"Wetlands"

Jones, Phillip D.;Hanberry, Brice B.;Demarais, Stephen

doi: 10.1007/s13157-010-0060-8pmid: N/A

Abstract Forest certification programs require program participants to manage for biodiversity using science-based information. Management at the interface of retained wetland features and plantations provides opportunities to enhance wildlife diversity on commercial pine forest lands. We review the scientific literature to document how wildlife in managed pine forests might benefit from retention of isolated wetlands and riparian zones, and potential effects of forest management on conservation of wetland-associated wildlife on managed pine forests of the southern USA. We suggest research goals and methodologies to address information gaps critical to improved management. Many available studies lacked inferential power, and most depended on measures of diversity, richness, or abundance rather than community similarity or demographic measures of fitness. Observational studies have yielded potential hypotheses that should be tested with manipulative experiments. Demographic measures of fitness should replace potentially misleading measures of abundance or density, and diversity measures supplemented with comparisons of community similarity. Researchers should institute long-term studies to account for temporal variability. Multi-scale analyses would help determine appropriate management scale for isolated wetlands and the utility of riparian areas and associated streamside management zones as dispersal corridors. Landscape-level models would facilitate long-term planning and provide a framework for adaptive management.

Jurado, Gustavo Becerra;Johnson, James;Feeley, Hugh;Harrington, Rory;Kelly-Quinn, Mary

doi: 10.1007/s13157-010-0040-zpmid: N/A

Abstract Integrated Constructed Wetlands (ICWs) constitute an alternative option for the treatment of agricultural wastewater in Ireland. These surface flow systems are formed by interconnected ponds and have the capacity to fit into the landscape and provide habitat for a wide range of biota, including macroinvertebrates that have enormous potential for biodiversity enhancement. For these reasons, five ICW systems were studied. In addition, five natural ponds were investigated to account for the potential of ICW ponds to mimic natural conditions. Nine river sites were also investigated to allow for an evaluation of the catchment biodiversity contribution of the ICW systems. The present study revealed that the last ponds in the chain of these ICW systems are capable of supporting a similar number of taxa as natural ponds. Furthermore, the contribution of the last ponds to the macroinvertebrate diversity at the catchment level was high. ICWs seem to integrate their effluent management and purifying properties with that of biodiversity enhancement and landscape fit. This is the first study to investigate the potential of constructed interconnected ponds, used for wastewater treatment, to enhance biodiversity in agricultural landscapes.

Keeland, Bobby D.;Draugelis-Dale, Rassa O.;McCoy, John W.

doi: 10.1007/s13157-010-0062-6pmid: N/A

Abstract Green-Tree Reservoirs (GTR) are bottomland hardwood forests that are flooded during late fall and winter to provide waterfowl habitat. Early reports suggested that increased moisture improved tree growth and mast production; however, recent reports showed reduced vigor and growth. This study examines the effects of 20 years of GTR management practices in the Felsenthal National Wildlife Refuge, Crossett, Arkansas. Tree species composition, size characteristics, and vigor classes were measured in 1990, 1995, 2001, and 2006. The overall annual tree mortality rate was 2.6%, with high elevations at 1.7% and low elevations at 3.1%. Annual mortality rates exceeded 3% for willow oak (Quercus phellos) and water hickory (Carya aquatica), while rates for Nuttall oak (Q. texana), overcup oak (Q. lyrata), and sweetgum (Liquidambar styraciflua.) were lower at 2.8, 2.4, and 1.5%, respectively. Tree health (vigor) has degraded substantially for over 60% of trees initially rated in good or fair condition. Statistical probit models were generated to predict short-term (5 years) and long-term (15 years) vigor degradation. Low numbers of saplings and little advanced regeneration indicated lack of tree replacement, suggesting that inundation strategies of the GTR management may have long-term impacts on forest structure and composition in the southeastern United States.

