Resource managers confronted with preserving ecosystems for prairie wetland birds in fragmented landscapes require landscape studies that direct conservation efforts over broad geographic regions. We investigated the role of local and landscape factors affecting habitat suitability by integrating remotely sensed wetland and land-cover data with wetland bird habitat models. We linked habitat models with locations of easement and fee-title wetlands to evaluate spatial location and extent of protected, suitable habitat. We also simulated impacts of the loss of small wetlands on suitability of larger wetlands for mobile species that use multiple wetlands. Lastly, we evaluated the efficacy of waterfowl habitat programs in preserving suitable habitat for nongame wetland bird species to recommend strategies for maximizing regional landscape connectivity. Regional databases constructed for this study indicate that easement and fee-title tracts encompass 13.9% (1.2 million ha) of land area and protect 19.8% of the wetlands in eastern South Dakota, USA. Proportion of protected wetlands is highest for semi-permanent (32.3%), intermediate for seasonal (25.6%), and lowest for temporary wetlands (15.8%). A stratified, two-stage cluster sample was used to randomly select 834 semi-permanent and seasonal wetlands that were surveyed for birds in 1995 and 1996. Logistic analyses indicate that habitat suitability for some species (e.g., Virginia rail, pied-billed grebe) is related to local vegetation conditions within wetlands, while suitability for others (e.g., northern pintail, black tern) is related to landscape structure at larger scales. As a result, unfragmented prairie wetland landscapes (i.e., areas with wetland complexes embedded within upland grasslands) provide habitat for more species than isolated wetlands in tillage fields. Models developed from survey wetlands were used to classify habitat suitability for all semi-permanent and seasonal wetlands in eastern South Dakota. Small wetlands are critical components of the surrounding landscape that influence habitat suitability of larger wetlands. Models used to reclassify suitability of larger remaining wetlands after small wetlands (<0.5 ha) were removed indicate that species most vulnerable to loss of small wetlands are vagile species that exploit resources over broad spatial scales. Number of wetlands suitable for northern pintails, a mobile species that uses multiple wetlands within a season, decreased 20.7% when wetlands <0.5 ha were removed. Historic paradigms dictating waterfowl habitat protection efforts also have conserved habitat for nongame bird species. Modern paradigms that acknowledge the importance of small shallow wetlands to breeding waterfowl have shifted the focus of protection towards preserving habitat for species that occupy more abundant seasonal wetlands. Cessation of protection efforts would result in further fragmentation of regional wetland landscapes. We recommend that wetlands be acquired not only to consolidate suitable habitat within protected core areas but also to ensure that core areas coalesce to preserve connectivity among regional wetland landscapes.

Woody debris is an ecologically important resource in upland forests and stream ecosystems. Although much is known about invertebrate-woody debris interactions in forests and streams, little information exists for forested wetlands. In this study, invertebrates associated with woody debris in a Southeastern U. S. forested floodplain are described and factors that shape community structure are examined. Woody debris samples were collected during two wet (March 1998 and 1999) and one dry period (August 1998) from a bottomland hardwood wetland along the Coosawhatchie River, South Carolina, USA. During wet period collections, both submersed and floating woody debris were collected. Invertebrate richness, density, and arthropod standing-stock biomass were compared among sampling periods (wet and dry), between floating and submersed wood, and among woody debris decay classes. Most invertebrate richness and arthropod biomass was associated with wood collected during wet periods. However, the non-aquatic rather than aquatic arthropods were the most significant component of the overall community structure. Floating woody debris was a “hot spot” for invertebrate richness and arthropod biomass. Increased invertebrate richness was also associated with well-decayed wood. Invertebrates were classified based on temporal use of woody debris and included perennial residents, seasonal colonizers, and seasonal refugees. Overall findings suggest that woody debris is an important resource for invertebrates, and wood-associated invertebrates (especially non-aquatics) need to be considered when studying the diversity and function of forested wetlands.

