Developing an index of wetland condition from ecological data: An example using HGM functional variables from the Nanticoke watershed,USA

Demand for data on the ecological condition of wetlands is increasing as state and federal management programs recognize its value in reporting on the ambient condition of the resource, targeting restoration and protection efforts, evaluating the effects of mitigation and restoration practices, supporting regulatory decisions, and tracking the impact of land use decisions. We developed an approach for generating a single measure of wetland condition from ecological variables used in hydrogeomorphic (HGM) assessment. An Index of Wetland Condition (IWC) was developed from HGM field data collected to assess freshwater, non-tidal flat, riverine, and depression wetlands in the Nanticoke River watershed. The HGM variables were screened and scored based on a range check, responsiveness, and metric redundancy, employing a method used to develop indices of biotic integrity. Weights of the individual variables were adjusted to reflect our understanding of wetland ecology and to include variables that represented the vegetation, hydrology, and buffer of a wetland. The final IWC score discriminated high, medium, and low site disturbance classes in flat and riverine wetlands and high and low disturbance classes in depressions, one-way ANOVA F-values ranged from 44.5 to 79.1 (all p <0.0001). The combination of the IWC and HGM assessments provides a comprehensive evaluation of the wetland resource. HGM produces information on specific wetland functions. The IWC concisely conveys the ecological condition of the resource and maximizes the utility of the data collected in an HGM assessment.     

Impacts of section 404 permits requiring compensatory mitigation on wetlands in California (USA)

We analyzed data from Section 404 permits issued in California from January 1971 through November 1987 that involved impacts to wetlands and required compensatory mitigation (wetland creation, restoration, or preservation). The purpose of this study was to determine patterns and trends in permitting activity and to document cumulative effects of associated management decisions on the California wetland resource. The 324 permits examined documented that 387 compensatory wetlands (1255.9 ha) were required as mitigation for impacts to 368 wetlands (1176.3 ha). The utility of the data on wetland area was limited, however, since 38.0% of the impacted wetlands and 41.6% of the compensatory wetlands lacked acreage data. The wetland type most frequently impacted (37.8% of impacted wetlands) and used in compensation (38.2% of compensatory wetlands) was palustrine forested wetlands. Estuarine intertidal emergent wetlands had the most area impacted (52.3%) and compensated (62.5%). The majority of the wetlands were small (less than or equal to 4.0 ha in size). Wildlife habitat was the most frequently listed function of impacted wetlands (90.7% of the permits) and objective of compensatory wetlands (83.3%). Endangered species were listed as affected in 20.4% of impacted and 21.0% of compensatory projects. The number of permits requiring compensatory mitigation and the number of impacted and compensatory wetlands increased from 1971 to 1986.Documentation of the details of Section 404 permit decisions was inadequate for the permits we examined. Area information and specific locations of impacted and compensatory wetlands were lacking or of poor quality. Follow-up information was also inadequate. For example, project completion dates were specified in the permit for only 2.2% of compensatory wetlands. Furthermore, less than one-third (31.5%) of the permits required the compensatory wetland to be monitored by at least one site visit. We recommend improved documentation, regular reporting, and increased monitoring for better evaluation of the Section 404 permitting system.     

Arbuscular mycorrhizal fungi enhance spotted knapweed growth across a riparian chronosequence

Arbuscular mycorrhizal fungi (AMF) mediate nutrient uptake that accelerates plant growth and reproduction. Thus, AMF may promote plant invasions often observed along rivers. We assessed the importance of AMF in improving growth of the invasive species, spotted knapweed (Centaurea stoebe), during succession of riparian vegetation along a flood plain in Montana, USA. We grew spotted knapweed with and without AMF in soils collected from riparian sites ranging from 1 to 72 years old and measured the plant’s growth response to AMF. We observed variability in relative effects of AMF, with greatest growth benefits in recently deposited alluvial sediments. We then separated effects of soil and inoculum source by growing spotted knapweed with soils and inocula collected from young or old sites and found that growth responses were greatest in young soils regardless of inoculum source. Our results demonstrate that AMF directly benefit growth of spotted knapweed, especially in soils that typify early successional sites on this alluvial flood plain.     

