Wetland Restoration Projects Research Articles

Variation of soil nutrients and particle size under different vegetation types in the Yellow River Delta

The Yellow River Delta wetland, located at the southern coast of Bohai Gulf, provides important ecosystem services such as flood control, water purification, biodiversity conservation, nutrient removal and carbon sequestration, shoreline stabilization, tourism attraction and wetland products maintains in the Yellow River Delta. This study assessed how agricultural activities in a reclamation wetland changed soil pH, soil electric conductivity, soil nutrient and soil particle size as compared to natural vegetation by using a combination of field experiments and lab analysis. The vegetation type included adjacent alfalfa field (Medicago sativa), cotton field (Gossypium spp.), Chinese tamarisk shrub (Tamarix chinensis), and reed marsh (Phragmites sage). The results indicated that the soil pH was higher (pH>8) in alfalfa field and cotton field, and alfalfa field and reed marsh had significant function in reducing soil salt content, soil electric conductivity of alfalfa field at 0–30cm were 140.38±14.36, 114.48±14.36, 125.30±11.37μs/cm. The effect of different vegetation types on soil nutrient was significant (P<0.05). Soil organic matter at 0–10cm in Chinese tamarisk shrub and reed marsh was 21.66±3.82g/kg and 16.51±4.60g/kg, which was higher than that of alfalfa field (10.47±2.36g/kg) and cotton field (9.82±1.27g/kg), but soil total nitrogen content in alfalfa field was the highest, which is significantly higher than that of cotton field, Chinese tamarisk shrub and reed marsh(P<0.05), the content of soil total nitrogen at 0–10cm and 10–20cm was 7.67±0.38g/kg and 5.97±0.51g/kg, respectively, while the content of available P and available K was reversed. The difference of soil particle size between layers was not significant (P>0.05), the sand content of Chinese tamarisk shrub soils in 0–10cm was the highest, the next was alfalfa field and cotton field, and the content of silt and clay in reed marsh was higher than the others. The correlation and significant degree between soil particle size and soil nutrient was related with vegetation types, and soil organic matter was significantly positively correlated with soil silt and clay content on the alfalfa field. The results demonstrated that wetland cultivation was one of the most important factors influencing on the nutrient fate and reserves in soil, which could lead to rapid nutrient release and slow restoration through abandon cultivation. Consequently, compared with cotton field, alfalfa field is more favorable to sustainable management of wetland cultivation in the Yellow River Delta. It should be considered in wetland restoration projects planning.

Three-Dimensional Modeling of Storm Surge and Inundation Including the Effects of Coastal Vegetation

Two-dimensional (2D) and three-dimensional (3D) hydrodynamic models are used to simulate the hurricane-induced storm surge and coastal inundation in regions with vegetation. Typically, 2D storm surge models use an enhanced Manning coefficient while 3D storm surge models use a roughness height to represent the effects of coastal vegetation on flow. This paper presents a 3D storm surge model which accurately resolves the effects of vegetation on the flow and turbulence. First, a vegetation-resolving 1DV Turbulent Kinetic Energy model (TKEM) is introduced and validated with laboratory data. This model is both robust enough to accurately model flows in complex canopies, while compact and efficient enough for incorporation into a 3D storm surge-wave modeling system: Curvilinear Hydrodynamics in 3D-Surface WAves Nearshore (CH3D-SWAN). Using the 3D vegetation-resolving model, three numerical experiments are conducted. In the first experiment, comparisons are made between the 2D Manning coefficient approach and the 3D vegetation-resolving approach for simple wind-driven flow. In a second experiment, 2D and 3D representations of vegetation produce similar inundations from the same hurricane forcing, but differences in momentum are found. In a final experiment, varying inundation between seemingly analogous 2D and 3D representations of vegetation are demonstrated, pointing to a significant scientific need for data within wetlands during storm surge events. This study shows that the complex flow structures within vegetation canopies can be accurately simulated using a vegetation-resolving 3D storm surge model, which can be used to assess the feasibility for future wetland restoration projects.

