Restoration efforts and ecologically based management practices for Atlantic white cedar wetlands have recently focused on organic matter aggradation as an ecosystem function critical to this system's maintenance. The objective of this study was to evaluate environmental and substrate quality factors influencing root decomposition in naturally recovering (reference) and restored Atlantic white cedar wetlands in southeastern Virginia and northeastern North Carolina. Chamaecyparis thyoides roots were used as a standard substrate to evaluate environmental influences. Roots native to each site were used to evaluate community-level decay dynamics. Standard root mass loss was similar across all sites. Surprisingly, substantial differences in hydrology and soil organic matter among sites did not influence standard root decay. Although regression analysis detected a significant relationship between soil pH and decomposition rates, no significant relationship was found with depth to ground water. Native root decomposition rates were similar among the reference sites, but were substantially faster on the restored sites. This suggests that litter quality exerts a strong controlling influence on decomposition in Atlantic white cedar wetlands. Native root decomposition rates were correlated with lignin concentration and L:N ratios, which were higher in the roots on the reference sites due to greater proportions of woody species. Nitrogen alone did not appear to be a major regulating factor for root decomposition on our sites. Our results imply that as soon as a restored Atlantic white cedar wetland develops a closed canopy of cedar, its decomposition dynamics are likely to equilibrate with natural mature stands.

Seasonal forest pools are abundant in the northern Great Lakes forest landscape, but the range of variation in their plant communities and the relationship of this variation to multi-scale landscape features remains poorly quantified. We examined seasonal pools in forests of northern Minnesota USA with the objective of quantifying the range of variation in plant communities within and among different geomorphic and forest settings. Abundances of plant functional groups were highly variable among pools, ranging from those having abundant upland trees, sedges, and perennial forbs to those having abundant wetland sedges, grasses, and forbs. Glacial landform and ecological landtype (local forest and soil type) explained little of this variation, while physical characteristics of the pools (primarily duration of flooding) explained 36% of the variation. Understanding landscape variation in seasonal pool plant communities is important for their conservation and management. If range of variation is understood, representative examples of all variants of pool systems can be identified for conservation, and management prescriptions can be tailored to different landscape settings.

Reed canarygrass (Phalaris arundinacea L.) is an aggressive and persistent invasive species in formerly forested wetlands of the northern United States. Heavy shading reduces the dominance of reed canarygrass, so a promising long-term approach to restoration of reed canarygrass–dominated wetlands is the establishment of woody plants that will overtop and shade the grass. The first step toward developing this long-term restoration method is to determine a combination of reed canarygrass control methods and suitable trees and shrubs to provide high early survival of the native woody plants. We tested 23 tree and shrub species in five treatments to determine: 1) the woody species that have the highest survival when planted in treated stands of reed canarygrass, and 2) the pre-planting treatments that lead to the highest rates of survival. Near-monocultures of reed canarygrass were herbicided, mowed and herbicided, herbicided and plowed, or herbicided and burned. One- to three-year-old, mostly bare-rooted trees and shrubs were hand-planted into these treatments and into untreated control plots at three sites, and over two growing seasons. Fall herbicide followed by spring plowing provided the highest survival for the majority of species planted. However, all experimental treatments (controlling reed canarygrass with a single herbicide application) provided reasonably high survival of the 10 most successful woody species. Those pre-planting treatments and study sites that developed the greatest herbaceous species diversity after treatment had the highest tree and shrub survival. The early establishment success we found using these methods is encouraging for development of a technique for restoring swamp forest in degraded reed canarygrass–dominated wetlands.

Cobalt is a minor contaminant in wetlands that has been linked to accumulation by Nyssa species for many years, though the evidence is largely anecdotal. We examined cobalt uptake characteristics from cobalt-enriched potting soil by Nyssa aquatica (water tupelo), N. sylvatica var. biflora (swamp tupelo), and Taxodium distichum (baldcypress), codominant canopy species of wetland forests of the southeastern United States. Seedlings were grown in 10 l pots for two growing seasons. Cobalt additions (up to 100 mg/pot) did not affect biomass production of leaves, stems, or roots of the three species. Height was significantly different among treatments within a species, but no treatment was different from the control treatment with no added cobalt. Leaf cobalt concentrations were greater in N. sylvatica var. biflora than N. aquatica during the first year, but similar during the second year. Cobalt concentrations declined from the first to second years for T. distichum leaves. In the 100 mg/pot treatment, leaf cobalt concentrations of both Nyssa species during the second year were 150 times greater than that of T. distichum. Elevated cobalt uptake by Nyssa species is apparently a function of special mechanisms of the genera and not a habitat characteristic.