Milzow, Christian;Tshekiso, Otlaathusa;Kgotlhang, Lesego;Kinzelbach, Wolfgang

doi: 10.1007/s13157-010-0042-xpmid: N/A

Abstract The Okavango Delta of northern Botswana comprises large wetlands that spread over an alluvial fan of 150 km in length. Only part of the fan is covered with wetlands but the repeated shifting of the zones prone to inundation has led to a regular distribution of sediments and eventually to the formation of a smooth fan surface. We conducted repeated solute and bedload transport measurements at the inlet and within the wetlands proper to quantify sediment input and channel aggradation rates. The relationship between flow velocity and bedload transport was used to simulate channel erosion and aggradation, and a bedload transport component was built into a numerical hydrological model of the Okavango Delta. The model was used to assess the impact of a hypothetical dam in the upstream of the wetlands on channel bed elevations and the distribution of flooded areas. Our results suggest that the contribution of solute inputs to the overall sediment accumulation of the fan has been overestimated relative to bedload inputs. The numerical simulations reveal that a dam would have an impact on channel elevations only in its immediate downstream, but an impact on the distribution of flooding would be felt over the entire wetland system.

Bunch, Aaron J.;Allen, Micheal S.;Gwinn, Daniel C.

doi: 10.1007/s13157-010-0051-9pmid: N/A

Abstract Many aquatic systems worldwide have experienced significant changes in littoral macrophyte communities from altered hydrology in the form of water controls structures (e.g., dams). Water level stabilization for flood control can cause persistent occurrence of dense stands of emergent macrophytes, which can affect the physicochemical environment for fishes. We evaluated dissolved oxygen (DO) concentrations in five emergent macrophyte species (cattail Typha spp., pickerelweed Pontedaria cordata, smartweed Polygonum spp., torpedograss Panicum repens, and water primrose Ludwigia spp.) at three levels of macrophyte coverage (i.e., 50–64, 65–79, and 80–95%) at Lake Istokpoga, Florida during July–August (summer) and October–November (fall) 2007. Dissolved oxygen exhibited substantial spatial and temporal variability at small scales (i.e., meters and hours), with the lowest DO and highest probability of hypoxia occurring in smartweed and water primrose habitats relative to other macrophyte types. The probability of hypoxia increased with macrophyte coverage for all macrophyte species tested. Dissolved oxygen was influenced by the structural differences (e.g., stem density and size) and spatial orientation (e.g., proximity to open water) associated with the individual macrophyte habitats. Restoration efforts that create open water pathways and maximize edge areas might improve DO concentrations and habitat quality and quantity for freshwater fishes.

Kauffman-Axelrod, Jennifer L.;Steinberg, Steven J.

doi: 10.1007/s13157-010-0061-7pmid: N/A

Abstract Recent geographic information system (GIS) mapping of Oregon’s tidal wetlands identified over 2,000 potential restoration areas. Given the large number of restoration opportunities, we developed automated GIS tools to assist resource managers in prioritizing areas with less hydrologic alteration and more favorable landscape scale metrics. The Coos estuary and watershed was used as an example of a regional application. We developed nine GIS tools using scripting techniques to prioritize among 530 potential restoration sites using widely available state-wide datasets. Parameters evaluated were limited to factors affecting a site’s hydroperiod at multiple scales and reflecting consideration of ecological principles. Tabular model output was used to prioritize potential restoration sites. Prioritization ranks were calculated using a three-tier weighted summation designated by Coos estuary restoration practitioners. Standardized ranks ranged from 0.479–1.000 on a zero to one scale. Higher ranks indicate more favorable landscape scale metrics and less cumulative hydrologic alteration. Model output, standardized parameter scores, and prioritized rankings of potential restoration sites were stored in a Microsoft Access database coupled with a geodatabase containing spatial geometry. These automated tools present repeatable and flexible methods for evaluation and prioritization of a large number potential restoration sites in Oregon.

Wasson, Kerstin

doi: 10.1007/s13157-010-0056-4pmid: N/A

Abstract The goal of this investigation was to inform restoration strategies by determining which factors are most important in limiting Olympia oyster (Ostrea lurida) distribution and abundance at a Pacific coast estuary, Elkhorn Slough in central California, where Olympia oysters are currently extremely rare but were formerly abundant. An array of mensurative experiments and correlative analyses were used to examine the role of potential limiting factors. Absence of oysters was associated with symptoms of eutrophication, including elevated nutrient concentrations and turbidity. Oysters were also absent from all sites where water control structures resulted in minimal tidal exchange. Predation and competition did not appear to play a major role in surveyed oyster populations above Mean Lower Low Water but at lower elevations oysters were heavily fouled by non-native species. In most sites oysters were found only on large artificial substrates; survival on small natural hard substrates was apparently precluded by burial by fine sediments. Restoring more natural ecosystem processes by reducing nutrient and sediment inputs, increasing tidal exchange to areas behind water control structures, and preventing establishment of new non-native species would benefit Olympia oysters as well as support broader ecosystem-based management goals.