On the challenges of modeling the net radiative forcing of wetlands: reconsidering Mitsch et al. 2013

Wetlands play a role in regulating global climate by removing carbon dioxide (CO2) from the atmosphere and sequestering it as soil carbon, and by emitting methane (CH4) and nitrous oxide (N2O) to the atmosphere. In a recent article in this journal (Mitsch et al. Landscape Ecol 28:583–597, 2013), CO2 sequestration and CH4 emissions were modeled for several freshwater wetlands that vary in vegetation type, climate, and hydrology. The authors of that study made significant errors that caused them to underestimate the importance of wetland CH4 emissions on climate dynamics. Here, I reanalyze the Mitsch et al. dataset and show that all of their wetlands had an initial warming effect but eventually caused negative net radiative forcing within ~60–14,000 years, depending on the ratio of CO2 sequestration to CH4 emissions. The addition of a N2O component to the model suggested that typical wetland N2O emission rates would contribute only a minor burden to wetland radiative forcing, although specific application of this three-gas model is limited by the paucity of sites where CO2 sequestration, CH4 emission, and N2O exchange rates have all been measured. Across the landscape, many natural wetlands may already cause negative net radiative forcing when integrated over their lifetime. However, caution should be applied when using carbon sequestration as a rationale for designing wetland construction and restoration projects since freshwater wetlands may have a net positive (warming) effect on climate for decades to centuries or longer.

Effects of Wetland Management on Carrying Capacity of Diving Ducks and Shorebirds in a Coastal Estuary

With global loss of natural wetlands, managed wetlands increasingly support energy requirements for wintering shorebirds and waterfowl. Despite numerous studies of avian bioenergetics in freshwater systems, less is known of the energetic capacity of estuarine systems. In San Francisco Bay, managed saline ponds converted from former commercial salt evaporation ponds form part of the largest wetland restoration project on the Pacific coast of North America. A daily-ration model was applied to assess carrying capacity for diving ducks and shorebirds during four winter seasons (2007–2010) in seasonal and circulation ponds, each in two salinity classes. Diving ducks comprised an estimated 35,450 ± 1,559 ( ± SE) in average years and 45,458 ± 1,653 in peak years with > 95% in circulation ponds. Shorebirds comprised 64,253 ± 14,838 ( ± SE) in average years and 108,171 ± 4,854 in peak years with > 64% in seasonal ponds. Macroinvertebrate energy density was highest in mesohaline (5–30 ppt) circulation ponds and lowest in seasonal ponds for both guilds. Energy requirements for diving ducks in mesohaline followed by low-hyperhaline (30–80 ppt) circulation ponds were mostly met by available prey energy. Available energy for shorebirds was substantially less than they required in seasonal ponds but exceeded their needs in mesohaline circulation ponds. Mesohaline circulation ponds supported 9,443 ± 1,649 ( ± SE) shorebird use-days·ha-1 of accessible habitat and 2,297 ± 402 diving duck use-days·ha-1 of accessible habitat, twice the capacity of low-hyperhaline circulation ponds and greater than five times that of seasonal ponds for both guilds. Our results indicated that reducing salinity to mesohaline levels and altering water depth to increase accessibility substantially increased energy available for these species in estuarine managed ponds.

Germination of 14 freshwater wetland plants as affected by oxygen and light

Oxygen and light are factors that can affect seed germination of wetland plants. We selected seeds from 20 plant species found in temperate eastern North American marsh and wet meadow wetlands, ranging from obligate wetland (OBL), facultative wetland (FAC) and upland (UPL) species. In growth chambers we tested germination success under controlled manipulations of O2 concentration (low [<1%] and atmospheric [∼20%]) and light levels (full light, half light and dark). Our objective was to (1) determine whether oxygen, light and their interaction facilitate germination of wetland seeds; (2) whether timing of germination is affected by oxygen and light; and (3) whether germination is related to wetland functional groups. Six species did not germinate. Of the 14 species that did germinate, a non-native ruderal (Echinochloa crus-galli) had the greatest germination success. However, we found that low O2 reduced germination success of all but three species (Rudbeckia triloba, Sagittaria latifolia and Typha latifolia). Reduction in light levels only reduced germination success of S. latifolia. We conclude that the physiological constraints that control germination operate independently for oxygen and light. It is important to know and anticipate oxygen and light levels when designing a wetland restoration project so that the proper species can be sown that can germinate under the specific conditions. Restoration planners should be aware that anoxic and hypoxic conditions seem to promote the germination of weedy and potentially invasive native and non-native species.