After 30 years of abandonment, a block-cut peatland near Cacouna, Quebec, Canada, has naturally regenerated Sphagnum mosses on < 10% of its area, typical for these disturbed systems. Distinct hydrologic conditions were observed where Sphagnum has successfully recolonized, providing a basis for establishing thresholds that can be targeted by peatland restoration managers. Sites where Sphagnum mosses recolonized were characterized by high water table (mean−24.9±14.3 cm), soil moisture (θ) > 50%, and soil-water pressure (Ψ) >−100 mb. These hydrologic indicators were spatially organized according to the morphology of block- cut trenches, which typically include raised baulks, shallow ditches, and the convex skag (unused turf) deposits along the central axis of the trench. Topographically low areas like the shallow ditches (D) and lower parts of the skag (LS) adjacent to the ditches maintained θ and Ψ > 50% and −100 mb, respectively, for 100% of the summer period. About 83% of all Sphagnum recolonization that occurred in the study trench did so in these areas. In more raised areas like the mid- and center portion of the skag, θ and Ψ eventually fell below these thresholds, and these areas generally did not support Sphagnum, except in a few localized microtopographic depressions in the lower (downslope) end of the trench. While this lower end of the trench had all the Sphagnum species that were present in the trench, even there it was only 38% of the total area. It seems that even short periods of low Ψ may restrict Sphagnum reestablishment in an otherwise favorably wet site.

Bird species richness and individual species densities were measured in wetland complexes in 1998. These values were then related to habitat variables within the complexes and to area of wetland habitat in the surrounding landscape. The percentage of wetland area within a complex that was covered with emergent vegetation and the total area of wetland habitat in the 3 km surrounding each complex were significant predictors of species richness. A perimeter-to-area ratio was the most frequently selected variable for inclusion in species-density models, being selected for 8 of 15 models. Five species' densities were related to the percentage of the wetland area that was covered by emergent vegetation, and 4 densities were related to the area covered by weak-stemmed wet-meadow vegetation. Densities of 5 species, as well as the overall species richness, were associated with a measure of the amount of wetland habitat within a 3-km buffer surrounding the wetland complexes. This indicates that the presence and abundance of some wetland bird species may be influenced by the amount of wetland habitat nearby. Thus, programs that encourage restoration of tracts of land that contain multiple wetland basins should be emphasized to maximize benefits to the wetland bird community.

We investigated diving beetle (Dytiscidae) assemblages in twelve wetlands in an agricultural landscape in southeastern Sweden. Beetles were trapped in wetlands that varied in permanence (temporary or permanent), area (25 to 4,800 m²), age (11 to >50 yr), and shading (open to wooded surroundings). Our objective was to determine if those environmental factors are important in structuring the local assemblages of diving beetles and how the combination of different types of wetlands influence the diversity of diving beetles in a landscape. Generally, species-area relationships were weak, and shaded wetlands, both permanent and temporary, of intermediate size (240–1,100 m²) had the highest richness after a rarefaction analysis. It was not possible to discern a certain type of wetland where diversity was highest (measured by index α and Shannon-Wiener's index), although, again, intermediate sized wetlands did tend to be more diverse than others. Similarities in species compositions were highest among environmentally similar wetlands, and assemblage structure differed substantially between different types of wetlands. Results of ordination (CCA) and variance partitioning revealed that permanence and degree of shading were the most important factors in structuring assemblages. Our findings imply that high diversity of the diving beetles depends on the number of wetland types represented in a landscape. It is possible to achieve high diversity in a small area by combining permanent and temporary wetlands, as well as many age and successional stages, located in wooded and open environments.

An experimental soil microcosm system was built and soil was added and flooded to study the vertical distribution of dissolved sulfide. We compared the interstitial dissolved sulfide profiles among three experimental units by fitting them to the empirical model: sulfide = exp (b₀ b₁ / (1-depth)). The 95% confidence intervals for b₀ and b₁ of the three experimental units overlapped for the same time period for the eight different sampling times during a 95-day experiment, thus suggesting that depth-sulfide profiles were not statistically different for the three experimental units. The profile determination in this study, which used an extraction method through porous polyethylene filters, was less invasive than methods where sediment samples have been removed since it involved a minimum sediment alteration. Our system could be used to study chemical transformation in flooded soils over short intervals.

