26 research outputs found

    A synthesis of ecosystem management strategies for forests in the face of chronic nitrogen deposition

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    Total nitrogen (N) deposition has declined in many parts of the U.S. and Europe since the 1990s. Even so, it appears that decreased N deposition alone may be insufficient to induce recovery from the impacts of decades of elevated deposition, suggesting that management interventions may be necessary to promote recovery. Here we review the effectiveness of four remediation approaches (prescribed burning, thinning, liming, carbon addition) on three indicators of recovery from N deposition (decreased soil N availability, increased soil alkalinity, increased plant diversity), focusing on literature from the U.S. We reviewed papers indexed in the Web of Science since 1996 using specific key words, extracted data on the responses to treatment along with ancillary data, and conducted a meta-analysis using a three-level variance model structure. We found 69 publications (and 2158 responses) that focused on one of these remediation treatments in the context of N deposition, but only 29 publications (and 408 responses) reported results appropriate for our meta-analysis. We found that carbon addition was the only treatment that decreased N availability (effect size: −1.80 to −1.84 across metrics), while liming, thinning, and prescribed burning all tended to increase N availability (effect sizes: +0.4 to +1.2). Only liming had a significant positive effect on soil alkalinity (+10.5%–82.2% across metrics). Only prescribed burning and thinning affected plant diversity, but with opposing and often statistically marginal effects across metrics (i.e., increased richness, decreased Shannon or Simpson diversity). Thus, it appears that no single treatment is effective in promoting recovery from N deposition, and combinations of treatments should be explored. These conclusions are based on the limited published data available, underscoring the need for more studies in forested areas and more consistent reporting suitable for meta-analyses across studies

    Resilience indicators support valuation of estuarine ecosystem restoration under climate change

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    Economic valuation of ecological restoration most often encompasses only the most tangible ecosystem service benefits, thereby omitting many difficult‐to‐measure benefits, including those derived from enhanced reliability of ecosystem services. Because climate change is likely to impose novel ecosystem stressors, a typical approach to valuing benefits may fail to capture the contribution of ecosystem resilience to sustaining long‐term benefits. Unfortunately, we generally lack predictive probabilistic models that would enable measurement and valuation of resilience. Therefore, alternative measures are needed to complement monetary values and broaden understanding of restoration benefits. We use a case study of Chesapeake Bay restoration (total maximum daily load) to show that ecosystem service benefits that are typically monetized leave critical information gaps. To address these gaps, we review evidence for ecosystem services that can be quantified or described, including changes in harmful algal bloom risks. We further propose two integrative indicators of estuarine resilience—the extent of submerged aquatic vegetation and spatial distribution of fish. Submerged aquatic vegetation extent is indicative of qualities of ecosystems that promote positive feedbacks to water quality. Broadly distributed fish populations reduce risk by promoting diverse responses to spatially heterogeneous stresses. Our synthesis and new analyses for the Chesapeake Bay suggest that resilience metrics improve understanding of restoration benefits by demonstrating how nutrient and sediment load reductions will alleviate multiple sources of stress, thereby enhancing the system's capacity to absorb or adapt to extreme events or novel stresses

    The value of applying commercial fishers' experience to designed surveys for identifying characteristics of essential fish habitat for adult summer flounder

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    Identifying the habitat requirements of marine fish is necessary to conserve and manage their populations, but these requirements are poorly understood for many species. One method of screening for important habitat characteristics is to identify differences in habitat features between areas of high and low fish abundance. We tested the association between abundance of adult summer flounder Paralichthys dentatus and benthic habitat features at two study areas in the Middle Atlantic Bight in summer 2004. The study included trawl and remote-sensing surveys that were designed and conducted with the assistance of commercial fishers. Within each area, a local commercial fisher designated specific locations a priori as productive or unproductive for fishing. Summer flounder abundance, as measured by mean catch per area swept, was significantly greater at sites designated as productive than at sites designated as unproductive (6.5 times greater in Maryland and 4.7 times greater in Rhode Island). These results indicate that summer flounder were attracted consistently to localized habitats that must have had different characteristics than other nearby locations. Habitat variables associated with the substrate (e.g., particle size, bottom shape, and presence of sessile organisms) were measured along trawl paths using underwater video imagery. The measured variables did not explain abundance well, suggesting that microscale characteristics of the substrate did not affect summer flounder distribution. Summer flounder were most abundant at depths of 10-20 m; however, both high and low catch rates occurred in this depth range, indicating that other factors also were important. These results suggest that additional localized variables merit further investigation to determine their importance to summer flounder. This study demonstrates the importance of combining fishers' knowledge and experience with planned surveys to identify essential habitat features for fish
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