Aboveground decomposition dynamics in riparian depression and slope wetlands of central Pennsylvania

We examined two types of groundwater-fed wetlands (riparian depressions and slopes) classified using the hydrogeomorphic (HGM) system. These wetland types had previously been shown to differ hydrologically. Our first objective was to determine if HGM was a useful structuring variable when examining aboveground decomposition dynamics (rate of mass loss and rate of nitrogen loss). Our second objective was to determine what soil variables were related to any differences in aboveground decomposition dynamics we might find regardless of HGM subclass. We used the litterbag field bioassay technique, and employed a standard litter type (Phalaris arundinacea) across all wetlands. Our results indicated that HGM would not readily serve as an adequate structuring variable for aboveground decomposition in riparian depressions and slope wetlands of central Pennsylvania. Discriminant analysis and classification and regression tree (CART) modeling found soil cation exchange capacity, soil pH, soil organic matter, and soil % nitrogen to be potentially important soil variables related to mass loss, and soil % nitrogen and soil pH to be potentially important variables related to nitrogen loss rate.     

The importance of seasonal flow timing for riparian vegetation dynamics: a systematic review using causal criteria analysis

1. Whilst it is widely recognised that a natural flow regime is important for sustaining riverine ecosystems, the relative importance of the various components of flow regime for riparian vegetation dynamics is poorly understood. We sought to determine the current extent of knowledge on the importance of seasonal flow timing for riparian plants by conducting a systematic review of the literature using causal criteria analysis. 2. Using a definition of ‘riparian’ that included riverine, wetland and floodplain systems, we found sufficient evidence to provide strong support for the existence of causal relations between seasonal flow timing and a number of riparian plant processes, namely rates of waterborne dispersal (hydrochory), germination and growth, as well as riparian community composition. There was insufficient evidence to infer a causal relationship between flow timing and the reproduction or survival of riparian plants. 3. Thus, we argue that seasonal flow timing is important for many of the processes that generate and sustain riparian vegetation communities. River regulation, and/or flow management aimed at restoring ecological values, should consider flow timing and its implication for riparian flora. Because of regulation, many of the rivers of south‐eastern Australia have inverted seasonal flow patterns. Whilst direct evidence of the effects of this inversion on the flora of these rivers is lacking, the results of our causal analysis allow us to predict how these plant communities may have been affected. 4. However, these predictions must be treated with caution because of the reliance of some of the causal analyses on wetland studies. For riverine flora, further research is particularly needed on the effects of seasonal flow timing on hydrochory, survival and reproduction. 5. Causal criteria analysis provides a defensible and efficient means for assessing the extent of evidence for or against ecological hypotheses of this kind. In this case, systematic review of the literature provided strong evidence to support a number of causal links between seasonal flow timing and riparian vegetation dynamics, whilst also efficiently identifying knowledge gaps.     

Long-term development of tidal mitigation wetlands in Florida

Monitoring periods for compensatory wetland mitigation projects are relatively short, typically 3 to 5 years. Although forested wetlands may require decades to develop structural characteristics similar to those of natural systems, studies that describe long-term trends in site development are rare. Eighteen mitigation sites in Florida that had originally been sampled in 1988 were re-visited in 2005. Changes in mangrove community composition and stand structure occurring over this timeframe at ten of these sites are described and compared with other mangrove wetlands in Florida. Factors limiting development of the remaining sites are discussed. The continued persistence and development of the majority of these mitigation sites indicates that the mitigation process can be successful, at least in terms of compliance with the typical permit requirements. Basal area and height had increased at most sites, and some were difficult to visually distinguish from adjacent natural stands of mangroves. However, even after 13–25 years, stand structure in mangrove mitigation wetlands in Florida still differed from that of natural sites. Although the number of mangrove species was similar, mitigation sites had lower basal area and height than natural sites, and were more dense and complex than natural sites.     

