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Austin, TX, United States

Robertson M.,University of Wisconsin - Madison | BenDor T.K.,University of North Carolina at Chapel Hill | Lave R.,Indiana University Bloomington | Riggsbee A.,RiverBank Ecosystems Inc. | And 2 more authors.
Frontiers in Ecology and the Environment

Ecosystem service markets are increasingly used as a policy solution to environmental problems ranging from endangered species to climate change. Such markets trade in ecosystem credits created at restoration sites where conservation projects are designed and built to compensate for regulated environmental impacts. "Credit stacking" occurs when multiple, spatially overlapping credits representing different ecosystem services are sold separately to compensate for different impacts. Discussion of stacking has grown rapidly over the past three years, and it will generate increasing interest given the growing multibillion-dollar international market in carbon, habitat, and water-quality credits. Because ecosystem functions at compensation sites are interdependent and integrated, stacking may result in net environmental losses. Unless stacked compensation sites and impact sites are treated symmetrically in the accounting of environmental gains and losses, stacking may also cause environmental gains at compensation sites to be more fully accounted for than losses at impact sites. Stacking should be used with caution until science-based methods, which can account for the ecological relationships between distinct ecosystem credits present at a conservation site, are developed and deployed. © The Ecological Society of America. Source

Bendor T.K.,University of North Carolina at Chapel Hill | Riggsbee J.A.,RiverBank Ecosystems Inc. | Doyle M.,Duke University
Environmental Science and Technology

Market-based environmental regulations (e.g., cap and trade, "payments for ecosystem services") are increasingly common. However, few detailed studies of operating ecosystem markets have lent understanding to how such policies affect incentive structures for improving environmental quality. The largest U.S. market stems from the Clean Water Act provisions requiring ecosystem restoration to offset aquatic ecosystems damaged during development. We describe and test how variations in the rules governing this ecosystem market shift risk between regulators and entrepreneurs to promote ecological restoration. We analyze extensive national scale data to assess how two critical aspects of market structure - (a) the geographic scale of markets and (b) policies dictating the release of credits - affect the willingness of entrepreneurs to enter specific markets and produce credits. We find no discernible relationship between policies attempting to ease market entry and either the number of individual producers or total credits produced. Rather, market entry is primarily related to regional geography (the prevalence of aquatic ecosystems) and regional economic growth. Any improvements to policies governing ecosystem markets require explicit evaluation of the interplay between policy and risk elements affecting both regulators and entrepreneurial credit providers. Our findings extend to emerging, regulated ecosystem markets, including proposed carbon offset mechanisms, biodiversity banking, and water quality trading programs. © 2011 American Chemical Society. Source

Riggsbee J.A.,University of North Carolina at Chapel Hill | Riggsbee J.A.,RiverBank Ecosystems Inc. | Wetzel R.,University of North Carolina at Chapel Hill | Doyle M.W.,University of North Carolina at Chapel Hill
River Research and Applications

Dam removal has emerged as a critical issue in water resources engineering and management. Of particular concern in many regions of the USA is the effect of dam removal on downstream water quality and potential methods of decreasing sediment and nutrient loading to downstream reaches. Rapid revegetation of reservoir sediments has been suggested as a means of reducing the impact of dam removal, although little data exist about the role of vegetation in controlling the downstream release of sediment or nutrients. This study investigated an impounded riverine wetland complex on the Little River, North Carolina, before and after the removal of a low-head dam. We quantified the leaching of interstitial nitrogen (N) and phosphorus (P) to the adjacent river channel during reservoir dewatering and, through experimental manipulations, isolated the difference between physical (soil) and biological (plant) controls on N and P leaching from dewatering impoundment sediments. We found that the rate and the quantity of N and P leaching from impounded dewatering sediment are predominately controlled by sediment porosity and specific yield. Although vegetation controls on N and P leaching were statistically significant during the first growing season following dam removal, vegetation is likely to be more important as a long-term control on sediment and nutrient loads. Our results suggest that the initial release of N and P from a dewatered reservoir will be difficult to control but that vegetation may play an important long-term role. © 2011 John Wiley & Sons, Ltd. Source

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