Despite a national focus on saving wetland systems in the U.S., evaluations of wetland resources and management outcomes have been limited. A fifty-state survey of wetland managers was conducted in order to collect information on (1) wetland resources, (2) management actions taken, and (3) management impact on the resources (wetlands). An overview of the general status of state knowledge of the quantity and quality of their wetland resources is presented. Results indicate that most states have a rough estimate of the resources and most have wetland conservation plans and intend to develop better databases of wetland resources. However, few states track management actions relevant to wetlands and fewer have any idea of the success or impact of past management actions. The ability to assess program effectiveness is key to implementing adaptive management frameworks. A number of lessons learned suggest a basic framework for future wetland management that includes state planning, better quantification (mapping) of wetlands, development of methods to measure wetland quality, and tracking of wetland management actions and outcomes. This framework could also be used as an outline for the development of a more adaptive approach to wetland management.

The responses of tidal marsh macroinvertebrate assemblages to the conversion of Spartina alterniflora marshes to marshes dominated by the invasive reed, Phragmites australis, are poorly understood. Changes in edaphic, vegetative, hydrologic, and detrital conditions that attend conversion to Phragmites should produce changes in the intertidal fauna. We used core sampling (7.8-cm diameter, 4-cm deep) and litter packs to compare the intertidal macroinvertebrate fauna of Phragmites marshes and adjacent remnant Spartina marshes in a brackish reach of the Mullica River (0–17 ppt salinity during the study) in southern New Jersey, USA. Detrital and above-ground vegetative biomass and water velocity were greater in Phragmites marsh; stem density, microtopographic relief, and the density of standing-water microhabitats were greater in Spartina marsh. The intertidal assemblages varied between marsh types. Total macroinvertebrate density was greater in Spartina marsh (97,000 m⁻²) than in Phragmites marsh (82,000 m⁻²). Mean taxa richness (number of taxa per core sample) was greater in Spartina marsh (12.4 taxa sample⁻¹) than in Phragmites marsh (9.4 taxa sample⁻¹) and dominance (relative abundance of the three most abundant taxa) was lower. Oligochaeta, Nematoda, and the polychaete, Manayunkia aestuarina, dominated the fauna (>75% of the total abundance) in both marsh types. Of these, oligochaetes were more abundant in Spartina marsh, and nematodes and polychaetes were slightly more abundant in Phragmites marsh. Most common subdominant taxa (100–4,000 m⁻²), including ceratopogonids, chironomids, mites, ostracods, isopods, and gastropods were more abundant in Spartina marsh. Collembolans were more abundant in Phragmites marsh; amphipods were about equally abundant in both marsh types. Invertebrate abundance and assemblage composition varied with distance from the edge of the marsh in both marsh types; overlap in assemblage composition between marsh types was greatest at the edge of the marsh, where more frequent inundation may have moderated the influence of vegetation type on the marsh fauna. For mean taxa richness and for the density of most taxa, the effect of marsh type on density exceeded the effect of season, marsh position, or a local salinity gradient. We consider the greater density of intertidal standing-water microhabitats and probably of microalgal production as important sources of faunal variation between marsh types. Fewer refugia from predators during high tide in Phragmites marsh may also contribute to variation in faunal abundance and community structure between marsh types. Detritus biomass was probably a more important source of spatial variation in the fauna of the Phragmites marsh than in Spartina marsh.