To improve our ability to predict how different wetland soils cycle nutrients, it is necessary to gain an understanding of N and P net mineralization rates. Since information on mineralization rates in southeast Alaska is limited, this study will improve our ability to predict how different wetlands affect soil nutrient processing. Net N and P mineralization rates were measured both in situ and via lab incubations to evaluate both actual and potential mineralization rates in three wetland types: bogs; forested wetlands; and riparian wetlands. Soil pH was an important controlling variable for both net N and P mineralization rates and soil phosphorus content significantly influenced net P mineralization rates. In situ net mineralization rates ranged from 410–1,710 µg N kg soil⁻¹ day⁻¹ for N and from 2–27 µg P kg soil⁻¹ day⁻¹ for P after 56 days. Lab incubations revealed mineralization potentials were 2–3 times greater than in situ rates. Net N and P mineralization potentials were greatest in the riparian wetlands and were significantly different from the bogs and forested wetlands. In contrast, the bogs mineralized a greater proportion of the total N and P soil pool (µg nutrient mineralized per gram nutrient) and indicates greater internal nutrient cycling within bogs. These results suggest that different wetland types of southeast Alaska process N and P differently and these wetland types should be evaluated separately in future evaluations of wetland ecosystem function.

The invasion of U.S. east coast salt marshes by common reed (Phragmites australis) and the efforts to remove it and restore marshes to their natural vegetation (Spartina spp.) can directly impact mummichog (Fundulus heteroclitus) as this abundant species is critically linked to marsh habitat. We estimated population density, growth, and biomass to determine production of mummichog in treated Phragmites (“Treated,” now dominated by Spartina), untreated Phragmites, and naturally occurring Spartina habitats in Delaware Bay using throw traps for small fish (mean  =  24.1 mm standard length or SL, 95% CI  =  10–38) and tag/recapture for large fish (mean  =  36.5 mm SL, 95% CI  =  18–64). Mean population density of small fish on the marsh surface was significantly higher in the Spartina (20.2 fish m⁻²) and Treated (14.1 fish m⁻²) habitats than in the Phragmites (0 fish m⁻²) habitat. Population density of large fish was similar among all three habitats (mean  =  0.9–1.7 fish m⁻²). Mean absolute growth rates of large fish were significantly higher in the Spartina (0.24 mm d⁻¹) and Treated (0.24 mm d⁻¹) habitats than in the Phragmites (0.13 mm d⁻¹) habitat. Mean monthly mummichog production during June to September varied among habitats with Spartina highest (1.22 g dw m⁻² mo⁻¹), Treated intermediate (0.51 g dw m⁻² mo⁻¹), and Phragmites lowest (0.07 g dw m⁻² mo⁻¹). Small fish were the largest contributor to the production estimates in Spartina and Treated habitats. The Phragmites habitat had little or no standing water at low tide (i.e., optimal habitat for small fish was lacking), and thus, it had the lowest production for mummichog. These results also indicated that Treated marshes were more similar to Spartina than to Phragmites habitat; therefore, it appears that habitat quality and mummichog production can be increased with restoration.

Forested wetlands are important ecosystems valued for their indigenous plant communities, spatial heterogeneity, wildlife habitat, water quality, and timber resources. When harvested for timber, plant composition in these wetlands may change due to alteration in microsite habitats. Harvest severity also may affect plant composition. In this study, a mineral conifer wetland was subjected to whole-tree harvesting followed by installing different site preparations (bedding, trenching, draining). The original wetland overstory was Picea mariana, Larix laricina, and Pinus banksiana, with groundcover dominated by Sphagnum russowii. Eleven to twelve years after harvest, we assessed responses of vascular and non-vascular plants to created microtopographies (pits, side slopes, mounds) to determine whether harvest severity affected species richness, diversity, and relative cover of plant communities. For all the microtopography positions, the more severe harvest treatments (drained, cut, trenched) had the highest plant richness but the lowest diversity values. Richness and relative cover of Sphagnum species were highest in reference areas and much lower in the most severe harvest treatments (drained, cut, trenched). In contrast, graminoid and, to a lesser extent, herbaceous and woody plants increased in richness and cover after harvest.

