Vegetation Similarity and Avifaunal Food Value of Restored and Natural Marshes in Northern New York

Measuring the success of wetland restoration efforts requires an assessment of the wetland plant community as it changes following restoration. But analyses of restored wetlands often include plant community data from only one time period. We studied the development of plant communities at 13 restored marshes in northern New York for 4 years, including 1 year prior to restoration and 3 years afterwards. Restored wetlands ranged in size from 0.23 to 1.70 ha. Four reference wetlands of similar basin morphology, soil type, and size (0.29–0.48 ha) that occurred naturally in the same area were studied as comparisons. Dike construction to restore hydrology disturbed the existing vegetation in some parts of the restored sites, and vegetation was monitored in both disturbed and undisturbed areas. Undisturbed areas within the restored sites, which were dominated by upland field grasses before restoration, developed wetland plant communities with lower wetland index values but comparable numbers of wetland plant species than the reference wetlands, and they lagged behind the reference sites in terms of total wetland plant cover. There were significantly more plant species valuable as food sources for wetland birds, and a significantly higher percent cover of these species, at the undisturbed areas of the restored sites than at the reference wetlands. Areas of the restored sites that were disturbed by dike construction, however, often developed dense, monospecific cattail stands. In general, the plant communities at restored sites became increasingly similar to those at the reference wetlands over time, but higher numbers of herbaceous plants developed at the restored sites, including food plants for waterfowl, rails, and songbirds. Differences in shrub cover will probably lessen as natural recolonization increases shrub cover at the restored sites. Natural recolonization appears to be an effective technique for restoring wetlands on abandoned agricultural fields with established plant cover, but it is less successful in areas where soil has been exposed by construction activity.     

Canadian wetlands: Environmental gradients and classification

The Canadian Wetland Classification System is based on manifestations of ecological processes in natural wetland ecosystems. It is hierarchical in structure and designed to allow identification at the broadest levels (class, form, type) by non-experts in different disciplines. The various levels are based on broad physiognomy and hydrology (classes); surface morphology (forms); and vegetation physiognomy (types). For more detailed studies, appropriate characterization and subdivisions can be applied. For ecological studies the wetlands can be further characterized by their chemical environment, each with distinctive indicator species, acidity, alkalinity, and base cation content. For peatlands, both chemical and vegetational differences indicate that the primary division should be acidic, Sphagnum-dominated bogs and poor fens on one hand and circumneutral to alkaline, brown moss-dominated rich fens on the other. Non peat-forming wetlands (marshes, swamps) lack the well developed bryophyte ground layer of the fens and bogs, and are subject to severe seasonal water level fluctuations. The Canadian Wetland Classification System has been successfully used in Arctic, Subarctic, Boreal and Temperate regions of Canada.     

Beaver‐created successional gradients increase β‐diversity of invertebrates by turnover in stream‐wetland complexes

相似文献   

Restoration of vegetation communities of created depressional marshes in Ohio and Colorado (USA): The importance of initial effort for mitigation success

Many studies have attempted to assess the ability of created wetlands to replace the ecological structure and functions of natural wetlands over short time periods (<5 years). Few studies have repeatedly monitored vegetative community development of created depressional wetlands over longer time frames or assessed the return on the level of initial restoration efforts. Here, the vegetation communities of 17 created freshwater marshes in two different geographic regions of the U.S., Ohio and Colorado, ranging from 5 to 19 years old, were monitored over multiple years and compared to natural reference sites. Findings suggest that created marshes in Ohio achieved floristic equivalency with natural reference sites for measures of plant species richness, number of native plant species, number of hydrophytes, and percent plant cover within a decade. Yet, created marshes in Ohio contained double the amount of non-native plant species observed in natural reference sites. In Colorado, created marshes were less successful, failing to achieve floristic equivalency for plant species richness, number of native plant species, and number and percent hydrophytes given more than a decade of restoration. Soil chemistry data suggest that although created marshes achieve certain hydric soil characteristics, they were significantly lower in organic matter, cation exchange capacity, and extractable phosphorus than natural wetlands. Equivalency for soil chemistry will require longer time periods (>14 years). Data suggest that created marshes that seem to be approaching floristic equivalency in early years following construction may level off or even dramatically decline over longer time periods (10–20 years) for certain floristic indicators. Restoration trajectories for Ohio created marshes with strong initial restoration efforts predict floristic equivalency in a median of 14 years compared to 24 years for sites with weak initial efforts. Created marshes with strong initial restoration efforts displayed significantly greater plant species richness, number of native plant species, and number of hydrophytes than sites with low initial efforts, indicating the importance of planting, soil transport and/or contouring in establishing a wetland's restoration trajectory.     