The boundaries of river systems: the metazoan perspective

1. This overview of metazoans associated with the riparian/groundwater interface focuses on the fauna inhabiting substratum interstices within the stream bed and in alluvial aquifers beneath the floodplain. The objective is to integrate knowledge of habitat conditions and ecology of the interstitial fauna into a broad spatiotemporal perspective of lotic ecosystems. 2. Most aquatic metazoans of terrestrial ancestry, secondarily aquatic forms including insects and water mites (Hydracarina), are largely confined to surface waters (epigean), most of the time penetrating only the superficial interstices of the stream bed. 3. Primary aquatic metazoans include crustaceans and other groups whose entire evolutionary histories took place in water. Some species are epigean, whereas other members of the primary aquatic fauna are true subterranean forms (hypogean ) , residing deep within the stream bed and in alluvial aquifers some distance laterally from the channel. 4. The hypogean/epigean affinities of interstitial animals are reflected in repetitive gradients of species distribution patterns along vertical (depth within the stream bed), longitudinal (riffle/pool), and lateral (across the floodplain) spatial dimensions, as well as along recovery trajectories following floods (temporal dimension). 5. Fluvial dynamics and sediment characteristics interact to determine hydraulic conductivity, oxygen levels, pore space, particle size heterogeneity, organic content and other habitat conditions within the interstitial milieu. 6. Multidimensional environmental gradients occur at various scales across riparian/groundwater boundary zones. The spatiotemporal variability of hydrogeomorphological processes plays an important role in determining habitat heterogeneity, habitat stability, and connectivity between habitat patches, thereby structuring biodiversity patterns across the riverine landscape. 7. The erosive action of flooding maintains a diversity of hydrarch and riparian successional stages in alluvial floodplains. The patchy distribution patterns of interstitial communities at the floodplain scale reflect, in part, the spatial heterogeneity engendered by successional processes. 8. Interstitial metazoans engage in passive and active movements between surface waters and ground waters, between aquatic and riparian habitats, and between different habitat types within the lotic system. Some of these are extensive migrations that involve significant exchange of organic matter and energy between ecosystem compartments. 9. The generally high resilience of lotic ecosystems to disturbance is attributable, in part, to high spatiotemporal heterogeneity. Habitat patches less affected by a particular perturbation may serve as ’refugia ‘; from which survivors recolonize more severely affected areas. Mechanisms of refugium use may also occur within habitats, as, for example, through ontogenetic shifts in microhabitat use. Rigorous investigations of interstitial habitats as refugia should lead to a clearer understanding of the roles of disturbance and stochasticity in lotic ecosystems. 10. Development of realistic ’whole river ‘; food webs have been constrained by the exclusion of interstitial metazoans, which may in fact contribute the majority of energy flow in lotic ecosystems. A related problem is failure to include groundwater/riparian habitats as integral components of alluvial rivers. A conceptual model is presented that integrates groundwater and riparian systems into riverine food webs and that reflects the spatiotemporal complexity of the physical system and connectivity between different components. 11. Interstitial metazoans also serve as ’ecosystem engineers, ‘; by influencing the availability of resouces to other species and by modifying habitat conditions within the sediment. For example, by grazing on biofilm, interstitial animals may markedly stimulate bacterial growth rates and nutrient dynamics. 12. Although there has been a recent surge of interest in the role of interstitial animals in running waters, the knowledge gaps are vast. For example, basic environmental requirements of the majority of groundwater metazoans remain uninvestigated. Virtually nothing is known regarding the role of biotic interactions in structuring faunal distribution patterns across groundwater/riparian boundary zones. Interstitial metazoans may contribute significantly to the total productivity and energy flow of the biosphere, but such data are not available. Nor are sufficient data available to determine the contribution of groundwater animals to estimates of global biodiversity. 13. Effective ecosystem management must include groundwater/riparian ecotones and interstitial metazoans in monitoring and restoration efforts. Evidence suggests that a ’connected ‘; groundwater/riparian system provides natural pollution control, prevents clogging of sediment interstices and maintains high levels of habitat heterogeneity and successional stage diversity. River protection and restoration should maintain or re-establish at least a portion of the natural fluvial dynamics that sustains the ecological integrity of the entire riverine–floodplain–aquifer ecosystem. Keywords: groundwater/riparian ecotones, hyporheic habitat, epigean, hypogean, interstitial fauna, biodiversity, food webs     