Use of citizen-scientists to collect data on natural resources is gaining credibility globally and is now considered a valuable tool in the conservation tool box. We conducted town-wide vernal pool inventories using citizen-scientists in four New England towns (USA) using voluntary best development practices (BDPs) for vernal pools. We tested the efficacy of using citizen-scientists to collect field data on vernal pools using published BDP guidelines. Steps included pool mapping and inventory, training of citizen-scientists, vernal pool field assessments, and guiding town development of local conservation strategies using data provided by the project. Potential vernal pools were remotely identified and photointerpreted. Partnerships among the University of Maine, the towns, and non-governmental organizations were forged to implement the project in spring 2003. Local coordinators in each town recruited volunteer citizen-scientists to conduct ground assessments. Volunteer training sessions were held prior to and during the field season. Fifty-two citizen-scientists surveyed and assessed 262 vernal pools. Quality control tests in the field confirmed that citizen-scientist data on amphibian egg mass counts were not significantly different from data gathered by biologists. Each pool was given a conservation priority rating based on the BDP assessment. Data were entered into a Geographic Information System database and delivered to each town. All towns initiated conservation plans and are developing conservation mechanisms to protect pools recognized as having conservation priority. Town strategies ranged from amending existing ordinances to improve wetland protection to incorporation of vernal pool resources into larger biodiversity mapping and planning projects. These four case studies illustrate that vernal pool conservation initiatives can be developed in local communities using the skills of trained citizen-scientists to collect accurate data. Communities are then better able to incorporate pool conservation strategies into the local planning and regulatory processes.

Establishing criteria for protecting or improving wetland condition has often focused on physical and chemical factors, which can paint an incomplete picture of wetland quality. To protect the biological integrity of aquatic environments, identifying criteria based on biological responses to pollution is essential. We hypothesize that assessment of multiple taxonomic groups and response thresholds will provide statistically defensible effects-based methods to define reference condition and establish biological criteria. We used regression tree analysis to identify non-linear biological responses of three taxonomic groups (macrophytes, epiphytic diatoms, and plant-associated zooplankton) collected from 36 depressional wetlands in the Muskegon River watershed (Michigan, USA). Multi-metric biotic indices were developed for all three taxonomic groups and these indices were combined to reveal biologically relevant thresholds along a gradient of human disturbance. We found these three taxonomic groups responded at similar levels of impairment and could be used to classify wetlands into three groups: reference sites representing the highest quality wetlands in the landscape; slightly altered sites where the most sensitive organisms responded (sensitive plants, diatoms); and degraded sites where extensive changes in community structure occurred, which may reflect a shift to an alternate state. For the Muskegon River watershed, in particular, this analysis allowed us to identify sites in need of restoration, including approximately one-third of the depressional wetlands in the watershed. This study outlines a method for identifying criteria that could be used for regulatory purposes. In particular, we recommend the use of community-level metrics in identifying broad-based changes in community composition that may represent shifts to alternate states, as well as the use of sensitive indicators, such as the occurrence of sensitive plant and diatom taxa.

Variation in hydrologic regimes in subtropical lakes and wetlands strongly influences biodiversity and value to human users. Lake Okeechobee, Florida, has a 450-km² littoral landscape that supports a diverse assemblage of aquatic vegetation that provides critical habitat for fish and wildlife. Water level is one of the primary factors affecting the composition of aquatic vegetation and its associated faunal assemblages at Lake Okeechobee. We summarized published literature regarding the effects of water-level variation on subtropical wetland and littoral plants, as well as the fish and other biota supported by those plant communities, with an emphasis on shallow lakes and wetlands occurring at latitudes generally similar to Lake Okeechobee. The objective of this study was to enhance the information base that supports the CERP (Comprehensive Everglades Restoration Plan) hydrologic performance goals for this large lake ecosystem. Our results demonstrate that high water/prolonged flooding at lake stages exceeding 5.1 m msl (mean sea level) will cause substantial loss of aquatic and wetland plants at Lake Okeechobee, which will negatively impact fish and wildlife populations. Conversely, very low water (< 3.7 m msl) on a regular basis may favor expansion of native plants but also torpedograss, Panicum repens (a non-native), which would require more intensive control programs. If Okeechobee lake stage varies between 3.7 and 4.6 m msl in most years, littoral and near-shore zones can be expected to develop diverse and widespread stands of emergent and submerged aquatic vegetation. If these changes occur, we predict that largemouth bass (Micropterus salmoides) and other fish species, alligators (Alligator mississippiensis), wading birds, and snail kites (Rostrhamus sociabilis) would all positively respond due to enhanced habitat structure and food resources.

