conceptual and analytical model for integrating processes operating at landscape and local scales. Using this approach, long-term data sets were examined for three insects and two fishes common in Michigan trout streams. Each taxon had a unique variance structure, and the observed variance structure was highly dependent upon sample size.
3. Both spatially extensive designs with little sampling over time (typical of many GIS studies) and temporally extensive designs with little or no spatial sampling (typical of population and community studies), are biased in terms of their view of the relative importance of local and landscape factors. The necessary, but in many cases costly, solution is to develop and analyse data sets that are both spatially and temporally extensive.     

Spatial and temporal modelling for parasite transmission studies and risk assessment

Spatial and temporal modelling of parasite transmission and risk assessment require relevant spatial information at appropriate spatial and temporal scales. There is now a large literature that demonstrates the utility of satellite remote sensing and spatial modelling within geographical information systems (GIS) and firmly establishes these technologies as the key tools for spatial epidemiology. This review outlines the strength of satellite remotely sensed data for spatial mapping of landscape characteristics in relation to disease reservoirs, host distributions and human disease. It is suggested that current satellite technology can fulfill the spatial mapping needs of disease transmission and risk modelling, but that temporal resolution, which is a function of the satellite data acquisition characteristics, may be a limitating factor for applications requiring information about landscape or ecosystem dynamics. The potential of the Modis sensor for spatial epidemiology is illustrated with reference to mapping spatial and temporal vegetation dynamics and small mammal parasite hosts on the Tibetan plateau. Future research directions and priorities for landscape epidemiology are considered.     

The fauna of dynamic riverine landscapes

1.  Riverine landscapes are heterogeneous in space (complex mosaic of habitat types) and time (expansion and contraction cycles, landscape legacies). They are inhabited by a diverse and abundant fauna of aquatic, terrestrial and amphibious species.
2.  Faunal distribution patterns are determined by interactive processes that reflect the landscape mosaic and complex environmental gradients. The life cycles of many riverine species rely upon a shifting landscape mosaic and other species have become adapted to exploit the characteristically high turn-over of habitats.
3.  The complex landscape structure provides a diversity of habitats that sustains various successional stages of faunal assemblages. A dynamic riverine landscape sustains biodiversity by providing a variety of refugia and through ecological feedbacks from the organisms themselves (ecosystem engineering).
4.  The migration of many species, aquatic and terrestrial, is tightly coupled with the temporal and spatial dynamics of the shifting landscape mosaic. Alternation of landscape use by terrestrial and aquatic fauna corresponds to the rise and fall of the flood. Complex ecological processes inherent to intact riverine landscapes are reflected in their biodiversity, with important implications for the restoration and management of river corridors.     

Macroinvertebrate diversity in headwater streams: a review

1. Headwater streams are ubiquitous in the landscape and are important sources of water, sediments and biota for downstream reaches. They are critical sites for organic matter processing and nutrient cycling, and may be vital for maintaining the 'health' of whole river networks.
2. Macroinvertebrates are an important component of biodiversity in stream ecosystems and studies of macroinvertebrate diversity in headwater streams have mostly viewed stream systems as linear reaches rather than as networks, although the latter may be more appropriate to the study of diversity patterns in headwater systems.
3. Studies of macroinvertebrate diversity in headwater streams from around the world illustrated that taxonomic richness is highly variable among continents and regions, and studies addressing longitudinal changes in taxonomic richness of macroinvertebrates generally found highest richness in mid-order streams.
4. When stream systems are viewed as networks at the landscape-scale, α-diversity may be low in individual headwater streams but high β-diversity among headwater streams within catchments and among catchments may generate high γ-diversity.
5. Differing ability and opportunity for dispersal of macroinvertebrates, great physical habitat heterogeneity in headwater streams, and a wide range in local environmental conditions may all contribute to high β-diversity among headwater streams both within and among catchments.
6. Moving beyond linear conceptual models of stream ecosystems to consider the role that spatial structure of river networks might play in determining diversity patterns at the landscape scale is a promising avenue for future research.     