Woodcock, Thomas S.;Monaghan, Megan C.;Alexander, Karen E.

doi: 10.1007/s13157-010-0057-3pmid: N/A

Abstract Stormwater ponds (SWPs) are wetlands created or engineered for the purpose of collecting and controlling urban runoff, sediments, and toxins prior to discharging into other surface and/or ground waters. As wetlands face increasing pressure from development, many SWPs are also considered by planners as a valid solution to the problem of wetland habitat loss. This study compares water chemistry, organic matter dynamics, and macroinvertebrate community structure, biomass, and secondary productivity in a sample of SWPs with nearby reference wetlands of natural origin. Although total secondary productivity of invertebrates was greater in SWPs, significant differences were observed in water chemistry, invertebrate community structure, invertebrate biomass turnover, and organic matter dynamics that suggest that the SWPs were not comparable to the reference wetlands from the point of view of ecosystem function and conservation. Furthermore, improvement in the function of SWPs in pollutant control might be achieved by improving their function in conservation, most notably by considering the role of organic matter inputs from adjacent terrestrial areas in the planning.

Stralberg, Diana;Herzog, Mark P.;Nur, Nadav;Tuxen, Karin A.;Kelly, Maggi

doi: 10.1007/s13157-010-0052-8pmid: N/A

Abstract Tidal marsh monitoring and restoration can benefit from the union of fine-scale remote sensing products and field-based survey data via spatial predictive models. As part of an interdisciplinary wetland monitoring project in San Francisco Bay, we developed a suite of 1-m pixel-level spatial metrics describing patterns in marsh vegetation and geomorphology for six sites across a large salinity gradient. These metrics, based on multi-spectral aerial imagery and derived vegetation maps, provided a basis for fine-scale spatial modeling of avian habitat potential. Using common yellowthroat (Geothlypis trichas), song sparrow (Melospiza melodia), and black rail (Laterallus jamaicensis) abundance data, we developed statistical models with relatively high explanatory power. In each case, models were improved by including vegetation-map variables, but variables directly extracted from aerial imagery were more reliable indicators of avian abundance. Although results varied by species, our models achieved reasonable within-site predictive success. When predicting to sites not used in the training set, however, validation results were inconsistent and often poor, suggesting that these models should be used with caution outside of the original study sites. As remotely sensed data become more readily available, our methods may be applied to a diverse range of sites, resulting in improved model generality and applicability.

Laidig, Kim J.;Zampella, Robert A.;Brown, Allison M.;Procopio, Nicholas A.

doi: 10.1007/s13157-010-0063-5pmid: N/A

Abstract We developed vegetation models that, when linked to groundwater-hydrology models and landscape-level applications, can be used to predict the potential effect of groundwater-level declines on the distribution of wetland-forest communities, individual wetland species, and wetland-indicator groups. An upland-to-wetland vegetation gradient, comprising 201 forest plots located in five different study basins and classified as either upland pine-oak, pitch pine lowland, pine-hardwood lowland, hardwood swamp, or cedar swamp, paralleled variations in water-level. Water levels, woody-species composition, the percentage of wetland- and upland-indicator species, and soil properties varied among the five vegetation types. Because of the functional relationship of hydrology with its correlated soil variables, hydrology represented a good proxy for the complex hydrologic-edaphic gradient associated with the upland-to-wetland vegetation gradient. Two types of vegetation models were developed to predict potential changes in vegetation associated with water-level declines. Logistic regression models predicted the probability of encountering the different vegetation types and 29 community-indicator species in relation to water level. Simple regression models predicted the relative abundance and richness of wetland-and upland-indicator species as a function of water level.