Vegetation structure is an integral component of avian habitat selection. Therefore, structure changes caused by management practices can influence avian communities. The salt marshes of the pampas region of Argentina have experienced an increase in fire use as a management tool to improve cattle forage and to avoid accidental fires. A spring burn of 200 ha of salt marsh in Mar Chiquita Biosphere Reserve, Argentina, in September 1995, allowed us to compare the response of birds associated with two vegetation communities, one dominated by Spartina densiflora (Spartina marsh) and another dominated by Juncus acutus (Juncus marsh) from one month to one year post-burn. We recorded changes in plant species composition and vegetation structure (height and cover) at 40 days after the burn and every season for the subsequent year. Fire reduced total cover of both plant communities. Juncus marsh recovered pre-burn structure and bird community by one year post-fire. However, Spartina marsh recovery was incomplete in that period. Relative abundances of bird species that used unburned Juncus marsh were similar to those in burned Juncus marsh in the spring period one year after the burn. Plant height at the burned Spartina marsh did not reach that of the unburned Spartina in 12 months; red-capped wren-spinetail (Spartonoica maluroides), a rare tall-grass-dependent species, settled burned parcels at lower relative abundances than in unburned habitat. Because species that first use the burned patches are very common and widespread in other habitats, and excessive burning may reduce available habitat for endangered or rare species, prescribed burns should be avoided in this region.

Slope wetlands exist where topographic or stratigraphic conditions allow ground water to intersect the surface, creating a zone of perennial or near-perennial moisture. The condition and resiliency of slope wetlands are, therefore, controlled by their hydrodynamics (i.e., the movement and action of water in the wetland) and recharge mechanisms. Understanding the mechanisms by which water flows into and through the wetland is essential for accurate assessment of potential indirect impacts and for the development of management measures geared toward preserving slope wetland functions. We investigated the physical and biological properties of twenty slope wetlands in southern California, USA to gain a better understanding of how their geologic setting influenced water movement through the wetlands and of the plant community composition in the wetland. Principle Components Analysis (PCA) separated the slope wetlands into three distinct groups based on geologic setting: those located in bedrock landslides, those associated with faults, and those associated with alluvial/colluvial deposits. Ground-water monitoring and hydrogeologic analysis showed that wetlands in alluvial/colluvial deposits respond quickly to precipitation, and subsurface water levels stay near the ground-surface elevation for extended periods of time. In contrast, subsurface water levels in bedrock landslide slope wetlands respond more slowly to precipitation, show greater variation over time, and ultimately decline more quickly after the cessation of recharge events. These observations (along with analysis of ground-water chemistry) indicate that wetlands in alluvial/colluvial deposits are likely supported by large, relatively stable volumes of ground water. In contrast, wetlands located in bedrock landslides are likely recharged from relatively localized ground-water sources with smaller storage volumes and greater interannual variability. Wetlands located along faults have an intermediate level of variation in moisture regime, indicating that their association with a fault may be providing a conduit for water delivery to the wetland. Plant species diversity did not differ between subclasses, although wetlands in alluvial/colluvial deposits supported slightly greater proportions of alkaline plant species. Understanding the different recharge characteristics of each subclass will allow for more informed decision-making regarding protection and management of slope wetlands.

Drainage, vegetation removal and harvesting, and vegetation restoration have a profound effect on carbon cycling in peatlands. Through laboratory incubations of 114 peat samples collected from the surface layer and just above and just below the water table at 13 sites, we examined the potential for carbon dioxide (CO₂) production under aerobic and anaerobic conditions and methane (CH₄) production under anaerobic conditions. CO₂ production rates ranged from 0.04 to 1.05 mg g⁻¹ d⁻¹ under aerobic conditions and 0.01 to 0.29 mg g⁻¹ d⁻¹ under anaerobic conditions. Rates of CO₂ production were generally smallest in the lower parts of the profiles and at the recently restored sites where deep peat was exposed at the surface; they were largest in the freshly-formed surface peat at the undisturbed bog and older restoration sites where a strong cover of vegetation had developed. The CO₂ production potentials were negatively correlated with the Von Post Index of decomposition, and aerobic:anaerobic production ratios averaged 4.3: 1. Largest rates of anaerobic CH₄ production occurred in samples close to the soil surface with fresh peat accumulation and a high water table, and smallest rates were in samples from the subsurface of sites with a low water table. Anaerobic CH₄ production was significantly positively correlated with aerobic and anaerobic CO₂ production. These production potentials show that drainage, harvesting, and restoration change the ability of the peat profile to produce and emit CO₂ and CH₄.