A Realistic Role for Reference in Wetland Restoration

Wetland restoration projects are often evaluated for success or failure by comparing attributes of restored ecosystems to undisturbed reference ecosystems. This method of evaluation has several flaws, including site-specific responses of restored ecosystems to topographic and geomorphic changes during degradation and restoration, the substantial differences in structure and function of early (restored) and mature (reference) ecosystems, and the inherent variability that exists for ecosystems that may not be represented in reference systems. We need a better framework for evaluating restoration success. Success could be demonstrated by using ecosystem attributes that indicate ecosystem integrity and maturation over time, such as: stable landforms, native plant community development, internal carbon and nutrient storage and cycling, connectivity within the broader landscape, ecosystem heterogeneity, and increasing complexity in species and community diversity. A more realistic role for reference areas in wetland restoration is useful information on structural and functional attributes of ecosystems and an indication of the natural variability that exists in ecosystems that we hope to emulate. Ultimately though, success in wetland restoration depends on our ability to establish conditions that promote ecosystem maturation and integrity and reference systems may be of limited value to evaluate this success.

Bog Turtle (Glyptemys muhlenbergii) Wetland Habitat: an Emphasis on Soil Properties

Bog turtles (Glyptemys muhlenbergii) access saturated wetland soils and move through them to thermoregulate, find cover, and hibernate. Variability in the physical properties of the soil that affects suitability for turtle use is little understood. We identified dominant soil series and measured soil organic carbon (SOC) content and particle size in the top 18 cm of surface soils from Southwestern Virginia wetlands frequently used by bog turtles and similar wetlands not known to be used. A static cone penetrometer was used to evaluate soil strength in specific locations where bog turtles were found and adjacent random areas. Soils were poorly developed alluvium with aquic soil regimes. Levels of SOC were greater in locations with more continuous surface saturation and averaged 10% in the wettest locations. Proportions of sand, silt, and clay in wetlands were consistent with loam and silt loam textures. Levels of SOC and dominant particle sizes were not different in similarly saturated areas of wetlands that were frequently used or not known to be used by bog turtles. However, some wetlands not known to be used completely lacked areas that were always saturated. Based on penetrometer data, bog turtle use was centered on low strength soils. The physical qualities of surface soils in bog turtle wetlands result from the depositional environment and hydrology. The soil information derived from this study may assist biologists to determine whether wetlands are used by bog turtles, and also establishes reference soil conditions for use during wetland restoration projects that occur within the geographic range of the bog turtle.

Chlorinated Solvent Treatment Wetland

AbstractA first‐of‐its‐kind wetland restoration project was completed in October 2000 to treat trichloroethene‐(TCE‐)impacted groundwater from a former manufacturing facility prior to discharge into a highly valued recreational surface water body in the upper Midwest. This article summarizes the design, construction, operation, and effectiveness of the restored wetland. The groundwater‐surface water discharge zone at the site was restored as a wetland to improve the natural degradation of TCE and subsequent degradation by‐products. For the past 11 years, the treatment wetland performance was evaluated by monitoring the wetland vegetation, wetland hydraulics, and water chemistry. Water quality data have been used to assess the wetland geochemistry, TCE and TCE‐degradation by‐product concentrations within the wetland, and the surface water quality immediately downgradient of the wetland. The treatment wetland has been performing according to design, with TCE and TCE‐degradation by‐products not exceeding surface water criteria. The monitoring results show that TCE and TCE‐degradation by‐products are entering the treatment wetland via natural hydraulic gradients and that the geochemistry of the wetland supports both reductive dechlorination (anaerobic degradation) and cometabolic degradation (aerobic degradation) of TCE and TCE‐degradation by‐products: cis‐ and trans‐1,2‐dichloroethene and vinyl chloride. © 2013 Wiley Periodicals, Inc.

