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1.
Riverine wetlands, which provide numerous valuable functions, are disappearing in floodplains of a channelized European river. A restoration project has been proposed by scientists to restore a former braided channel of the Rhône River by the removal of fine organic sediments in order to enhance groundwater supply. A precise and intensive prerestoration monitoring program during one year (including comparison with a reference channel) has taken into account several variables and ecological performance indicators measured at various spatial and temporal scales. Three restoration techniques were then suggested, taking into account two characteristics of ecosystem functions for increasing restoration success and self-sustainability: (1) the riparian forest as well as the shores must be preserved or disturbed as little as possible; and (2) the upstream alluvial plug must be preserved to prevent direct supply of nutrientrich water from the Rhône River. Among the three restoration options proposed, it was not possible to carry out the less ecologically disturbing one as it was considered too expensive, time consuming, and difficult to realize. A precise and intensive postrestoration monitoring program, conducted over two years, demonstrated restoration success but also unpredicted problems, such as a locally thick layer of fine organic sediment. As long as a self-sustainable state is not achieved, this monitoring should be continued. Afterwards, a less precise and less intensive long-term monitoring should enable the detection of future events that may influence ecosystem changes.  相似文献   

2.
/ Investigation of a delta marsh restoration project proposed forthe Don River in Toronto, Ontario, underlines several concerns aboutconstructed wetland projects designed for water quality improvement andaquatic habitat enhancement. The Don is a highly urbanized river that hasundergone significant physiographic modifications and continually receives acomplex mixture of conventional, metallic, and organic contaminants frommultiple point and nonpoint sources. Rather than providing permanent removalof urban contaminants, wetland processes offer a limited capacity fortemporary storage of contaminant inputs, and potential reactions may actuallyproduce more toxic and/or bioavailable forms of some chemicals. Theseprocesses tend to result in the concentration of watershed contaminants inwetland vegetation and sediments. As the restored marsh would be availablefor spawning and feeding by aquatic fauna, the potential exists for chemicalbioconcentration and biomagnification through the aquatic community.Accordingly, wetland systems are not suited to the dual purposes of waterquality improvement and aquatic habitat enhancement. Upstream controls,including source reduction of contaminant inputs, are recommended asessential components of all constructed wetland projects.KEY WORDS: Constructed wetlands; Water quality; Ecological restoration;Don River  相似文献   

3.
In the United States, the common interest often is conceived as a by-product of the pluralist, interest-group-driven democratic process. Special interests dominate in many political arenas. Consequently, we have lost the language, vocabulary, and ability to talk about the common interest. The way to reverse this trend is to develop and practice with new tools that allow us to articulate what we mean by the common interest in specific contexts. In this article, we leveraged the literature on procedural, substantive, and pragmatic decision making to illustrate how they work together to demonstrate whether and how the common interest was served in three case studies of Healthy Forests Restoration Act implementation on the Apache-Sitgreaves National Forest in Arizona. In two of the cases we found that the common interest was mostly served, while in the third case it was not. Our results raise questions about the ability of procedural criteria or substantive criteria alone to determine effectiveness in decision making. When evaluated together they provide a more complete understanding of how the common interest is or is not served.
Toddi A. SteelmanEmail:
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