The spread of the invasive native clonal grass Elymus athericus is one of the most significant changes that have affected the plant communities of European salt marshes in the last decade. The goal of this study was to investigate the rate of this invasion and its impact on C cycling in a non-grazed salt marsh of the Mont Saint-Michel Bay (France). Aboveground net primary production (ANPP), litter quantity and quality, and decomposition rates were quantified in Elymus athericus and in the original plant communities (“control”). Since 1991, Elymus athericus has been replacing the characteristic plant communities at a rate of 4 ha yr⁻¹. ANPP was significantly higher in Elymus athericus (3011 ± 347 gDW m⁻² yr⁻¹ and 1181 ± 123 gC m⁻² yr⁻¹) than in the control (2028 ± 239 gDW m⁻² yr⁻¹ and 771 ± 76 gC m⁻² yr⁻¹) stands. Lignin content of Elymus athericus' litter was 3.5 times greater than in the litter of the control communities, explaining its accumulation under the vegetation (i.e., litter quantity was from 2 to 10 times greater under Elymus athericus than under the control vegetation). C mineralization in the sediment (expressed as rate of CO₂ per mass of sediment) was significantly lower under Elymus athericus than under the control vegetation. Our results suggest that Elymus athericus increased C trapping within the salt marsh and thus limits the potential for C exportation toward coastal waters.

Despite visual similarities between marshes and moderate-rich fens in the southern part of the western boreal forest of Canada, there are ecological and functional differences between the two wetland classes. Western boreal marshes have received little attention and are often difficult to distinguish from moderate-rich fens in appearance, especially when both are located at the edges of ponds and small lakes. We examined species assemblages, net above-ground production, decomposition, nutrient cycling, and environmental characteristics in five wetlands, all with approximately 1 m of peat. Based on TWINSPAN and DCCA, both wetland classes contain Carex aquatilis, but marshes were characterized by Carex utriculata, Carex atherodes, Lemna minor, Typha latifolia, and no mosses. Fens were characterized by Carex lasiocarpa and various species of brown mosses, and overall, they were more variable in species composition. There were also functional differences between the classes, with net above-ground production (especially vascular plant production) greater in marshes. Decomposition rates were higher in marshes, with Carex mass losses of 86% compared to 73% in the fens after 506 days. Comparisons of our data with previous years also indicate that high water levels promote decomposition and suggest that differences in the decomposition rates between marshes and fens may ultimately be controlled by hydrologic conditions and not surface-water nutrient dynamics. Nutrient dynamics and concentrations differed between wetland classes. Concentrations of phosphorus were higher in marsh plants and lower in the peat soil than in fens. Nitrogen concentrations were higher in marsh peat than fen peat. Based on the N:P quotients of the dominant vegetation, plants in both wetlands were more limited by available N than P. Surface-water concentrations of all nutrients were higher in marshes than fens, although even the fens can be considered eutrophic, with total phosphorus concentrations averaging approximately 100 μg L⁻¹. Surface-water levels were generally higher in the marshes, and 90% of the variation in environmental variables between the two peatland classes could be explained by surface-water level, alkalinity, chloride, ammonium, and potassium. Thus, we found that marshes and moderate-rich fens have characteristic species assemblages and that these two wetland classes can be distinguished based on environmental variables and ecosystem functions, despite the strong visual similarities between some fens and marshes.