Variation in wetland invertebrate communities in lowland acidic fens and swamps

1. Invertebrates were collected semi‐quantitatively from four relatively undisturbed wetlands in the west coast of New Zealand’s South Island: two acidic fens and two swamps. Samples were collected from up to four discrete habitats within each wetland: large open‐water channels, small leads (small, ill‐defined channels with emergent vegetation in them) and large (>10 m diameter) or small (<10 m diameter) ponds. Samples were also collected from different plant species within each wetland, each with different morphology, and from areas without vegetation. This was done to determine whether invertebrate communities varied more between‐wetlands than within‐wetlands, as the results had implications for future wetland monitoring programmes. 2. Principal components analysis of water chemistry data revealed striking differences in pH, conductivity and nutrients between the four wetlands. Not surprisingly, pH was lowest in one of the acidic fens, and highest in one of the swamps, where conductivity was also high. Midges (Tanytarsus, Tanypodinae, Orthocladiinae and Ceratopogonidae), nematodes, harpactacoid copepods and the damselfly Xanthocnemis dominated the invertebrate fauna. Orthoclad midges and mites were the most widespread taxa, found in 91 of 94 samples. Diptera were the most diverse invertebrate group, followed by Trichoptera and Crustacea. 3. Ordination analysis of the invertebrate data showed that the four wetlands supported different invertebrate communities. However, species composition did not change completely along the ordination axes, suggesting that a relatively species‐poor invertebrate fauna was found in the wetlands. Taxa such as molluscs were restricted to wetlands with high pH. Multi‐response permutation procedures (MRPP) was used to analyse resultant ordination scores to see how they differed according to five terms: ‘Wetland’, ‘Habitat’, ‘Growth Form’, ‘Morphology’ and ‘Plant’. Most of the sample separation along ordination axes reflected differences between wetland, although the ‘Habitat’ and ‘Plant’ terms also explained some of the variation. The ‘Growth Form’ and ‘Morphology’ terms had only minor effects on community composition. 4. A multivariate regression tree modelled invertebrate assemblages according to the five predictor terms. The resultant model explained 54.8% of the species variance. The ‘Wetland’ term contributed most to the explanatory power, followed by ‘Habitat’. ‘Growth type’ and ‘Morphology’ explained only a small amount of variance to the regression tree, while the different plant species explained none of the variation. 5. Variation in these New Zealand wetland invertebrate communities appears to be controlled most by large‐scale factors operating at the level of individual wetlands, although different habitats within individual wetlands contributed slightly to this variation. Based on these results, sampling programmes to describe wetland invertebrate communities do not need to sample specific habitats or plant types within a wetland. Instead, samples can be collected from a wide range of habitats within individual wetlands, and pooled. Within each habitat, it is unnecessary to collect individual samples from different macrophytes or un‐vegetated areas. Our results suggest that collecting replicate pooled samples from different habitats within each wetland will be sufficient to characterize the invertebrate assemblage of each wetland.     

A multi-criteria,ecosystem-service value method used to assess catchment suitability for potential wetland reconstruction in Denmark

Wetlands provide a range of ecosystem services such as drought resistance, flood resistance, nutrient deposition, biodiversity, etc. This study presents a new multi-criteria, ecosystems service value-driven method to drive the optimal placement of restored wetlands in terms of maximizing selected ecosystem services which a wetland can provide or affect. We aim to answer two questions: 1) which of the ecosystem services indicators defines the placement of wetlands today? 2) Based on the ecosystem services indicator assessment, what are the recommendations for future selection of catchments for potential wetland reconstruction (i.e. restoration)?Five key ecosystem services indicators produced or affected by wetlands in Denmark were mapped (recreational potential, biodiversity, nitrogen mitigation potential, inverse land rent, and flash-flood risk). These services were compared to current placements of wetlands. Furthermore, scenario testing and hotspot analysis were combined to provide future recommendations for optimal placements of wetlands. The scenarios investigated were Climate Adaptation and Protection of Aquatic Environment, Land-Based Economy, and Rich Nature. Based on these scenarios, the most suitable areas for wetland reconstruction were mapped, taking both the scenarios and attached weightings of ecosystem services indicators into account.According to statistical results current reconstructed wetlands are situated in catchments with lower biodiversity, higher nitrogen mitigation potential, higher land rent (i.e. agricultural intensive areas), and to some extent higher flash flood risk compared to the median of catchments with wetlands. Hence, recreation potential, high biodiversity, and low land rent has not been prioritized. 35 out of the 3023 catchments investigated were identified with an especially high suitability when optimizing all scenarios. This coincides with a high suitability around peri-urban and urban areas and near natural areas, hence capturing both supply and demand services. Of the 35 identified catchments with potentially high suitability, only 2 actually hold a presently reconstructed wetland. This indicates a prior placement with almost no consideration of maximizing ecosystem services benefits.We recommend a systematic approach, such as the ecosystem service value-driven method demonstrated in the present case study, to target more services and improve the overall benefit from wetlands. This approach seeks to inform decision makers of synergies in the landscape, which is likely to transcend future policy implementations.     

