Monitoring Urban Streams: Strategies and Protocols for Humid-Region Lowland Systems

Governmental mandates and public awareness have forcedprogressively smaller and less sophisticated agencies andorganizations to initiate stream monitoring programs,particularly in urban and urbanizing areas. Yet many of thesemonitoring efforts lack either a coherent conceptual frameworkor appropriately chosen methods, and they rely on monitoringtechniques that are simply infeasible for these institutionalsettings. We propose a monitoring strategy, and specificexisting monitoring protocols, that will be useful for themanagement and rehabilitation of streams in urbanizing watersheds.A monitoring strategy must be developed by 1) identifying the management question(s) being addressed, 2) determining theinstitional level of effort required (and available) toeffectively make particular kinds of measurements, and 3) identifying what specific parameters should and can be measured.Only a limited set of parameters show much utility orfeasibility in addressing the most common management questionsbeing faced by municipalities in urbanizing, humid-area regionsof the United States. These include measures of riparian canopy,bank erosion and bank hardening, and in-stream large woodydebris. With some additional expertise useful data can also beincluded on channel gradient, substrate composition, and pools.Nearly all of the other myriad parameters that have beenmeasured historically on rivers and streams show little apparentvalue in these watershed and institutional settings.     

Instream Flow Science For Sustainable River Management1

Abstract: Concerns for water resources have inspired research developments to determine the ecological effects of water withdrawals from rivers and flow regulation below dams, and to advance tools for determining the flows required to sustain healthy riverine ecosystems. This paper reviews the advances of this environmental flows science over the past 30 years since the introduction of the Instream Flow Incremental Methodology. Its central component, Physical HABitat SIMulation, has had a global impact, internationalizing the e‐flows agenda and promoting new science. A global imperative to set e‐flows, including an emerging trend to set standards at the regional scale, has led to developments of hydrological and hydraulic approaches but expert judgment remains a critical element of the complex decision‐making process around water allocations. It is widely accepted that river ecosystems are dependent upon the natural variability of flow (the flow regime) that is typical of each hydro‐climatic region and upon the range of habitats found within each channel type within each region. But as the sophistication of physical (hydrological and hydraulic) models has advanced emerging biological evidence to support those assumptions has been limited. Empirical studies have been important to validate instream flow recommendations but they have not generated transferable relationships because of the complex nature of biological responses to hydrological change that must be evaluated over decadal time‐scales. New models are needed to incorporate our evolving knowledge of climate cycles and morphological sequences of channel development but most importantly we need long‐term research involving both physical scientists and biologists to develop new models of population dynamics that will advance the biological basis for 21st Century e‐flow science.     

青藏高原东部生态系统土壤碳排放

在青藏高原探讨不同生态系统碳平衡规律及其影响因子并揭示其对全球含碳温室气体变化的影响与响应,有重要的现实意义和理论价值。分别在海北高寒草甸生态站、贡嘎山森林生态站和拉萨农业生态站用静态箱法进行了土壤CO₂排放的试验研究。土壤CO₂排放速率日平均值为草甸215.87～329.68mgCO₂m^-2h^-1,森林713.72～2102.56mgCO₂m^-2h^-1,农田913.05～1135.83mgCO₂m^-2h^-1。土壤碳排放速率日变化,在农田和高寒草甸区表现为单峰型,均以地方时8∶00～16∶00最高,0∶00～8∶00最低。草甸、农田土壤碳排放随着牧草、作物生长发育的加速而逐渐增加,越接近成熟(或枯黄期)其值越低,林区以6～9月的生长旺季为最高。土壤碳排放与温度之间有较好的相关性,温度是影响土壤碳排放的重要因子,全球变暖有可能引起高原土壤碳排放的增加。     

森林生态系统在碳循环中的作用

描述了森林生态系统的碳循环及其在全球碳循环中的作用，说明了森林生态系统在碳循环中的作用主要取决于森林生态系统的生物量、林产品、植物枯枝落叶和根系碎屑以及森林土壤。最后，阐明了中国森林生态系统碳循环的研究现状和趋势。     

基于属性理论的长株潭城市群生态系统健康评价

城市生态系统是一种高度人工化的自然-社会-经济复合生态系统,其健康状况直接影响到城市的可持续发展。针对城市生态系统健康评价标准的不确定性问题,在构建评价指标体系的基础上,提出了基于属性理论的城市生态系统健康评价模型及评价方法。以长株潭城市群为研究区域,运用该模型和方法对其生态系统健康进行了综合评价。评价结果表明：长株潭城市群的生态系统现状属于一般健康类,其中自然生态子系统对区域整体健康状况有较大影响,评价结果与实际情况大体吻合。通过对各子系统层的健康度分析,识别了健康限制因素,并提出了相应的调控措施。采用属性理论方法开展城市生态系统健康评价,能较好地识别系统层综合健康状况和子系统层的健康状况,具有一定的实用价值,其评价结果为促进城市生态建设,有效实施生态系统健康管理提供了科学依据。     

Alternatives to biodiversity offsets for mitigating the effects of urbanization on stream ecosystems