This project used three different experiments to test the hypothesis that deposition of small amounts of sediment in wetlands alters plant diversity and soil properties. Greenhouse experiments using potting soil and Sagittaria latifolia were used with 0.5–2 cm sediment treatments and controls. Thirty 2 m X 2 m plots were established in a freshwater palustrine marsh, and the plots were monitored before and after the addition of 1, 2, or 4 cm of sediment to half of the plots. Large vegetated cores of native soil were removed from the wetland and monitored in the greenhouse before and after the addition of 2 cm of sediment. Greenhouse experiments showed that less than 2 cm of sediment had no effects on the growth of S. latifolia, while 2 cm of sediment significantly increased aboveground biomass but had no effect on matrix potential or oxidation-reduction potential. Field plots showed significant differences in bulk density, organic matter, and phosphorus resulting from addition of sediment but did not show differences in water levels, temperature, plant diversity, biomass, or stem density under any amount of added sediment. Soil cores showed a significant difference in bulk density and in matrix potential near the soil surface under wetter conditions but showed no significant differences in temperature, evapotranspiration, oxidation-reduction potential, or aboveground biomass. The lack of effect seen in the field plots is likely the result of a low effective loading rate relative to the greenhouse experiments and the dense plant cover and thick debris layer of the wetland. Observed changes in bulk density would alter the hydrologic functions of the wetland if these depths of sediment occurred over a larger area. The tolerable level of sediment for a wetland depends on the structure and function of the individual wetland.

To assess attributes of algal assemblages as indicators of salt marsh restoration, we chose eight pairs of salt marshes in North Carolina, USA, each pair with one restored marsh (from 1 to 28 years old) and a nearby existing salt marsh. Algae on both Spartina alterniflora and sediments (sediment algae) were collected in each marsh during spring and summer 1998 for assaying algal biomass (dry mass (DM), ash free dry mass (AFDM), chl a content, algal biovolume), algal species composition and diversity, and gross primary production. An attribute restoration ratio was calculated by dividing attribute values from each restored marsh by values from a paired reference marsh. Controlling for regional variation in reference marshes substantially increased precision in relations between attributes and the increase in age of restored marshes. The organic matter restoration ratio of sediments increased with age of restored marshes in both spring and summer. The algal biomass restoration ratios of epiphytes, calculated with algal biovolume and chl a, increased with restored marsh age in summer but not during spring. Biomass of sediment algae was not related to marsh age. The species diversity of sediment algae in summer showed an asymptotic relationship with sediment nutrient concentration. The similarity of diatom species composition between paired restored and reference sites increased with age of restored marshes during spring and summer. Primary production by epiphytic and sediment algae in summer showed site-specific changes and did not change consistently with marsh age. Algal biomass, algal diversity, and diatom species composition during summer were positively correlated with sediment nitrogen and phosphorus concentration. We concluded that other structural and functional development of restored wetlands, especially nutrient storage in sediments, regulates algal species composition and algal biomass accumulation, which can be used to evaluate salt marsh restoration.

Dating recent peat deposits (i.e., past ∼ 300 yrs of peat accumulation) has emerged as an important yet challenging task for estimating rates of organic matter accumulation and atmospheric pollutant deposition in peatlands. Due to their ombrotrophic nature and the tendency for Sphagnum-derived peat to have high cation exchange capacity, peatlands are ideal archives of atmospheric pollution. However, efforts to establish depth-age relationships in peats are complicated by the difficulty of dating deposits reliably. Assumptions underlying the techniques available for dating peat deposits often are poorly understood and generally untested. We outline the approaches used to establish depth-age relationships in peat chronologies, including brief descriptions of the theory, assumptions, methodology, and logistics of each technique. We include both continuous dating methods (i.e., methods based on ¹⁴C, ²¹⁰Pb, constant bulk density, acid-insoluble ash, moss increment, pollen density) and chrono-stratigraphic markers (i.e., fallout isotopes from the Chernobyl accident and nuclear weapons testing, pollen stratigraphies, isothermal remanence magnetism, charcoal particles, spherical carbonaceous particles, PAHs, PCBs, DDT, toxaphene) that can be measured in peat and correlated temporally with known historical events. We also describe the relatively new radiocarbon application of wiggle matching and use hypothetical data to highlight the potential of this developing technique for dating recent peat. Until the uncertainty associated with each of these dating approaches is clarified, we recommend employing multiple techniques to allow for corroboration between different methods.