Aquatic macroinvertebrate assemblages in mitigated and natural wetlands

Many wetlands have been constructed in West Virginia as mitigation for a variety of human disturbances, but no comprehensive evaluation on their success has been conducted. Macroinvertebrates are extremely valuable components of functioning wetland ecosystems. As such, benthic and water column invertebrate communities were chosen as surrogates for wetland function in the evaluation of 11 mitigation and 4 reference wetlands in West Virginia. Mitigation wetlands ranged in age from 4 to 21 years old. Overall familial richness, diversity, density and biomass were similar between mitigation and reference wetlands (p > 0.05). Within open water habitats, total benthic invertebrate density was higher in reference wetlands, but mass of common taxa from water column samples was higher in mitigation wetlands (p < 0.05) Planorbidae density from benthic samples in emergent habitats was higher in reference than mitigated wetlands. Benthic Oligochaeta density was higher across open water habitats in mitigation wetlands. All other benthic taxa were similar between wetland types. Among the most common water column orders, Isopoda density was higher in reference wetlands, but Physidae density was higher in mitigation wetlands. Within mitigation wetlands, emergent areas contained higher richness and diversity than open areas. These data indicate that mitigation and reference wetlands generally support similar invertebrate assemblages, especially among benthic populations. The few observed differences are likely attributable to differences in vegetative community composition and structure. Mitigation wetlands currently support abundant and productive invertebrate communities, and as such, provide quality habitat for wetland dependent wildlife species, especially waterbirds and anurans.     

Comparing tiers of a multi-tiered wetland assessment in the Prairie Pothole Region

Wetland assessment has been shown to be an important tool in understanding the condition and function of the world’s wetlands, and use of muli-tiered assessment strategy has been recommended. In order to evaluate the performance of each tier of a multi-tiered wetland assessment strategy, we sampled 255 seasonally-ponded wetlands in the Missouri Coteau, the most wetland dense ecoregion in the Prairie Pothole Region. We assessed the condition of each study wetland using four sampling methods and models (tiers) of increasing levels of effort and complexity: (1) a level 1 assessment using the geographic information system-based Landscape Wetland Condition Analysis Model (LWCAM); (2) a level 2 assessment using the North Dakota Rapid Assessment Method (NDRAM); (3) a level 3- assessment using the vegetative-based Floristic Quality Index (FQI) and (4) a level 3 assessment consisting of a Hydrogeomorphic (HGM) Model functional assessment. We compared assessment tiers to determine how similar the different levels of assessment ranked sites either by condition or function. Both the NDRAM and FQI assessments, though very different in wetland characteristics assessed, provided similar condition rankings as the more intensive level 3 HGM assessment (89 and 90% similar, respectively). Additionally, the FQI was 86% similar to the level 2 NDRAM, indicating that these two assessment methods have utility in assessing wetlands similar to a HGM assessment. Information from this study can be used as a tool for determining need specific, financial, and time appropriate wetland sampling methods.     