Exploring preferences and non-use values for hidden archaeological artefacts: a case from Denmark

This paper presents a choice experiment study of a proposed wetland restoration project which aims to preserve archaeological artefacts from Stone Age villages which are presently buried within the topsoil. Wetland restoration can avoid destruction of the artefacts due to agricultural cultivation and drainage, and in addition improve biological diversity and recreational opportunities. The results indicate that even though the artefacts are not visible or usable for the population of today, but may contain information and potential value for future generations, the strongest preferences displayed is for ensuring permanent protection of archaeological artefacts, rather than biological diversity and recreational opportunities. The results are discussed in relation to the Prospect Theory: people value a loss of cultural heritage higher than a gain of new cultural goods or services. This insight is of general interest to cultural economics and cultural policy, especially with respect to heritage protection.

Does human perception of wetland aesthetics and healthiness relate to ecological functioning?

Wetland management usually aims at preserving or restoring desirable ecological characteristics or functions. It is now well-recognized that some social criteria should also be included. Involving lay-people in wetland preservation or restoration projects may mean broadening project objectives to fit various and potentially competing requirements that relate to ecology, aesthetics, recreation, etc. In addition, perceived value depends both upon expertise and objectives, both of which vary from one stakeholder population to another. Perceived value and ecological functioning have to be reconciled in order to make a project successful. Understanding the perceptions of lay-people as well as their opinions about ecological value is a critical part of the development of sustainable management plans. Characterizing the environment in a way that adequately describes ecological function while also being consistent with lay perception may help reach such objectives.This goal has been addressed in a case study relating to wetlands of the Ain River (France). A photo-questionnaire presenting a sample of photographs of riverine wetlands distributed along the Ain River was submitted to 403 lay-people and self-identified experts. Two objectives were defined: (1) to identify the different parameters, whether visual or ecological, influencing the perception regarding the value of these ecosystems; (2) to compare the perceptions of self-identified experts and lay-people.Four criteria appear to strongly influence peoples' perceptions of ecological and aesthetical values: water transparency and colour, the presence and appearance of aquatic vegetation, the presence of sediments, and finally, trophic status. In our study, we observed only a few differences in perception. The differences primarily related to the value assigned to oligotrophic wetlands but even here, the differences between lay and expert populations were minimal. These results support the idea that it is possible to implement an integrated and participative management program for ecosystems. Our approach can provide a shared view of environmental value facilitating the work of managers in defining comprehensive goals for wetland preservation or restoration projects.

Hydrologic Connectivity to Streams Increases Nitrogen and Phosphorus Inputs and Cycling in Soils of Created and Natural Floodplain Wetlands

Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

Review of Key Technique Research on the Field of Vegetation Restoration in Beach Wetlands

The study wetland vegetation restoration technology system and representative beach wetland restoration projects at home and abroad are summarized. Technology system of wetland vegetation restoration mainly includes engineering technology and biological technology. Ecological restoration research of coastal wetland in China mainly concentrated in the Yellow River Delta, the southeast coastal mangrove wetlands, coastal beaches of Jiangsu and the coastal wetlands in Shanghai Fengxian District. Finally, the issues existed in current research field were pointed out. The research fields need to be strengthened for the detailed field investigation and laboratory analysis of soil, vegetation, hydrology, meteorology, etc. According to the actual situation of wetland beaches, wetland site type will be divided. Suitable salt-tolerant plant varieties should be filtered and the mudflat wetland vegetation recovery key technologies should be explored.

Wetland and floodplain habitats management and solutions in Lower Meadow of Prut Natural Park