Sustained functional composition of pollinators in restored pastures despite slow functional restoration of plants

Habitat restoration is a key measure to counteract negative impacts on biodiversity from habitat loss and fragmentation. To assess success in restoring not only biodiversity, but also functionality of communities, we should take into account the re‐assembly of species trait composition across taxa. Attaining such functional restoration would depend on the landscape context, vegetation structure, and time since restoration. We assessed how trait composition of plant and pollinator (bee and hoverfly) communities differ between abandoned, restored (formerly abandoned) or continuously grazed (intact) semi‐natural pastures. In restored pastures, we also explored trait composition in relation to landscape context, vegetation structure, and pasture management history. Abandoned pastures differed from intact and restored pastures in trait composition of plant communities, and as expected, had lower abundances of species with traits associated with grazing adaptations. Further, plant trait composition in restored pastures became increasingly similar to that in intact pastures with increasing time since restoration. On the contrary, the trait composition of pollinator communities in both abandoned and restored pastures remained similar to intact pastures. The trait composition for both bees and hoverflies was influenced by flower abundance and, for bees, by connectivity to other intact grasslands in the landscape. The divergent responses across organism groups appeared to be mainly related to the limited dispersal ability and long individual life span in plants, the high mobility of pollinators, and the dependency of semi‐natural habitat for bees. Our results, encompassing restoration effects on trait composition for multiple taxa along a gradient in both time (time since restoration) and space (connectivity), reveal how interacting communities of plants and pollinators are shaped by different trait–environmental relationships. Complete functional restoration of pastures needs for more detailed assessments of both plants dispersal in time and of resources available within pollinator dispersal range.     

Connecting carbon and nitrogen storage in rural wetland soil to groundwater abstraction for urban water supply

We investigated whether groundwater abstraction for urban water supply diminishes the storage of carbon (C), nitrogen (N), and organic matter in the soil of rural wetlands. Wetland soil organic matter (SOM) benefits air and water quality by sequestering large masses of C and N. Yet, the accumulation of wetland SOM depends on soil inundation, so we hypothesized that groundwater abstraction would diminish stocks of SOM, C, and N in wetland soils. Predictions of this hypothesis were tested in two types of subtropical, depressional‐basin wetland: forested swamps and herbaceous‐vegetation marshes. In west‐central Florida, >650 ML groundwater day^?1 are abstracted for use primarily in the Tampa Bay metropolis. At higher abstraction volumes, water tables were lower and wetlands had shorter hydroperiods (less time inundated). In turn, wetlands with shorter hydroperiods had 50–60% less SOM, C, and N per kg soil. In swamps, SOM loss caused soil bulk density to double, so areal soil C and N storage per m² through 30.5 cm depth was diminished by 25–30% in short‐hydroperiod swamps. In herbaceous‐vegetation marshes, short hydroperiods caused a sharper decline in N than in C. Soil organic matter, C, and N pools were not correlated with soil texture or with wetland draining‐reflooding frequency. Many years of shortened hydroperiod were probably required to diminish soil organic matter, C, and N pools by the magnitudes we observed. This diminution might have occurred decades ago, but could be maintained contemporarily by the failure each year of chronically drained soils to retain new organic matter inputs. In sum, our study attributes the contraction of hydroperiod and loss of soil organic matter, C, and N from rural wetlands to groundwater abstraction performed largely for urban water supply, revealing teleconnections between rural ecosystem change and urban resource demand.     