Globally, offset schemes have emerged in many statutory frameworks relating to development activities, with the aim of balancing biodiversity conservation and development. Although the theory and use of biodiversity offsets in terrestrial environments is broadly documented, little attention has been paid to offsets in stream ecosystems. Here we examine the application of offset schemes to stream ecosystems and explore whether they suffer similar shortcomings to those of offset schemes focused on terrestrial biodiversity. To challenge the applicability of offsets further, we discuss typical trajectories of urban expansion and their cascading physical, chemical and biological impacts on stream ecosystems. We argue that the highly connected nature of stream ecosystems and urban drainage networks can transfer impacts of urbanization across wide areas, complicating the notion of like‐for‐like exchange and the prospect of effectively mitigating biodiversity loss. Instead, we identify in‐catchment options for stormwater control, which can avoid or minimize the impacts of development on downstream ecosystems, while presenting additional public and private benefits. We describe the underlying principles of these alternatives, some of the challenges associated with their uptake, and policy initiatives being trialed to facilitate adoption. In conclusion, we argue that stronger policies to avoid and minimize the impacts of urbanization provide better prospects for protecting downstream ecosystems, and can additionally, stimulate economic opportunities and improve urban liveability.     

PROCESS DOMAINS AND THE RIVER CONTINUUM1

ABSTRACT: The concept of process domains is proposed as an alternative to the River Continuum Concept for the influence of geomorphic processes on aquatic ecosystems. Broadly defined, the Process Domain Concept is a multi-scale hypothesis that spatial variability in geomorphic processes governs temporal patterns of disturbances that influence ecosystem structure and dynamics. At a coarse scale, regional climate, geolog vegetation, and topography control the suite of geomorphic processes that are distributed over a landscape. Within the broad context so defined, stream channel classification can guide identification of functionally similar portions of a channel network, but the response of otherwise similar reaches can depend upon their geologic and geomorphic context. Within geomorphic provinces defined by differences in topography, climate history, and tectonic setting, areas with generally similar geology and topography define lithotopo units, which are useful for stratifying different suites of dominant geomorphic processes. Process domains are spatially identifiable areas characterized by distinct suites of geomorphic processes, and the Process Domain Concept implies that channel networks can be divided into discrete regions in which community structure and dynamics respond to distinctly different disturbance regimes. The concepts of process domains and lithotopo units provide both a framework for the application of patch dynamics concepts to complex landscapes and a context for addressing the effects of watershed processes on the ecology of mountain drainage basins.     

THE (POLITICAL) SCIENCE OF WATERSHED MANAGEMENT IN THE ECOSYSTEM AGE1

ABSTRACT: Ecosystem management has become an important unifying theme for environmental policy in the past decade. Whereas the science of ecosystem dynamics suggests that it will remain difficult to define ecosystem borders and all of the natural and anthropogenic effects that influence them, the politics of ecosystem management require that a national ecosystem delineation standard be adopted. Moreover, a political framework for ecosystem management decision making must be designed in such a way as to complement the hierarchical, interrelated nature of ecosystems generally. This paper advocates that a watershed-based ecosystem delineation standard is the most politically suitable because it will be easily understood by the public and watersheds have a long history as a medium of environmental policy. The paper then proposes that the political framework for watershed-based ecosystem management must depend heavily on state and local autonomy, subject to federally prescribed standards and goals. The Coastal Zone Management Act provides a model for how a national ecosystem management policy can work within state and local watershed cultures and economies.     

Improving performance of eco-industrial parks

Abstract

Industrial Ecology hypothesises that networks of industries designed to be analogous to the structure and properties of food webs may approach a similarly sustainable and efficient state. Although ecology is the metaphor for designing Eco-Industrial Parks (EIPs), prior research has shown that EIPs are inferior in performance compared to natural ecosystems. One EIP design approach is to enlarge EIPs by combining two or more synergistic networks to create a larger, and hopefully more successful, synergistic mega-network. A quantitative analysis using structural ecosystem metrics is presented in this paper in order to test the potential of this approach. The findings indicate that merely enlarging EIPs by significant amounts may not be the best strategy for improving performance, but that special attention should be placed on the inclusion of key actors like agriculture that act like detritivores and promote more intense internal cycling.     

Managing water services in tropical regions: From land cover proxies to hydrologic fluxes

Watershed investment programs frequently use land cover as a proxy for water-based ecosystem services, an approach based on assumed relationships between land cover and hydrologic outcomes. Water flows are rarely quantified, and unanticipated results are common, suggesting land cover alone is not a reliable proxy for water services. We argue that managing key hydrologic fluxes at the site of intervention is more effective than promoting particular land-cover types. Moving beyond land cover proxies to a focus on hydrologic fluxes requires that programs (1) identify the specific water service of interest and associated hydrologic flux; (2) account for structural and ecological characteristics of the relevant land cover; and, (3) determine key mediators of the target hydrologic flux. Using examples from the tropics, we illustrate how this conceptual framework can clarify interventions with a higher probability of delivering desired water services than with land cover as a proxy.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0578-8) contains supplementary material, which is available to authorized users.