Aquatic macroinvertebrates of the Okefenokee Swamp have been largely overlooked despite their ecological importance and value as water quality indicators. In a two-year study we analyzed taxon richness and abundances of individual macroinvertebrate taxa in the Okefenokee Swamp to assess temporal variation among seasons and spatial variation among five plant community habitats (marsh prairies, cypress forest, scrub-shrub thickets, deepwater lakes, and boat trails) and across six areas of the Okefenokee. Chironomid and ceratopogonid midges and water mites numerically dominated the macroinvertebrate community, and chironomids, dytiscid beetles, and libellulid dragonflies had the greatest generic richness. Multivariate analysis of macroinvertebrate community structure did not show clear patterns among seasons, habitats, or areas. Furthermore, few individual taxa had either spatial or temporal variation in abundance. Wetland macroinvertebrate communities were relatively homogenous across the Okefenokee Swamp possibly because conditions important to these organisms did not vary dramatically among habitats or seasons. Alternatively, most resident taxa might be ecological generalists able to exploit a broad range of conditions.

We assessed changes in vegetative structure of 49 impoundments at Moosehorn National Wildlife Refuge (MNWR), Maine, USA, between the periods 1984–1985 to 2002 with a multivariate, adaptive approach that may be useful in a variety of wetland and other habitat management situations. We used Mahalanobis Distance (MD) analysis to classify the refuge's wetlands as poor or good waterbird habitat based on five variables: percent emergent vegetation, percent shrub, percent open water, relative richness of vegetative types, and an interspersion juxtaposition index that measures adjacency of vegetation patches. Mahalanobis Distance is a multivariate statistic that examines whether a particular data point is an outlier or a member of a data cluster while accounting for correlations among inputs. For each wetland, we used MD analysis to quantify a distance from a reference condition defined a priori by habitat conditions measured in MNWR wetlands used by waterbirds. Twenty-five wetlands declined in quality between the two periods, whereas 23 wetlands improved. We identified specific wetland characteristics that may be modified to improve habitat conditions for waterbirds. The MD analysis seems ideal for instituting an adaptive wetland management approach because metrics can be easily added or removed, ranges of target habitat conditions can be defined by field-collected data, and the analysis can identify priorities for single or multiple management objectives.

Estimating the distribution of amphibians in terrestrial habitats surrounding wetlands is essential for determining how much habitat is required to maintain viable amphibian populations and how much habitat may be allocated to other land use practices. We apply univariate kernel estimation in a new manner to determine the distribution of amphibians during the non-breeding season. We summarized data from 13 radio telemetry studies that reported net maximum distance traveled from the breeding site for each individual (n  =  404 individuals), and calculated a univariate kernel density estimate for all data combined. Kernel density estimation provides a function for the probability of an amphibian being present at a given distance from the breeding site and bootstrap methods allow for error estimates of isopleth values. Amphibians generally occurred at a short distance from the wetland (50% isopleth was at 93 m) and declined at greater distances (95% isopleth was at 664 m); however, use of habitat immediately adjacent (e.g., < 30 m) to the breeding site was lower than the peak for all species. The shape of the distribution was consistent for frogs and salamanders; however, the 95% kernel isopleth for the salamander estimate (245 m) was less than half the distance of the frog estimate (703 m), indicating that frogs distributed themselves at much greater distances from the breeding site than salamanders. Kernel estimates for the two western species, Rana luteiventris> and Bufo boreas>, did not peak near the breeding site as in the other species, suggesting that non-breeding habitat for these species is not located near breeding sites. We were unable to detect a statistical difference between sexes, but females tend to use habitat at greater distances from the wetland than males. Our results revealed that amphibians are not uniformly distributed in terrestrial habitats surrounding wetlands.

Temporary wetlands are an ecologically and economically important habitat in South Africa. They harbor large branchiopods, known to be flagship species of nonpermanent aquatic habitats, and sensitive to land use changes. In this study we review the current status of large branchiopods in the Western Cape, a South African province subject to increasing agriculture and urbanization. We studied the species diversity and distribution of large branchiopods by sampling 58 temporary wetlands in an area covering about 30% of the Western Cape. Information obtained from field samples was supplemented by incubating resting egg banks from the sampled wetlands. Our data were compared with all known distribution records for large branchiopods in the target region. Based on this combined information, the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List category was assessed for each species. Four of the eight large branchiopod species known to occur in the sampling area were collected. Of all wetlands sampled, 40% harbored large branchiopods. Most anostracan populations were small, and species co-occurred in only one wetland. From the entire Western Cape, 14 species have been recorded in the past. Two of these are already included in the IUCN Red List. Insufficient data are available to determine the IUCN Red Data Category of six other species. A large variation in the telsonic appendages of S. dendyi was found across the studied area. In view of possible ongoing speciation and subsequent radiation, individual populations need protection. Since little information is available, it is difficult to evaluate recent changes in the conservation status of large branchiopods. Their populations are currently very low and have probably diminished in the last few decades. More knowledge about the functioning of temporary systems is needed to manage these vulnerable habitats and conserve their threatened species.