The Impact of Hydrological Restoration on Benthic Aquatic Invertebrate Communities in a New Zealand Wetland

Drainage is a major disturbance affecting wetlands, as drains lower water tables and convert lentic habitats to lotic ones. Consequently, invertebrate communities in drained wetlands are likely to differ from those in unimpacted wetlands. This study investigated the effect of hydrological restoration on invertebrate communities in small drains in a New Zealand fen. Invertebrates were collected over 4 summers from 10 drains within the wetland, one of which was blocked as part of a restoration program. The sampling protocol thus represented a Before‐After Control‐Impact experiment. Invertebrate community composition varied over the 4 years, but variability was greatest in the manipulated drain before and after it was blocked. Relative abundance of the amphipod Paraleptamphopus decreased after blockage, whereas those of the midges Chironomus zelandicus and Tanypodinae increased. Relative abundances of these taxa in control sites were unchanged. Hydraulic restoration thus had a demonstrable impact on the invertebrate communities. The invertebrate community of the blocked drain was compared to that of natural wetlands in undisturbed catchments. Similarity was very low prior to drain blockage, but increased following drain blockage. Invertebrate communities in the restored drain were more similar to those of low pH wetlands than high pH wetlands. Given the goal of restoring the communities to those similar to natural conditions, this was a beneficial result. These results, coupled with studies that showed a decline in the cover of alien pasture grasses around the blocked drain, suggest that drain blockage represents a cost‐effective way of restoring wetland plant and aquatic invertebrate communities, especially where connectivity allows for the natural recruitment of these organisms into restored areas.     

Facilitating the restoration of aquatic plant communities in a Ramsar wetland

Human activities such as land clearing and intensive land use around water bodies, particularly wetlands, have a detrimental impact on water quality and quantity, aquatic plant communities, and associated wetland fauna. Lake Alexandrina and Lake Albert are internationally significant Ramsar wetlands located at the terminus of the Murray River, Australia's longest river system. Agriculture, water regulation, and extraction and droughts have had a detrimental impact on native plant communities in the lakes. We studied the influence of young (<1–3 years) and old (8–11 years) plantings of a native sedge (bulrush), Schoenoplectus tabernaemontani, to facilitate the establishment of aquatic plant communities in comparison with remnant and control sites. We also measured how planting structure (height, stand width, and stem density) changed with age in comparison with remnant sites. Results suggest that as plantings age they get substantially wider and have a greater maximum height, although do not reach similar stand widths by 11 years when compared to remnant areas. However, old plantings do not differ from remnant habitats in relation to aquatic plant species richness, counts of aquatic plants, and community composition. Young plantings have substantially less abundant and diverse plant communities, but are developing on a similar trajectory to old plantings. It is likely that planting sedges along lake shorelines causes a breakwater effect that facilitates the recolonization of wetland plants between the planted area and the water's edge. Management agencies should consider restoring native sedges to increase aquatic biodiversity, and potentially reduce erosion.     

Primary evaluation of carbon sequestration potential of wetlands in China

As one of the important ecosystem services of wetlands, carbon sequestration potential of lakes and swamps in China were investigated. Significant differences were found among the carbon sequestration potential of various lakes, determined by natural conditions and human disturbance. In this study, swamps had a carbon sequestration potential of 4.90 TgC, much higher than lakes in China. Mangrove and coastal marsh have the highest carbon sediment rate among swamps. Carbon sequestration potential in returning farms to lakes and swamps was 30.26 and 0.22 GgC. … a^?1, respectively. Under the ongoing national wetland conservation action plan in China, the carbon sequestration potential of wetland restoration was 6.57 GgC. … a^?1. Protection and restoration measurements can improve carbon sequestration potential of wetlands.     

湿地的国内外研究进展

湿地的国内外研究进展王宪礼李秀珍（中国科学院沈阳应用生态研究所,１１００１５）ＡｄｖａｎｃｅｓｉｎＷｅｔｌａｎｄｓ’Ｒｅｓｅａｒｃｈｅｓ．ＷａｎｇＸｉａｎｌｉ,ＬｉＸｉｕｚｈｅｎ（ＩｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉｅｄＥｃｏｌｏｇｙ,ＣｈｉｎｅｓｅＡ...     