In the twentieth century, there have been increases in Scots pine (Pinus sylvestris) coverage on peatlands in southern Sweden. In order to assess possible links to contemporary climate change, aerial photograph analysis and dendrochronology were combined to study recent pine cover changes at Anebymossen, a raised peat bog in south central Sweden. Multi-temporal analyses of three sets of panchromatic images from 1950 to 1993 showed a 30% increase of the marginal pine forest of the raised bog during that time, where a significant increase had occurred in the eastern part. Dendrochronological analyses were performed in two parts: the eastern part and the western part where the increase in pine coverage was considerably lower. The tree-ring growth patterns disclosed that a major event, most likely drainage, had occurred at Anebymossen in 1927, affecting tree growth at both sites. The effect of the drainage, which lowers the local ground-water table and hence promotes tree growth, was growth surges with a doubling of the annual increment rates. The effect was short lived in the western part, but continuous drainage in the eastern part caused growth enhancement until the beginning of the 1980s. We suggest that rather than being caused by climate change, the increase in pine coverage on Anebymossen was initiated by the considerable drainage in 1927. Since most peatlands in southern Sweden have been affected by anthropogenic activities, we suggest that it is difficult to make climatological interpretations of tree cover changes on peatlands using only aerial photograph analyses.

We characterized the post-disturbance recruitment window for red maple (Acer rubrum) in a southern Appalachian wetland using size-class distributions and forest stand models. The DBH and core age of understory and overstory trees were measured in 108 plots in forested (closed) and unforested (open) fen and floodplain sites at the Tulula Creek wetland complex (a southern Appalachian wetland in Graham County, North Carolina) in 1994 and 2001 as part of a larger ecological study. In addition, the heights of red maple seedlings were measured in 379 quadrats in an unforested floodplain in 1996 and 2001. We examined the temporal patterning of wetland recruitment using red maple size-class data in order to determine (1) the recruitment window for seedling colonization and (2) temporal recruitment patterning based on the size/age structure of established tree stands. Diameter and height distributions were compared with power function, negative exponential and quadratic models in order to determine goodness of fit using the coefficient of determination (R²). Diameter distributions and stand models showed that recruitment continued (at a diminishing rate) at sites that were last cleared 7, 14, and approximately 30 years earlier and ceased at a fourth site cleared approximately 45 years earlier. While there were minor recruitment fluctuations that possibly coincided with water-level changes, the unimodal size class distributions indicated that recruitment did not pulse subsequent to initial canopy disturbance. These results show that red maple readily colonized wetland habitats and that the recruitment window lasts at least twice as long as that reported in terrestrial systems. In addition, size-class distribution and regression analysis indicate that the colonization window is directly impacted by canopy disturbance and only indirectly influenced by water levels.

Approximately 7.3 hectares of wetlands, composed of six separate cells, were created to mitigate the loss of a 6-hectare, beaver-influenced, wetland-stream complex destroyed by the construction of a multi-purpose impoundment in the Cedar Run watershed in Fauquier County, Virginia, USA. The mitigation action physically replaced the lost wetlands and was judged successful in meeting planned objectives and regulatory requirements (which did not include standards for biota). A pre-project fish survey conducted in 1974 in the wetland-stream complex and three nearby streams provided a baseline condition from which to assess project impacts on fish, as determined from yearly surveys in the cells and the stream reach immediately upstream. In addition, fish communities were sampled at 157 stream locations within the northern Virginia Piedmont from 1997 to 1999 to establish a regional Index of Biotic Integrity (IBI) based on fish assemblages. A modification of that IBI was developed to assess the effectiveness of the mitigation based on 22 stream segments that were heavily influenced by beaver. Pre- and post-project conditions were assessed by gauging them against the wetland-stream complexes using this IBI. The IBI score for the mitigation area dropped from the pre-project 34 to 18 the first year after construction and ranged from 18 to 28 over the ten-year post-project monitoring period. A reduction in the number of native species was observed, and there was a dramatic shift in composition and relative abundance within key species groups. In general, the mitigation benefited species favoring lentic environments over those preferring lotic environments and had negative effects on trophic and habitat specialists and less tolerant species. Scores for the mitigation cells were lower than scores for the original wetlands for the following IBI metrics: number of darter species, number of minnow species, percent of the assemblage comprised of the single most dominant species, percent of tolerant individuals, percent of benthic invertivores, and percent of specialist carnivores minus tolerants. Upstream reach IBI scores also diminished over the same 10-year period, although more gradually. The IBI showed that, despite meeting all regulatory requirements, the mitigation failed to replace the original fish community in the wetland-stream complex and adversely impacted additional stream habitat. Using tools such as an IBI to monitor biological condition can help planners effectively mitigate unavoidable project impacts and avoid the unintended loss of important natural resources caused by compensatory mitigation actions.