The pressure of economic development from the last 50 years in the area of Prut river, the protection measures against floods by building dams in the major river bed and the building of the hydrotechnical knot Stânca-Costeşti have been the causes of the transformation of the typical habitats in the humid areas at the border of Prut river, thus of the flood area favouring the breeding of fish and birds, endangering the ecological integrity of the area eco-system complex. In the past, Romanian Waters National Company the main manager of the water resources from Romania has started the preparation at the request of the Ministry of Water Forest and Environment Protection the inventory of the wetland and floodplains at national level, including the potential for restoration according with the particular case from Romania, where the process of land restitution to the previous owners is one important problem even in present time. In Prut catchment area is presented a large number of existing wetlands with a large restoration potential (about 200 wetlands recorded for whole Prut basin, many of them are less than 1 sqkm surface). It has to be mentioned that several wetlands which in present are in natural stage are included or will be included in the List of Protected Areas under the legislation preservation. In this regard the planning of wetlands and floodplains rehabilitation is underdevelopment and will depend by the finalization of the land restitution action. For all the types of existing habitats housing a large variety of fauna (especially avifauna), sedentary as well as migrating or passing fauna, the Maţa – Rădeanu humid area, with a surface of 386 ha, is similar to the special preservation areas from the Danube Delta. Among the protected areas within lower Prut basin, according to the criteria of habitat identification, three of them ( Ostrovul Prut, Lower Prut river meadow and Vlascuta swamp ) have been indicated to include some wetlands as well. Also, we propose the following potential demonstration sites for wetland management and restoration projects in the Lower Prut basin: Prut flood plain, downstream of Sovarca swamp , up to the mouth point in the Danube; Brates Lake located NE from Galaţi city, connected with the Prut river by the valley of Ghimia brook and Horincea hydrographical basin . Potential solutions for wetland floodplain habitats management involve technical and organisational issues, but some severe law aspect as well. The hydro potential of the sub-basins of this stream opens the door to elaborating an unified scheme in line with landscape features, hydrology and geology of the area. In this respect a complex arrangement of Horincea subbasin, Oancea, Bisericii and Stoenesei valleys which are located in an area of moisture deficit becomes essential. To complete the sub-basin planning, they should be viewed as indivisible natural units. The entire range of hydrotehnical works in this basin aimed to regulate the water stream in order to to avoid negative effects of flooding and must nevertheless respect the principles of ecological planning in order to avoid failures occurring after the completion of this type of works. Regarding the industrial and diffuse pollution which have an impact on Prut ecology and water quality, this being closely linked with the ecology of the floodplain forested corridor and the existing wetlands, the situation is much severe in the upper part of the basin, based on a large concentration of industry, agriculture and human settlements in comparison with the lower Prut where the impact is much smaller. We mention this can be subject for another study of ecological issues in this basin. When considering the environmental planning should start from the principle that the streams in the Prut basin represent simultaneously ways of circulation, tanks and complex ecological zones which are in strict interaction with the surrounding areas.

Compensatory Stream and Wetland Mitigation in North Carolina: An Evaluation of Regulatory Success

Data from a probability sample were used to estimate wetland and stream mitigation success from 2007 to 2009 across North Carolina (NC). "Success" was defined as whether the mitigation site met regulatory requirements in place at the time of construction. Analytical results were weighted by both component counts and mitigation size. Overall mitigation success (including preservation) was estimated at 74% (SE=3%) for wetlands and 75% (SE=4%) for streams in NC. Compared to the results of previous studies, wetland mitigation success rates had increased since the mid-1990s. Differences between mitigation providers (mitigation banks, NC Ecosystem Enhancement Program's design-bid-build and full-delivery programs, NC Department of Transportation and private permittee-responsible mitigation) were generally not significant although permittee-responsible mitigation yielded higher success rates in certain circumstances. Both wetland and stream preservation showed high rates of success and the stream enhancement success rate was significantly higher than that of stream restoration. Additional statistically significant differences when mitigation size was considered included: (1) the Piedmont yielded a lower stream mitigation success rate than other areas of the state, and (2) recently constructed wetland mitigation projects demonstrated a lower success rate than those built prior to 2002. Opportunities for improvement exist in the areas of regulatory record-keeping, understanding the relationship between post-construction establishment and long-term ecological trajectories of stream and wetland restoration projects, incorporation of numeric ecological metrics into mitigation monitoring and success criteria, and adaptation of stream mitigation designs to achieve greater success in the Piedmont.

Late Holocene Marsh Expansion in Southern San Francisco Bay, California

Currently, the largest tidal wetlands restoration project on the US Pacific Coast is being planned and implemented in southern San Francisco Bay; however, knowledge of baseline conditions of salt marsh extent in the region prior to European settlement is limited. Here, analysis of 24 sediment cores collected from ten intact southern San Francisco Bay tidal marshes were used to reconstruct spatio-temporal patterns of marsh expansion to provide historic context for current restoration efforts. A process-based marsh elevation simulation model was used to identify interactions between sediment supply, sea-level rise, and marsh formation rates. A distinct age gradient was found: expansion of marshes in the central portion of southern San Francisco Bay dated to 500 to 1500 calendar years before present, while expansion of marshes in southernmost San Francisco Bay dated to 200 to 700 calendar years before present. Thus, much of the tidal marsh area mapped by US Coast Survey during the 1853–1857 period were in fact not primeval tidal marshes that had persisted for millennia but were recently formed landscapes. Marsh expansion increased during the Little Ice Age, when freshwater inflow and sediment influx were higher than during the previous millennium, and also during settlement, when land use changes, such as introduction of livestock, increased watershed erosion, and sediment delivery.