Evaluating Wetland Restoration Success Using Aquatic Macroinvertebrate Assemblages in the Sacramento Valley,California

Currently, there is little professional consensus as to which ecological metrics should be used to measure restoration success in wetlands. Aquatic macroinvertebrate communities have many qualities to recommend them as useful metrics in this manner; yet, they have not been widely used to evaluate wetland restoration success. We examined the macroinvertebrate communities of four restored seasonal wetlands across a chronosequence of postrestoration age and compared them to a remnant natural wetland in the Central Valley of California. We examined two qualitatively different sets of aquatic macroinvertebrate metrics, general measures of community properties (abundance, richness, and diversity) and specific assemblage membership (nonmetric multidimensional scaling and permutational multivariate analysis of variance). Our results using these two different sets of metrics give us different answers. The general measures suggest that wetland macroinvertebrate communities converge on relatively stable values sometime after 10 years postrestoration. The specific assemblage results imply that the particular set of taxa found in restored wetlands is not predictable over the chronosequence we examined. Taken together, our results suggest that aquatic macroinvertebrate communities may be useful for measuring some aspects of restoration success but that there is unlikely to be a final aquatic community pattern indicating restoration success.     

Vegetation communities in continental boreal wetlands along a salinity gradient: Implications for oil sands mining reclamation

Oil sands mining is a major disturbance to boreal landscapes in north-eastern Alberta, Canada. Freshwater peatlands dominate the landscape prior to mining, but the post-mining reclamation landscape will have wetlands that span a salinity gradient. Little is known about the native vegetation communities in subsaline and saline marshes in the boreal region, yet these communities offer the best potential for reclamation of wetlands after oil sands mining. The overall intent of this study is to provide information on natural wetland communities along a gradient of salinities that can be used to enhance oil sands wetland reclamation. Our specific study objectives were to: (1) characterize environmental conditions of industrial and natural wetlands, (2) characterize vegetation communities (composition and diversity) in these wetlands, (3) and explore how vegetation communities (composition and diversity) may be influenced by environmental conditions. We surveyed vegetation communities and environmental variables in 25 natural boreal wetlands along a salinity gradient and in 10 industrial marshes in the oil sands mining region. We observed an electrical conductivity (EC) range of 0.5-28 mS cm⁻¹ in the wetlands, indicating that salinity similar to or higher than anticipated for oil sands reclamation is naturally present in some boreal wetlands. We observed low species richness in both industrial and natural wetlands. There were 101 plant species observed in all the wetlands, with 82 species recorded in the natural wetlands and 44 species in industrial wetlands. At the plot level, richness decreased with increasing EC and pH, but increased with soil organic matter. Using Cluster Analysis and indicator species analysis we defined 16 distinct vegetation community types, each dominated by one or two species of graminoid vegetation. In general these communities resembled those of boreal or prairie marshes. Electrical conductivity, pH, and water depth were important factors correlating with community composition of the wetlands, however peat depth and soil organic content did not differ among community types. Not all community types were present in industrial wetlands, indicating that these communities may need to be planted to enhance overall diversity in future reclaimed oil sands wetlands.     

Restoration of Wetlands from Abandoned Rice Fields for Nutrient Removal, and Biological Community and Landscape Diversity

A number of experimental freshwater wetlands (150 m long × 75 m wide) with different ages since they were abandoned as rice fields, were used to analyze the prospects of multipurpose wetland restoration for such degraded areas. Nitrogen and phosphorus removal rate of the wetlands were determined monthly during the flooding season to estimate their efficiency as filters to remove nutrients from agricultural sewage. The number of wetland birds was recorded regularly to identify their habitat preferences. Both the temporal dynamics and changes in the spatial pattern of land use cover during the last 20 years were determined from aerial photographs and field analysis. All the wetlands appeared to be very efficient in the removal of nitrogen and phosphorus exported from rice fields. Usually 50–98% of the nitrogen and less than 50% of the soluble phosphorus were removed by the wetlands at any stage of restoration. Wetland birds preferred wetlands with intermediate plant cover for resting and sleeping activities better than rice fields and either very open wetlands or very dense ones with tall vegetation. Apart from the improvement in water quality and the restoration of natural habitats, restoration of wetland belts around lagoons will increase spatial heterogeneity and diversity of the landscape.     