Orchid Meadows is a long-term wetland research and monitoring site on the Coteau des Prairie in extreme east-central South Dakota, USA. It is a 65-ha Waterfowl Production Area with numerous temporary, seasonal, and semi-permanent wetlands. Ground water and surface water have been monitored at the site from 1987 to 1989 and from 1993 to the present. Vegetation has been monitored since 1993. The monitoring record includes two nearly back-to-back weather extremes: a drought in the late 1980s and a deluge in the early- to mid-1990s. Wetlands differed sharply in water levels between 3-yr dry and wet periods. For example, the time of inundation ranged among semi-permanent wetlands from 13 to 71 percent during the dry years to 100 percent during the wet years, while for seasonal wetlands, it was 0–29 percent and 46–100 percent, respectively, during dry and wet periods. Temporary wetlands had no surface water during the dry period but had standing water 0–67 percent of the time during the deluge years. The highest ground-water levels during the dry period were lower than most levels during the wet period. The difference in the water-table elevations of temporary wetlands between the periods was as much as 4 m. Ground-water levels near semi-permanent wetlands were considerably more stable (annual range of 0.3–1.6 m) than those near temporary wetlands (1.3–2.5 m). The results support the concept that weather extremes drive the wetland cover cycle and other key ecological processes in prairie wetlands. The new data from Orchid Meadows, together with other long-term data sets from North Dakota and Saskatchewan, Canada, are useful for many research purposes, including the parameterization and testing of models that simulate the effects of climate variability and climate change on prairie wetland ecosystems.

Previous research has demonstrated that beavers (Castor canadensis) dramatically alter fish habitat in streams by their dam-building activities. Although less well-known, beavers also flood closed peatlands by damming seepage rather than streamflow. Our study focuses on the establishment of fish communities in isolated beaver ponds created in small, ombrogenous peatlands lacking any open water prior to beaver occupation. We selected 16 ponds that ranged in age from 4 to 42 years and three unaltered peatlands to determine whether beaver promote the use of peatlands by fish and if the patterns of individual species were related to macrophyte density. Fish were present in ponds as young as four years old, and five of the six species of fish were present in ponds ≤16 years old. Submersed macrophyte abundance explained 40% of the variation in fish diversity. Rapid colonization of fish in beaver-altered peatlands provides further evidence of how beavers increase the complexity of biological food webs in boreal regions. Moreover, this work provides an even greater understanding of the historical role of beavers as ecosystem engineers in peatland dominated landscapes.

Playas are temporarily ponded, shallow, intermittent lakes found in the arid southwest United States formed by rainfall and runoff in the wet season. Because playas are considered “Waters of the United States” (WoUS) under Federal Regulations 33 CFR 328.3 [a], their jurisdictional extent is delineated by either observation of ponded water or physical characteristics that represent ordinary high water marks that remain after the water has receded. To date, no surface hydrologic studies have described the frequency and duration of ponded water within desert playa systems to facilitate the understanding of “ordinary” for delineation purposes. To establish a baseline to support further the concept of “ordinary,” we used 20 years of historical satellite imagery of playas in the western Mojave Desert, California, in combination with 59 years of precipitation records, to provide a case study of frequency and duration of ponding in playas in the arid southwestern United States. Ponding was found to occur for at least 16 days, with a frequency of 51% or approximately every other year. We estimated the average antecedent precipitation needed to initiate ponding to be 8.29 cm. In years when rainfall exceeded 8.29 cm between October and March, the playas also ponded for 16 days into the growing season (March–November). The total length of the ponding period through the wet season ranged between 1 and 32 weeks, with a predictable relationship between length of inundation and total rainfall during the wet season. This range of occurrence of ponded water on these arid playas expresses the climatically unevenly distributed precipitation pattern, both spatial and temporally. Analysis of the ponding duration and frequency from this study site acts as a baseline for further refinement of the concept of ordinary high water and provides a basis for further development of field indicators for delineation purposes of arid southwestern playas.