170 Wetland Diatom Assemblages as Indicators of Flooding Influence and Surrounding Landuse in the Willamette Valley,OR

The objective of this study was to examine the influences of the adjacent river and surrounding landuse on wetland diatom distributional patterns. Diatoms were identified in surface sediment samples from 35 riverine‐impounded wetlands within the Willamette Valley, OR. A total of 221 species were identified and no single species dominated the assemblage at all sites. Diatom richness was high throughout the area (median 71, range 66–75). The Araphidineae:Centrales index, a measure of periphytic to planktonic species ratio, was lowest at sites within the river's annual floodplain zone. A low A:C index is to be expected at wetlands that receive inputs of river planktonic species through regular flooding by adjacent large rivers. Surrounding landuse can confound the influence of riverine flooding on wetland diatom assemblages by influencing water quality. Relative abundance of the two most common species, Aulacoseira crenulata and Fragilaria capusina related negatively to % agricultural landuse surrounding the wetland. These results indicate that riverine wetland diatom assemblages may be influenced by flooding from adjacent rivers and surrounding landuse and therefore wetland sediment diatoms might serve as useful indicators of both historical environmental changes in nearby large rivers and surrounding watersheds.     

Efficacy of the hydrogeomorphic model (HGM): A case study from western Tennessee

Hydrogeomorphic models (HGM) for wetland classification and functional assessment have been developed for several regions in the United States. However, validation of models is lacking, even though models are already in use and the general idea is that each is a working model, developing over time with new ideas and information. We examined the HGM developed for western Tennessee using novel data collected from six stream systems, two channelized, two channelized and leveed, and two unchannelized. The western Tennessee HGM has the ability to differentiate altered and unaltered rivers based mainly on changes to hydrologic floodplain functions, although functional capacity index values were validated from independent measures. Effects of channelization were confounded in western Tennessee by other disturbances, channel recovery processes, and variability due to levee construction. Levees render the greatest change to floodplains as they disconnect the channel and floodplain system, decreasing water tables and possible exchanges. One of the main factors controlling productivity along channels without levees was sedimentation. We recommend that estimated rates of sedimentation be incorporated into an updated version of the HGM. Variability of human alterations and natural floodplain heterogeneity suggest landscape factors (e.g., beta diversity, degree of ponding) and use of gradient indices may result in greater resolution for determining functional capacity of low gradient, riverine systems.     

Development of community metrics to evaluate recovery of Minnesota wetlands

Monitoring wetland recovery requires assessment tools that efficiently and reliably discern ecosystem changes in response to changes in land use. The biological indicator approach pioneered for rivers and streams that uses changes in species assemblages to interpret degradation levels may be a promising monitoring approach for wetlands. We explored how well metrics based on species assemblages related to land use patterns for eight kinds of wetlands in Minnesota. We evaluated land use on site and within 500 m,1000 m, 2500 m and 5000 m of riverine, littoral, and depressional wetlands (n = 116) in three ecoregions. Proportion of agriculture, urban, grassland, forest,and water were correlated with metrics developed from plant, bird, fish, invertebrate, and amphibian community data collected from field surveys. We found79 metrics that relate to land use, including five that may be useful for many wetlands: proportion of wetland birds, wetland bird richness, proportion of insectivorous birds, importance of Carex, importance of invasive perennials. Since very few metrics were significant for even one-half of the wetland types surveyed, our data suggest that monitoring recovery in wetlands with community indicators will likely require different metrics,depending on type and ecoregion. In addition, wetlands within extensively degraded ecoregions may be most problematic for indicator development because biotic degradation is historic and severe. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparison of Soil Organic Matter in Created, Restored and Paired Natural Wetlands in North Carolina

Soil organic matter (SOM) content is a key indicator of soil quality and is correlated to a number of important soil processes that occur in wetlands such as respiration, denitrification, and phosphorus sorption. To better understand the differences in the SOM content of created (CW), restored (RW), and paired natural wetlands (NWs), 11 CW/RW-NW pairs were sampled in North Carolina. The site pairs spanned a range of hydrogeomorphic (HGM) subclasses common in the Coastal Plain. The following null hypotheses were tested: (1) SOM content of paired CW/RWs and NWs are similar; (2) SOM content of wetlands across different HGM subclasses is similar; and (3) interactions between wetland status (CW/RW vs. NW) and hydrogeomorphic subclass are similar. The first null hypothesis was rejected as CW/RWs had significantly lower mean SOM (11.8 ± 3.9%) than their paired NWs (28.98 ± 8.0%) on average and at 10 out of the 11 individual sites. The second and third null hypotheses were also rejected as CW/RWs and NWs in the non-riverine organic soil flat subclass had significantly higher mean SOM content (31.08 ± 14.2%) than the other three subclasses (8.18 ± 2.5, 11.18 ± 8.2, and 10.38 ± 4.2%). Individual sites within this fourth subclass also had significantly different SOM content. This indicated that it would be inappropriate to include the organic soil flat subclass with either the riverine or non-riverine mineral soil flat subclasses when considering restoration guidelines. These results also suggested that if there is a choice in mitigation options between restoration or creation, wetlands should be restored rather than created, especially those in the non-riverine organic soil flat subclass.     