Hydrologic patterns and soil characteristics were investigated at three high-elevation wetlands in southeastern Kentucky, Martins Fork, Kentenia, and Four Level. Despite below-normal precipitation, water tables at all sites remained within 35 cm of the surface and fluctuated seasonally with peak heights during early spring. Seasonal precipitation contributed substantially to Martins Fork hydrology, while ground water was the primary hydrologic source for Kentenia and Four Level. Vertical hydraulic gradients varied among the sites. Martins Fork was distinguished by strong seasonal downwelling, while Kentenia and Four Level exhibited upwelling and downwelling patterns. All sites exhibited prominent soil hydromorphic features immediately below the surface horizon, moderate organic carbon content (< 6.5%), and a pH range between 4.4 and 6.2 according to the buffering capacities of local lithologies. The sites were dominated by sandy loam texture and siliceous mineralogy, reflecting the influence of sandstone parent materials prevalent in the area. Radiocarbon dating established that soil surface layers (≤ 30 cm) dated less than 250 years B.P., while soil horizons at 100-cm depths varied from 770–1,870 years B.P. Mean C sequestration rates ranged from 0.025 kg C m⁻² at Four Level to 0.043 kg C m⁻² for Martins Fork and Kentenia, with C accumulation in the upper 100 cm in the range of 19.5–36.7 kg C m⁻². Each wetland exhibited distinctive hydrologic and soil properties derived from geologic, geomorphic, and vegetative influences.

Restoration of disturbed wetland systems is an important component of wetland mitigation, yet uncertainty remains about how hydrologic processes affect biologic processes and wetlands patterns. To design more effective restoration strategies and re-establish native plant communities in disturbed wetlands, it is imperative to understand undisturbed systems. A site within Cherokee Marsh located in Madison, Wisconsin, USA, contains a relatively undisturbed area of wetland consisting of plant communities common within the prairie landscape including a fen, sedge meadow, and shallow marsh. These distinct communities are found within an area of minimal topographic relief, yet transitions from one community to the next occur over short distances. This study sought to characterize the geologic, hydrologic, and chemical gradients associated with these shifts in vegetation to gain insight into the factors controlling the spatial differences in dominant plant species, which could be critical for restoration success. Vegetation analyses revealed a transition of dominant sedge species, which appeared to correspond to changes in hydrology from a ground-water dominated to a surface-water dominated system (as determined by water isotopes). Along the same vegetation transect, subsurface coring results show a heterogeneous composition of peat and till with lateral and vertical variations in stratigraphy, which relates to variability in ground-water discharge as evidenced by hydroperiods and stable isotope composition. Applications of this type of approach throughout the glaciated terrains of the midwestern and northeastern United States and Canada can improve future wetland restoration and management.

Although the introduced zebra mussel, Dreissena polymorpha, has eliminated most native unionid populations within the lower Great Lakes, some recent surveys have found diverse unionid communities in several Lake Erie coastal wetlands. In 2004, we tested whether fish predators reduced zebra mussels on Quadrula quadrula (Unionidae) in a Lake Erie coastal wetland. In June, we placed unionids and colonization plates in small-mesh exclosures (2.5-cm × 2.5-cm mesh), large-mesh exclosures (5-cm × 10-cm mesh), and open exclosures (2.5-cm × 2.5-cm mesh with two 40-cm × 40-cm openings). Zebra mussels and other benthic molluscs were sampled in October, and zebra mussel numbers on Q. quadrula outside exclosures were significantly higher in October than in June. Densities of zebra mussels on Q. quadrula and colonization plates were much higher in small-mesh and large-mesh treatments that excluded large fish than open treatments. Mean (±1 SE) densities of zebra mussels/unionid were also higher inside (1041 ± 103) than outside (6.9 ± 1.5) exclosures in October. These results indicate that large-bodied molluscivores (e.g., common carp, freshwater drum, channel catfish) can limit zebra mussel numbers in coastal wetlands. Densities of other molluscs (Sphaeriidae, Corbiculidae, Gastropoda, and Unionidae) were not different in sediments of exclosures and uncaged areas, suggesting that fish can have a greater impact on numbers of attached zebra mussels than benthic molluscs.