Implications of multi-scale sea level and climate variability for coastal resources

While secular changes in regional sea levels and their implications for coastal zone management have been studied extensively, less attention is being paid to natural fluctuations in sea levels, whose interaction with a higher mean level could have significant impacts on low-lying areas, such as wetlands. Here, the long record of sea level at Key West, FL is studied in terms of both the secular trend and the multi-scale sea level variations. This analysis is then used to explore implications for the Everglades National Park (ENP), which is recognized internationally for its ecological significance, and is the site of the largest wetland restoration project in the world. Very shallow topographic gradients (3–6 cm per km) make the region susceptible to small changes in sea level. Observations of surface water levels from a monitoring network within ENP exhibit both the long-term trends and the interannual-to-(multi)decadal variability that are observed in the Key West record. Water levels recorded at four long-term monitoring stations within ENP exhibit increasing trends approximately equal to or larger than the long-term trend at Key West. Time- and frequency-domain analyses highlight the potential influence of climate mechanisms, such as the El Nino/Southern Oscillation and the North Atlantic Oscillation (NAO), on Key West sea levels and marsh water levels, and the potential modulation of their influence by the background state of the North Atlantic Sea Surface Temperatures. In particular, the Key West sea levels are found to be positively correlated with the NAO index, while the two series exhibit high spectral power during the transition to a cold Atlantic Multidecadal Oscillation (AMO). The correlation between the Key West sea levels and the NINO3 Index reverses its sign in coincidence with a reversal of the AMO phase. Water levels in ENP are also influenced by precipitation and freshwater releases from the northern boundary of the Park. The analysis of both climate variability and climate change in such wetlands is needed to inform management practices in coastal wetland zones around the world.

Hydrological modelling of tidal re-inundation of an estuarine wetland in south-eastern Australia

Wetland restoration is becoming more common across the globe, encouraged by an increasing number of success stories, and facilitated by emerging environmental conservation and offset legislation. However, much care is still required as the ‘art and science’ of wetland restoration is considered to be rudimentary compared to the complexity of natural wetland environments (Zedler, 2001). Gaining a sound appreciation of wetland hydrology is fundamental to predicting future ecological function in response to wetland restoration projects (Callaway, 2001). In this regard, hydrodynamic numerical models can be used to predict hydrological behaviour and wetland inundation extents, providing that the models are an adequate representation of the real-world environment.Wetland restoration commenced at Hexham Swamp, Australia, in 2008. For the past 40 years this former estuarine wetland has been degraded by hydrological modifications resulting from the operation of one-way floodgates at its downstream end. The restoration project involves progressively opening the floodgates and allowing saline tidal waters to re-inundate the wetland flats, which have become dominated by a vast monoculture of Phragmites australis. A TUFLOW hydrodynamic model of Hexham Swamp was developed to identify areas within the wetland likely to be influenced by opening the floodgates. The model's predictive capacity was improved during the course of the project by the collection of high resolution ground elevation data and advancements in the numerical representation of the floodgates structure. Calibration of the numerical model was undertaken progressively as the restoration project advanced. One of the most critical parameters for matching observed data was the definition of the top-of-bank elevations along the wetland creekbanks. These elevations define the level at which water starts to overtop the banks and inundate the lower-lying wetland flats.The development of a predictive numerical model of Hexham Swamp wetland has been limited by the availability of accurate topographic data given the dense vegetation covering the majority of the model domain. This has necessitated a pragmatic and incremental approach to wetland restoration in order to manage risk and uncertainty. It is envisaged that topographic data collection will become easier over the next decade or so as the vegetation slowly transitions from its existing tall freshwater reeds to lower profile saltmarsh communities and open water ponds.