Created ponds were built as an experiment in mitigating the loss of a wetland to construction. We monitored amphibian breeding population sizes and juvenile recruitment at these “created ponds” for 8.5 years and compared the populations to those observed at the original wetland, Sun Bay (≤ 600 m from the created ponds), and at an undisturbed reference wetland, Rainbow Bay. Some amphibians continued breeding migrations to Sun Bay even after it was filled with soil. Few of the anuran colonists of the created ponds had been previously captured at Sun Bay, but many of the salamander colonists had been collected. The created ponds became permanent, whereas Sun Bay and Rainbow Bay were temporary ponds. Juveniles of two salamander species and 10 species of frogs and toads metamorphosed and emigrated from the created ponds during the study. By the final years of the study, the community structure of adult and juvenile amphibians differed among the three created ponds, as well as between these ponds and the prior amphibian community at the filled wetland and the contemporaneous community at the reference wetland. Mean size at metamorphosis was smaller at the created ponds than at the reference site for two species of frogs, whereas the opposite was true for two salamanders. We conclude that the created ponds provided partial mitigation for the loss of the natural amphibian breeding habitat. Differences between the created ponds and the natural wetlands were likely related to differences in their hydrologic regimes, size, substrates, vegetation, and surrounding terrestrial habitats and to the limited availability of colonists of some species.

Despite sedimentation being recognized as a very important process in wetlands, very little is known about its dynamics. This study analyzed sedimentation on a short-term scale in the semiarid floodplain wetland Las Tablas de Daimiel National Park (central Spain). In monthly sampling intervals during 1997 and 1998, we measured seasonal and spatial sedimentation patterns of total solids, organic and mineral matter, nitrogen, and phosphorus using sediment traps. The highest mean mass accumulation rates were obtained at the wetland-input site (135 ± 57 g m⁻² d⁻¹), but a decrease in sedimentation rates was noted with increasing distance from the inflow (49 ± 39 g m⁻² d⁻¹ in the terminal zone of the wetland). Flow and water level explained only 13% of variance in sedimentation. The sedimentation patterns presented clear seasonality, coinciding with the period of vegetation growth. There existed a marked spatial heterogeneity in sedimentation that can be attributed to differences in vegetative cover. In vegetated areas, sedimentation of solids was related with nutrient deposition coming from detritus. Sedimentation of mineral matter dominated over the organic fraction. Autochthonous material comprised a very important fraction of accumulated sediment (between 31–57% of mineral matter and 45–65% of organic matter). Sedimentation of autochthonous total phosphorus made up about 90% of total settling phosphorus. Reed (Phragmites australis) and sawgrass (Cladium mariscus) plant cover significantly explained sedimentation of organic matter in the wetland (R²= 0.78 and 0.57, respectively). The contribution of phytoplankton primary productivity to total organic carbon sedimentation was negligible and observed only at the deeper sampling stations. The autochthonous mineral matter of the settling seston may originate either from primary precipitation of endogenic calcite and/or rapid mineralization of organic matter on the sediment surface. Accretion rates were very high (1.61–3.87 cm yr⁻¹), suggesting that the wetland will silt up within the next century if present rates are maintained. Thus, sedimentation dynamics must be involved in management strategies in order to conserve important wetlands.

Ground-water seeps in the Catskill Mountains are important water sources for streams and often have different chemistry than nearby surface water. Many studies have shown correlations between water chemistry and plant species composition in wetlands, but there are no such studies in the Catskill Mountain ground-water seeps. The objective of this study was to identify the chemical and physical environmental variables that most strongly influence plant species composition in seeps. Environmental variables and plant species abundance were measured at 33 seeps. TWo-way INdicator SPecies ANalysis with analysis of variance and Canonical Correspondence Analysis showed that plant species composition is determined primarily by water depth and alkalinity/acidity complex gradients. Growing season changes in water chemistry were not shown to influence the plant community.

The invasion of prairies by woody species is a worldwide conservation concern. Fire is frequently used to inhibit this invasion. However, there is little documentation of the effect of fire in wetland prairies, which are also threatened with encroachment of woody species. The present study investigated wetland species responses to experimental burning, hand-removal of woody species, and mowing with removal of cut material. The possible ecological mechanisms responsible for individualistic responses of species, including direct mortality, ability to resprout, and release from competition are considered. We also evaluated these treatments as tools for meeting restoration objectives of reducing the abundance of woody species, reducing or preventing spread of non-native pest species, and increasing or at least maintaining native species' abundance. After two years of treatments (1994 and 1996) three patterns emerged.