The objectives of this paper are to summarize existing knowledge on the hydrologic characteristics of tidal marshes in the New York/New Jersey (NY/NJ) Estuary, to document the extensive linkages between hydrology and tidal marsh function, to underline their importance in designing restoration projects, and to identify research needs in this area. Hydrologic processes are responsible for the evolution, inter- and intra- marsh variability, and functional value of tidal marshes. Hydrology also controls the movement of materials and organisms between estuaries, wetlands, uplands, and the atmosphere. The importance of hydrology to tidal marsh function is widely recognized by the scientific community. Hydrologic research in tidal wetlands of the NY/NJ Estuary, however, is lacking. Anthropogenic development activities have resulted in drastic losses of tidal wetland value, and restoration is now finally a priority in many of the region's natural resource management plans. The success of tidal marsh restoration efforts depends on how appropriately hydrologic factors and their interdependencies are recognized and incorporated into design; yet, little guidance about how best to restore tidal marsh hydrology is available. There is a need to document better the hydrologic characteristics of existing and historical tidal wetlands, to improve hydrologic modeling capabilities, and to accompany other ecological investigations in tidal marshes with hydrologic documentation.

Seedling establishment is an important means of re-colonizing herbicide-treated and burned Phragmites australis marshes and of filling in newly created or naturally forming marshes. Knowing the differential sensitivity of the various species to sulfide better enables us to predict which plants are likely to colonize given areas (i.e., be it desirable species or P. australis). This study focuses on the sulfide sensitivity of the seedlings of five plant species that may re-colonize the cleared marsh surface either from wild seed stock or introduced propagules: Spartina alterniflora, Spartina patens, Setaria magna, Atriplex triangularis, and P. australis. Seedlings were grown in culture tubes in semi-solid agar media containing Hoagland's nutrients; sulfide treatments included levels of sulfide from 0 to 8 mM. Parameters measured included number of leaves, number of lateral roots, shoot length, root length, leaf length, and biomass. Setaria magna proved to be the most sensitive to sulfide, followed in order by A. triangularis, S. patens, P. australis, and S. alterniflora. Differences in edaphic sulfide are not likely to be helpful in favoring S. magna, A. triangularis, or S. patens over P. australis. Phragmites australis was compared to S. alterniflora in a second experiment with six concentrations of sulfide between 0 and 2.0 mM. Results indicated that sulfide levels between 0.4 and 0.9 mM would favor seedling establishment of S. alterniflora over P. australis, and at 0.9 mM, S. alterniflora seedlings would have the decided advantage.

Salt marsh restoration practices based on the reintroduction of tides to hydrologically-altered wetlands may be hindered by a lack of specific knowledge regarding plant community response to environmental change. Since saltmarsh plant communities are controlled by physical stress tolerance and competition, we conducted a field experiment that measured effects of saltwater flooding and competitive interactions on plants as a guide for predicting habitat response to tidal restoration. Six plant species of New England salt marshes were studied: halophytes Spartina alterniflora, Spartina patens, and Juncus gerardii and brackish invasive species Phragmites australis, Typha angustifolia, and Lythrum salicaria. Plant shoots were transplanted across a gradient of three flooding and three salinity regimes and arranged into pair-wise competitive combinations. After one growing season, saltwater flooding was found to decrease transplant survival, biomass production, and/or relative growth for all species. Reduction in halophyte growth was largely due to increased flood duration; brackish species were most reduced by increased salinity. Interspecific competition also influenced species growth, although the short duration of the study may have weakened these effects. Transplants paired with S. alterniflora had reduced growth, but combinations with Juncus produced increased growth. Standardized factors of stress tolerance and relative competitive strength were derived for the six study species as a framework for understanding community-level changes in marshes. As an aid to resource managers, experimental results can be used to predict plant community response to existing and potential alterations in saltmarsh tidal hydrology.