克隆植物生长型的研究进展

克隆植物生长型的研究进展陈尚李自珍王刚（国家海洋局第一海洋研究所,青岛２６６００３）（兰州大学,７３００００）ＡｄｖａｎｃｅｓｉｎＲｅｓｅａｒｃｈｅｓｏｆＧｒｏｗｔｈＦｏｒｍｏｆｔｈｅＣｌｏｎａｌＰｌａｎｔ．ＣｈｅｎＳｈａｎｇ（ＦｉｒｓｔＩｎｓｔｉｔ...     

Magellanic Wetlands: More than Moor

Magellanic wetlands in the Patagonian steppe are unique habitats from the point of view of conservation and agriculture. Little is known about their environmental characteristics and plant communities. Our aim was to describe vegetation variability to improve current classifications and reveal environmental factors correlated with vegetation variability in the meadow wetlands (vegas) of southern Chilean Patagonia and Chilean Tierra del Fuego. Five vegetation types resulted from TWINSPAN classification and subsequent interpretation, based on which four new associations were delimited: Magellanic acidic marshes – the Scirpo cernui-Calthetum sagittatae, Magellanic alkaline wet grasslands – the Samolo spathulatae-Azorelletum trifurcatae, Magellanic tall sedge marshes – the Carici maclovianae-Agrostietum stoloniferae, and Magellanic pastures – the Hordeo lechleri-Trifolietum repentis. The fifth vegetation type, saline wetlands, is the rarest and so far the least known community. Magellanic wetland vegetation forms a gradient from short saline marshes to tall graminoid-dominated communities. They reflect a major soil gradient of pH and organic matter content, along with the content of major elements (N, P, K, Fe, Al). Other important factors are ground water regime and grazing intensity.     

Hydrologic similarity to reference wetlands does not lead to similar plant communities in restored wetlands

Few wetland restoration projects include long‐term hydrologic and floristic data collection, limiting our understanding of community assembly over restored hydrologic gradients. Although reference sites are commonly used to evaluate outcomes, it remains unclear whether restoring similar water levels to reference sites also leads to similar plant communities. We evaluated long‐term datasets from reference and restored wetlands 15 years after restoration to test whether similar water levels in reference and restored sites led to vegetation similarity. We compared the hydrologic regimes for three different wetland types, tested whether restored wetland water levels were different from reference water levels, and whether hydrologic similarity between reference and restored wetlands led to similarity in plant species composition. We found restored wetlands had similar water levels to references 15 years after restoration, and that species richness was higher in reference than restored wetlands. Vegetation composition was similar across all wetland types and was weakly correlated to wetland water levels overall. Contrary to our hypothesis, water table depth similarity between restored and reference wetlands did not lead to similar plant species composition. Our results highlight the importance of the initial planting following restoration and the importance of hydrologic monitoring. When the restoration goal is to create a specific wetland type, plant community composition may not be a suitable indicator of restoration progress in all wetland types.     

Coastal vegetation on the Western, Southern, and Eastern coasts of South Korea

We used the Braun-Blanquet method to study the vegetation of coastal wetlands in South Korea. Three habitat types were found, i.e., salt marshes, salt swamps, and sand dunes. These plant communities were classified as: 1) two groups (five associations each) in the salt marshes that comprised either annual herbaceous halophytes (ClassThero-Salicornietea), or biennial/perennial herbaceous species (ClassAsteretea tripolii); 2) one group in the salt swamps consisting of five hydrophilous halo-tolerant associations (ClassPhragmitetea); and 3) three groups in the sand dunes, including one association of annual herbaceous halophytes (ClassSalsoletea komarovii), seven associations of herbaceous perennial halophytes (ClassGlehnietea littoralis), and one association of shrub perennial halophytes (ClassVrticetea rotundifoliae). These three habitat types accounted for the majority of the six main classifications of coastal vegetation distributed in South Korea.     