Riverine landscapes: taking landscape ecology into the water

1. Landscape ecology deals with the influence of spatial pattern on ecological processes. It considers the ecological consequences of where things are located in space, where they are relative to other things, and how these relationships and their consequences are contingent on the characteristics of the surrounding landscape mosaic at multiple scales in time and space. Traditionally, landscape ecologists have focused their attention on terrestrial ecosystems, and rivers and streams have been considered either as elements of landscape mosaics or as units that are linked to the terrestrial landscape by flows across boundaries or ecotones. Less often, the heterogeneity that exists within a river or stream has been viewed as a `riverscape' in its own right.
2. Landscape ecology can be unified about six central themes: (1) patches differ in quality (2) patch boundaries affect flows, (3) patch context matters, (4) connectivity is critical, (5) organisms are important, and (6) the importance of scale. Although riverine systems differ from terrestrial systems by virtue of the strong physical force of hydrology and the inherent connectivity provided by water flow, all of these themes apply equally to aquatic and terrestrial ecosystems, and to the linkages between the two.
3. Landscape ecology therefore has important insights to offer to the study of riverine ecosystems, but these systems may also provide excellent opportunities for developing and testing landscape ecological theory. The principles and approaches of landscape ecology should be extended to include freshwater systems; it is time to take the `land' out of landscape ecology.     

宏观生态学研究的特点与方法

宏观生态学是研究生态系统以上层次的生态学,研究对象为大尺度复杂系统,研究内容和方法都具有不同于传统生态学的明显特点。重视对空间异质性的研究,重视人类的生态作用,注意运用等级结构理论,其研究结果常常是非实验性和非稳定性的。遥感和地理信息系统是空间数据采集和管理、分析的主要手段,景观分析和景观模型是宏观生态研究的重要方法,定位观测试验的网络研究则是实现宏观整体研究的必由之路。     

The use of geographic information systems to map and assess ecosystem services

In recent years, geographic information systems (GIS) have become a powerful tool for mapping and assessing the provision of ecosystem services within a landscape. GIS can help land managers and conservationists visualize spatial and temporal patterns and changes in ecosystem services and estimate the potential impact from projected changes in land use or management or climatic conditions on the provision of these services. The end-goal of ecosystem service assessment is usually to estimate marginal values of ecosystem services to inform decisions where trade-offs in ecosystem service provision will affect human well-being. Because our ability to estimate the provision of ecosystem services underlies our ability to estimate their societal values, the theoretical bases of GIS approaches and models for assessing ecosystem services need to be well understood before they are employed for decision-making purposes. This paper reviews GIS approaches and software developed for the assessment of ecosystem services and highlights their strengths and weaknesses in the context of different end uses.     

生态功能区划理论研究进展

作为生态系统管理的重要手段,开展科学合理的生态功能区划,已成为世界各国走向可持续发展所面临的关键挑战之一。生态功能区划针对一定区域内自然地理环境分异性、生态系统多样性、以及经济与社会发展不均衡性的现状,结合自然资源保护和可持续开发利用的思想,整合与分异生态系统服务功能对区域人类活动影响的生态敏感性,将区域空间划分为不同生态功能区的研究过程。生态功能区划反映了基于景观特征的主要生态模式,强调了不同时空尺度的景观异质性。通过梳理生态功能区划的概念与内涵、形成与发展及其理论基础,提出了生态功能区划是以恢复区域持续性、完整性的生态系统健康为目标,基于区域的自然地理背景,界定生态功能分区及其子系统的边界,结合区域水陆生态系统、社会经济与土地利用的现状评价与问题诊断,识别生态系统空间格局的分布特征、生态过程的关键因子以及动态演替的驱动因子,明确影响生态系统服务功能的景观格局与结构、景观过程与功能以及景观动态变化,构建生态功能区划的指标体系与技术体系,实现生态功能多级区划,并为决策者更为全面和综合地开展生态系统管理提供科学依据。     