We describe a conceptual model, the wetland continuum, which allows wetland managers, scientists, and ecologists to consider simultaneously the influence of climate and hydrologic setting on wetland biological communities. Although multidimensional, the wetland continuum is most easily represented as a two-dimensional gradient, with ground water and atmospheric water constituting the horizontal and vertical axes, respectively. By locating the position of a wetland on both axes of the continuum, the potential biological expression of the wetland can be predicted at any point in time. The model provides a framework useful in the organization and interpretation of biological data from wetlands by incorporating the dynamic changes these systems undergo as a result of normal climatic variation rather than placing them into static categories common to many wetland classification systems. While we developed this model from the literature available for depressional wetlands in the prairie pothole region of North America, we believe the concept has application to wetlands in many other geographic locations.

As in most large capital cities, urban stormwater discharging into Port Jackson (Sydney) is highly enriched in a wide range of contaminants, which has resulted in degradation of the receiving basin waters and bottom sediments. The objective of the current investigation was to determine the removal efficiency of contaminants in urban stormwater by a wetland constructed in the Sydney catchment. The wetland (700 m²) drains a residential urban catchment of about 480,000 m² comprising predominantly houses, streets, gardens, and street parking areas. Samples of stormwater influent and effluent were obtained during rainfall events between April and June 2000. Eight samples were collected at the inlet and outlet to the wetland during each event and analyzed for nutrients, trace metals, total suspended solids (TSS), and organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs). Water quality parameters (temperature, dissolved oxygen, pH, turbidity, conductivity) were measured concurrently. The average removal efficiency of trace metals Cr, Cu, Pb, Ni, and Zn was 64%, 65%, 65%, 22%, and 52%, respectively for the six events measured, whereas for Fe and Mn, removal efficiencies were negative for most events (mean−84% and−294%, respectively). The average removal efficiency of NO_x and TN was 22% and 16%, respectively. The average removal efficiencies of total Kjeldahl nitrogen (TKN) and total phosphorus (TP) were 9% and 12%, respectively. During four high-flow events, the removal efficiency of TSS in stormwater effluent from the wetland was between 9% and 46%; however, substantially higher TSS concentrations were observed in effluent than influent waters during two very high-flow events (removal efficiency−98% and−67%). Fecal coliform counts in the stormwater in this catchment are high (maximum: 620,000 cfu/100 ml), but mean removal efficiency was 76% (range 26% to 98%) during the four high-flow events monitored. Nevertheless, most samples from the outflow exceeded the Public Health criterion for secondary contact (e.g., boating) of 1000 cfu/100 ml. Concentrations of organochlorine pesticides and PAHs in stormwater were below analytical detection. Although highly variable, lower concentrations of Cr, Cu, Ni, Pb, Zn, NO_x, TN, and fecal coliform in the stormwater effluent compared to influent waters indicates that the wetland was moderately efficient in removing contaminants from urban stormwater.

Seasonal riparian seedbed temperatures were measured and germination of Carex utriculata and C. nebrascensis seeds was tested in relation to chilling, perigynia removal, incubation temperature, and light to help guide propagation and direct seeding of these species for riparian restoration. Diurnal temperatures of riparian seedbeds at two sites in Strawberry Valley, Utah, USA ranged from 3.1 to 11.2° C in May to 9.5 to 24.1° C in August when water was generally available for seed germination. Pre-incubation treatments of chilling at 5° C for 7 to 150 days and perigynia removal increased germination of 2-year-old seeds of these species but were not necessary for high germination percentages (>89%) when seeds were incubated in light under a summer temperature regime (10 to 24° C). Seeds aged 0.5 and 1.5 years had lower germination percentages than 2-year-old seed but also had adequate germination percentages (> 20%) for greenhouse propagation without pre-treatments when incubated in light at the summer temperature regime. After 5.5 years of storage at room temperatures, germination of C. utriculata was negligible, but that of C. nebrascensis was > 35%. Seeds of both species that were overwintered in seed bags in riparian microsites had high germination percentages (>80%) when retrieved the following summer and incubated at a summer temperature regime in light. Although direct seeding in fall would allow natural chilling and potentially high germination percentages the following spring or summer, the risk of seed loss or excessive burial is great during high spring stream flows. A better strategy is to surface-seed wet seedbeds in early summer after peak flows have receded and temperature and light conditions are conducive to high germination percentages.