A synthesis of methane emissions from 71 northern,temperate, and subtropical wetlands

Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database of approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general controls on wetland methane emissions from soil temperature, water table, and vegetation, but also show that these relationships are modified depending on wetland type (bog, fen, or swamp), region (subarctic to temperate), and disturbance. Fen methane flux was more sensitive to vegetation and less sensitive to temperature than bog or swamp fluxes. The optimal water table for methane flux was consistently below the peat surface in bogs, close to the peat surface in poor fens, and above the peat surface in rich fens. However, the largest flux in bogs occurred when dry 30‐day averaged antecedent conditions were followed by wet conditions, while in fens and swamps, the largest flux occurred when both 30‐day averaged antecedent and current conditions were wet. Drained wetlands exhibited distinct characteristics, e.g. the absence of large flux following wet and warm conditions, suggesting that the same functional relationships between methane flux and environmental conditions cannot be used across pristine and disturbed wetlands. Together, our results suggest that water table and temperature are dominant controls on methane flux in pristine bogs and swamps, while other processes, such as vascular transport in pristine fens, have the potential to partially override the effect of these controls in other wetland types. Because wetland types vary in methane emissions and have distinct controls, these ecosystems need to be considered separately to yield reliable estimates of global wetland methane release.     

Vegetation trajectories of restored agricultural wetlands following sediment removal

Recognition of wetland ecosystem services has led to substantial investment in wetland restoration in recent decades. Wetland restorations can be designed to meet numerous goals, among which reestablishing a diverse native wetland plant community is a common aim. In agricultural areas, where previously drained wetland basins can fill with eroded sediment from the surrounding landscape, restoration often includes excavation to expose buried seed banks. The extent to which excavation improves the diversity of wetland plant communities is unclear, particularly in terms of longer‐term outcomes. We examined plant species diversity and community composition in 24 restored agricultural wetlands across west‐central Minnesota, U.S.A. In all study wetlands, hydrology was restored by removing subsurface drainage and plugging drainage ditches, thus reestablishing groundwater connectivity and hydroperiod (“business as usual” treatment). In half of the wetlands, accumulated sediment was removed from the basin and redeposited on the surrounding landscape (“excavated” treatment). Initially, sediment removal significantly decreased invasive species cover, particularly of hybrid cattail (Typha × glauca) and reed canary grass (Phalaris arundinacea), and increased community diversity and evenness. Over time, the effects of sediment removal diminished, and eventually disappeared by approximately 6 years after restoration. While our results demonstrate that sediment removal improves initial restoration outcomes for plant communities, longer‐term benefits require sustained management, such as invasive species control or resetting of basins through additional excavation.     

Pollen and Macro‐Fossil Assemblages in Disturbed Urban Wetlands on South Vancouver Island Reveal Recent Invasion of Reed Canarygrass (Phalaris arundinacea) and Guide Restoration

Paleoecological analyses and historical information were used to characterize pre‐disturbance conditions in Swan Lake wetland of suburban Victoria, Vancouver Island, British Columbia, to provide a reference for restoration and management. Highly invasive reed canarygrass (Phalaris arundinacea) dominates Swan Lake wetlands and inhibits restoration. Grass pollen presumably produced by Phalaris predominates only in the top 5 cm (south site) to 35 cm (north site) of sediment cores. Below these levels assemblages are variously dominated by taxa including Salix, Alnus, Lysichiton, Cyperaceae, and Rosaceae. Pollen grains of agricultural disturbance indicators, such as plantain, liguliflorate Asteraceae, and cereals occur to depths of 35 cm. The results strongly suggest that Phalaris communities arose in historical times following agricultural disturbance and have no pre‐European equivalent. Pollen assemblages below the Phalaris zone, corroborated by historical documentary references, show diverse original wetland types. Disturbance and crop species pollen indicators may be useful indicators of intensity and depth of disturbance. Pre‐agricultural plant communities are a guide for restoration, provided that ecologically limiting factors are managed.