1) Woody species: Burning and hand-removal caused the greatest reductions in cover of woody species. Mowing with removal of cut material, however, did not reduce the cover of woody species compared to controls. As woody plant cover decreased, plant mortality increased, indicating that treatments influenced woody plant cover at least partially through mortality.

2) Native herbaceous species: Burning significantly decreased inflorescence production of Deschampsia cespitosa, the dominant wetland prairie grass. In contrast, burning, along with mowing, significantly increased flowering of Juncus tenuis. Flowering and cover of all native graminoids combined, however, showed no significant responses to treatments. Burning and hand-removal significantly promoted the cover of native forbs as a group, with Lotus purshiana and Veronica scutellata showing the greatest increases. 3) Non-native herbaceous species: Burning and hand-removal significantly reduced the cover of non-native forbs as a group and particularly reduced the cover of Hypericum perforatum. The number of inflorescences of non- native grasses (Holcus lanatus and Anthoxanthum odoratum) increased with hand-removal and mowing. Overall, no treatment was clearly superior in fulfilling the restoration objectives. Burning was effective in reducing woody cover and did not promote abundance of non-native herbaceous species. Burning, however, reduced the flowering of the key native grass, Deschampsia cespitosa. Hand-removal of woody species was also effective at reducing woody cover and promoted the abundance of some native species, but it sometimes increased the cover of non-native herbaceous species. Because mowing with removal of cut material was ineffective in reducing woody cover and tended to promote non-native herbaceous species, this treatment is not recommended as a management tool.

This study demonstrated sampling biases of minnow traps in shallow, estuarine locations on the Eastern Shore of Virginia, USA. We exhaustively seined six shallow-water sites (including semi-permanent barrier island ponds, permanent mainland marsh ponds, tidal pools, and tidal rivulets) and compared these collection data to those obtained with minnow traps. The relative frequency of occurrence of fish species was significantly different between the two methods in all cases. Further comparison of the two techniques at ten additional sites representing a wide variety of habitat types and sizes suggested similar biases inherent to minnow traps. Specifically, minnow traps bias toward collection of a common marsh resident, the mummichog Fundulus heteroclitus, and bias against collection of several other resident species and juveniles of estuarine transient species. Minnow traps can be an effective collection technique for certain nekton species; however, specific biases inherent to the technique preclude their use as a method to accurately describe fish assemblages in shallow-water estuarine habitats.

We tested the hypothesis that large predatory fishes are major predators of amphibians and reptiles along littoral ecotones by examining the diets of 70 bowfin (Amia calva), 22 chain pickerel (Esox niger), 235 Florida gar (Lepisosteus platyrinchus), 258 largemouth bass (Micropterus salmoides), and 46 warmouth (Lepomis gulosus) collected from enhanced and non-enhanced portions of the channelized Kissimmee River, Florida, USA. Only six bowfin (9%) and four bass (2%) preyed upon herpetofauna. The diet of bowfin included peninsula newts (Notopthalmus viridescens piaropicola), greater sirens (Siren lacertina), and striped crayfish snakes (Regina alleni), whereas the diet of largemouth bass included peninsula newts, striped crayfish snakes, and stinkpot turtles (Kinosternum odoratus). No individual predator consumed more than one type of herpetofauna. The higher percentage of herpetofauna consumed by bowfin reflects this species' catholic feeding habits. Prey size was positively correlated with predator size. Eighty percent of fishes that preyed upon herpetofauna were collected from non-enhanced portions of the river, which may reflect lower abundance of preferred prey in these disturbed habitats. Overall, it does not appear that amphibians and reptiles are an important part of the piscine food web in the channelized Kissimmee River.