Fluvial landscape ecology: addressing uniqueness within the river discontinuum

1. As rivers and streams are patchy and strongly hierarchical systems, a hierarchical patch dynamics perspective can be used as a framework for visualising interactions between structure and function in fluvial landscapes. The perspective is useful for addressing fundamental attributes of lotic ecosystems, such as heterogeneity, hierarchy, directionality and process feedback occurring across spatial scales and for illustrating spatio‐temporal linkages between disparate concepts in lotic system ecology such as the River Continuum Concept, the Serial Discontinuity Concept, the Flood Pulse Concept and the Hyporheic Corridor Concept. 2. At coarse spatial scales, the hierarchical patch dynamics perspective describes each river network as a unique, patchy discontinuum from headwaters to mouth. The discontinuum is comprised of a longitudinal series of alternating stream segments with different geomorphological structures. Each confluence in the steam network further punctuates the discontinuum because the sudden change in stream characteristics can create a `gap' in the expected pattern of downstream transitions. The discontinuum view recognises general trends in habitat characteristics along the longitudinal profile, but creates a framework for studying and understanding the ecological importance of each stream's individual pattern of habitat transitions along longitudinal, lateral or vertical vectors at any scale. 3. Object‐oriented modelling and programming techniques provide a means for developing robust, quantitative simulation models that describe the dynamic structure of patch hierarchies. Such models can simulate how the structure and function of lotic ecosystems are influenced by the landscape context of the system (the ecological conditions within which the system is set) and the metastructure (structural characteristics and juxtaposition) of finer‐scale patches comprising the system. 4. A simple object‐oriented, multiscale, discontinuum model of solute transformation and biological response along a stream channel illustrates how changing the branching pattern of a stream and the arrangement of its component patches along the downstream profile will result in substantial changes in predicted patterns of solute concentration and biotic community structure. 5. The importance of context, structure, and metastructure in determining lotic ecosystem function serves to underscore 27 ) concept that `every stream is likely to be individual.' Advancing the discipline of fluvial landscape ecology provides an excellent opportunity to develop general concepts and tools that address the individual character of each stream network and integrate the concept of `uniqueness within the river discontinuum' into our ecological understanding of rivers and streams.     

Ecosystem based modeling and indication of ecological integrity in the German North Sea—Case study offshore wind parks

Human exploitation and use of marine and coastal areas are apparent and growing in many regions of the world. For instance, fishery, shipping, military, raw material exploitation, nature protection and the rapidly expanding offshore wind power technology are competing for limited resources and space. The development and implementation of Integrated Coastal Zone Management (ICZM) strategies could help to solve these problems. Therefore, suitable spatial assessment, modeling, planning and management tools are urgently needed. These tools have to deal with data that include complex information on different spatial and temporal scales. A systematic approach based on the development of future scenarios which are assessed by combining different simulation models, GIS methods and an integrating set of ecological integrity indicators, was applied in a case study in the German North Sea. Here, the installation of huge offshore wind parks within the near future is planned. The aim was to model environmental effects of altered sea-use patterns on marine biota. Indicators of ecological integrity were used to assess altering conditions and possible ecosystem shifts ranging from systems’ degradations to the development of highly productive and diverse artificial reef systems. The results showed that some ecosystem processes and properties and related indicators are sensitive to changes generated by offshore wind park installations while others did not react as hypothesized.     

矿区生态风险评价研究述评

作为世界上矿产资源最丰富的国家之一,我国的矿山开采活动在给经济发展注入强大拉动力的同时,也给矿区生态环境带来了巨大的生态风险。总结前人相关研究,在对比分析了矿区生态风险及其评价与区域生态风险评价异同的基础上,初步明晰矿区生态风险具有风险源的多样性、空间影响边界的模糊性、随空间距离的衰减性及时间累积的延续性等特性。目前矿区生态风险评价的矿区类型过多集中于金属矿区的重金属污染等单项风险,对综合生态风险评价的重视不充分,多基于景观格局、生态环境问题视角,结果多对斑块或生态系统风险评价进行拼接,欠缺基于空间异质性的整体综合;风险度量模型、指标体系法和空间分析法则是较为常用的矿区生态风险评价方法,但在模型模拟方面略显不足。基于现有研究进展,预期矿区独特性的体现、空间格局的关注、"3S"技术的综合应用、生态安全阈值的设定、不确定性表征、基于评价结果的风险规避等将有望成为未来研究的重点。     