Hydrodynamic modeling and characterizing of Lagrangian flows in the West Scott Creek wetlands system, South Carolina

With increased recognition of the value of tidal wetlands and their defining hydrology, the need for better understanding of tidal flow and mixing characteristics is vital to any wetland restoration and enhancement projects and studies. A numerical modeling study was carried out to study the mixing and transport processes in the tide dominated West Scott Creek Estuary, South Carolina. The West Scott Creek estuary is a system of meandering tidal creeks and salt marsh between Edisto Island and the Edisto Beach barrier island. A coupled, depth-integrated hydrodynamic and particle transport model was developed. The model was calibrated and verified against a set of field-measured hydrodynamic data and the model-predicted water elevations, velocities and discharges were in good agreement with the field measurements. The hydrodynamically calibrated model was coupled with a particle tracking module to quantify the residence time distribution and associated transport mechanisms in a spatially varying situation. Computed residence time distribution, under tidal forcing, indicates a strong spatial variation and a non-monotonic distribution along the thalweg of the creek. The model computed a residence time of 4.92 days at the head of the creek. Numerical analysis of the Lagrangian flow field indicated varying mixing regions (strong and weak) within the wetland and the result is anticipated to provide useful information to assess the impact of coastal development in and around the West Scott Creek estuary including the restoration of tidal hydrology.

Registration of ‘St. Bernard’, ‘Las Palomas’, and ‘Lafourche’ Smooth Cordgrass Cultivars

Numerous wetland management and restoration projects utilize smooth cordgrass (Spartina alterniflora Loisel.). Unfortunately, only one released smooth cordgrass cultivar, ‘Vermilion’, is currently available for use in these projects in Louisiana. Three improved smooth cordgrass cultivars, ‘St. Bernard’ (LA12‐101) (Reg. No. CV‐268, PI 665014), ‘Las Palomas’ (LA12‐102) (Reg. No. CV‐269, PI 665015), and ‘Lafourche’ (LA12‐103) (Reg. No. CV‐270, PI 665016), were developed from seeds collected from natural populations in Louisiana and Texas. They are improved, genetically different smooth cordgrass clonal cultivars that were evaluated and compared with Vermilion in replicated field trials for 9 yr in 11 environments. St. Bernard, Las Palomas, and Lafourche recovered more quickly after transplant and produced more viable seeds than Vermilion. The average plant vigor, plant spread, and number of stems per plot for these cultivars were equal to those of Vermilion. DNA fingerprinting data, based on 11 polymorphic microsatellite markers, indicated that St. Bernard, Las Palomas, and Lafourche are genetically different from Vermilion. St. Bernard, Las Palomas, and Lafourche are vigorous, genetically distinct smooth cordgrass cultivars with superior seed set, seed germination, and transplant recovery and therefore are recommended for saline marsh restoration projects in the northern Gulf of Mexico.

Emergy-based evaluation of system sustainability and ecosystem value of a large-scale constructed wetland in North China

Constructed wetland has been widely adopted to deal with degraded natural wetlands and water bodies; thus, more attention should be focused on ecological-economic sustainability and ecological efficiency of these projects for long-term success. Emergy accounting was conducted to investigate the energy and resource flows in constructed wetlands during the restoration process. Emergy-based indexes were adopted to evaluate the sustainability of a pilot large-scale constructed wetland in a large wetland restoration project in North China, carried out to enhance the river water quality and offset the degradation of natural wetland. Emergy and emdollar values for ecosystem services and natural capital were also calculated. The results showed that when outflow was considered as the product, the studied large-scale constructed wetland was more self-supporting and could be operated with lesser financial investment, although the waste treatment efficiency and the sustainability index were lower than conventional small-scale treatment constructed wetlands. Compared with natural wetlands, more visits from tourists and lesser financial investment coming in as feedback into the wetland would reduce system environment loading and promote system self-support ability, ultimately generating sustainability. In addition, the studied large-scale constructed wetland can effectively simulate energy and resource flows of natural wetland ecosystem and contribute a roughly equal value of ecosystem services in term of gross primary production. The studied large-scale constructed wetland can successfully achieve ecosystem functions as replacement for natural wetland and hasten the restoration process, although the restoration effectiveness of ecosystem structures in terms of living biomass and water using emergy-value accounting is still inconclusive.