Regional-Level Inputs of Emergent Aquatic Insects from Water to Land

Emergent aquatic insects can provide inputs to terrestrial ecosystems near lentic and lotic waterbodies, producing ecosystem linkages at the aquatic–terrestrial interface. Although aquatic insect emergence has been examined for individual sites, the magnitude and spatial distribution of this phenomenon has not been examined at regional spatial scales. Here, we characterize this cross-habitat linkage for the state of Wisconsin, USA (169,639 km²). We combined GIS hydrological data with empirical data and predictive models of aquatic insect production to estimate annual aquatic emergence for the state of Wisconsin. Total emergence (lentic + lotic) was estimated to be about 6,800 metric tons of C y^?1. Lentic systems comprised 79% of total estimated insect emergence, primarily due to the large amount of lake surface area relative to streams. This is due to both basic ecosystem geometry and the overall abundance of lakes in Wisconsin. Spatial variation was high: insect emergence in southwestern Wisconsin was dominated by streams, whereas for most of the rest of the state insect emergence was dominated by lakes. Lentic inputs to land were highly concentrated (relative to lotic inputs) because lakes have a high ratio of surface area to buffer area. Although less concentrated, the spatial extent of lotic influence was greater: statewide, four times more land area fell within the 100 m buffer zones of streams compared to lakes. Large waterbodies (almost all of which were lakes) were hotspots of insect emergence and input to land. Aquatic insect inputs exceed estimated terrestrial secondary production in 13% of buffer area, and by a factor of 100 or more adjacent to large lakes (>50,000 ha). The model sensitivity analysis showed that the simplifying assumptions and sources of potential error in the input variables had a minor impact on the overall results.     

Free and open source geographic information tools for landscape ecology

Geographic Information tools (GI tools) have become an essential component of research in landscape ecology. In this article we review the use of GIS (Geographic Information Systems) and GI tools in landscape ecology, with an emphasis on free and open source software (FOSS) projects. Specifically, we introduce the background and terms related to the free and open source software movement, then compare eight FOSS desktop GIS with proprietary GIS to analyse their utility for landscape ecology research. We also provide a summary of related landscape analysis FOSS applications, and extensions. Our results indicate that (i) all eight GIS provide the basic GIS functionality needed in landscape ecology, (ii) they all facilitate customisation, and (iii) they all provide good support via forums and email lists. Drawbacks that have been identified are related to the fact that most projects are relatively young. This currently affects the size of their user and developer communities, and their ability to include advanced spatial analysis functions and up-to-date documentation. However, we expect these drawbacks to be addressed over time, as systems mature. In general, we see great potential for the use of free and open source desktop GIS in landscape ecology research and advocate concentrated efforts by the landscape ecology community towards a common, customisable and free research platform.     

景观对河流生态系统的影响

从景观的视角研究河流生态系统,是目前河流生态学中受到广泛关注且发展迅速的内容之一。流域内多尺度景观强烈影响河流的理化及生物特征,已成为共识,但有关量度、整合景观与河流生态系统二者之间联系的理论体系与方法的建立尚处于起步阶段。对景观组成与空间格局影响河流生态系统的机制与途径进行了系统总结,提出了该领域研究中的主要难题,即如何识别景观中人为因素和自然因素的协变现象,如何衡量多空间尺度景观对河流生态系统的交互影响,如何理解景观阈值的不确定性。为克服当前研究面临的困难与挑战,填补已有知识的不足,提出今后研究的重点方向:河流景观分类系统的改进;更具代表性时空数据的采集;新型景观指标的开发与应用;微观尺度数据与宏观尺度数据的整合等。     

Critical landscape attributes that influence fish population dynamics in headwater streams

Three landscape attributes are likely to have strong effects on the rate-dependent processes determining fish population dynamics in headwater streams: (1) functional interactions at terrestrial-aquatic ecotones and their influence on temporal and spatial variation in resource supply and predator-prey interactions, (2) large-scale spatial habitat relationships and their effect on resource use and fish movement, and (3) presence of refugia from harsh environmental conditions and their influence on fish survival and emigration/immigration rates. Elucidating how these factors interact over a range of temporal and spatial scales should be a major goal of lotic fish ecologists.     

Ecological Thresholds: The Key to Successful Environmental Management or an Important Concept with No Practical Application?

An ecological threshold is the point at which there is an abrupt change in an ecosystem quality, property or phenomenon, or where small changes in an environmental driver produce large responses in the ecosystem. Analysis of thresholds is complicated by nonlinear dynamics and by multiple factor controls that operate at diverse spatial and temporal scales. These complexities have challenged the use and utility of threshold concepts in environmental management despite great concern about preventing dramatic state changes in valued ecosystems, the need for determining critical pollutant loads and the ubiquity of other threshold-based environmental problems. In this paper we define the scope of the thresholds concept in ecological science and discuss methods for identifying and investigating thresholds using a variety of examples from terrestrial and aquatic environments, at ecosystem, landscape and regional scales. We end with a discussion of key research needs in this area.