171 Light-Induced Growth of Winter Phytoplankton Collected from the Benthic Boundary Layer in Coastal Oregon Waters

The objective of this study was to examine the influences of the adjacent river and surrounding landuse on wetland diatom distributional patterns. Diatoms were identified in surface sediment samples from 35 riverine-impounded wetlands within the Willamette Valley, OR. A total of 221 species were identified and no single species dominated the assemblage at all sites. Diatom richness was high throughout the area (median 71, range 66–75). The Araphidineae:Centrales index, a measure of periphytic to planktonic species ratio, was lowest at sites within the river's annual floodplain zone. A low A:C index is to be expected at wetlands that receive inputs of river planktonic species through regular flooding by adjacent large rivers. Surrounding landuse can confound the influence of riverine flooding on wetland diatom assemblages by influencing water quality. Relative abundance of the two most common species, Aulacoseira crenulata and Fragilaria capusina related negatively to % agricultural landuse surrounding the wetland. These results indicate that riverine wetland diatom assemblages may be influenced by flooding from adjacent rivers and surrounding landuse and therefore wetland sediment diatoms might serve as useful indicators of both historical environmental changes in nearby large rivers and surrounding watersheds.     

Consideration of Geography and Wetland Geomorphic Type in the Development of Great Lakes Coastal Wetland Bird Indicators

We examined how geographic distribution of birds and their affinities to three geomorphic wetland types would affect the scale at which we developed indicators based on breeding bird communities for Great Lakes coastal wetlands. We completed 385 breeding bird surveys on 222 wetlands in the US portion of the basin in 2002 and 2003. Analyses showed that wetlands within two ecoprovinces (Laurentian Mixed Forest and Eastern Broadleaf Forest) had different bird communities. Bird communities were also significantly different among five lakes (Superior, Michigan, Huron, Erie, and Ontario) and among three wetland types (lacustrine, riverine, barrier-protected). Indicator values illustrated bird species with high affinities for each group (ecoprovince, lake, wetland type). Species with restricted geographic ranges, such as Alder and Willow Flycatchers (Empidonax alnorum and E. traillii), had significant affinities for ecoprovince. Ten bird species had significant affinities for lacustrine wetlands. Analyses on avian guild metrics showed that Lake Ontario wetlands had fewer long-distant migrants and warblers than other lakes. Numbers of short-distant migrants and total individuals in wetlands were higher in the Eastern Broadleaf Forest ecoprovince. Number of flycatchers and wetland obligate birds were not different among provinces, lakes, or wetland type. One potential indicator for wetland condition in Great Lakes wetlands, proportion of obligate wetland birds, responded negatively to proportion of developed land within 1 km of the wetland. We conclude that, although a guild approach to indicator development ameliorates species-specific geographic differences in distribution, individual species responses to disturbance scale will need to be considered in future indicator development with this approach.     

Assessing the value of wetlands to waterbirds: exploring a population-based index at flyway and regional levels

Traditionally, species richness, species diversity, total count, biomass, energy consumption and the Ramsar ‘1% threshold’ have been used to assess the importance of wetlands for waterbirds. Designation of wetlands of international importance (Ramsar sites) based on waterbirds has focused on those species meeting the Ramsar 1% population threshold levels. These levels prioritise a subset of species as being important, with little or no consideration to the contributions of the remaining species’ populations. In this paper, we evaluate and further describe a quantitative method to assess wetland avifaunal importance. Termed the Waterbird Conservation Value (WCV), this index sums the ratio of each species’ abundance to its published 1% threshold across all species to give an overall measure of the ‘value’ of the waterbirds at a wetland. Large values indicate that large proportions of the total populations of waterbird species are present at the wetland. Indices can be evaluated at site and species levels. The WCV is a more nuanced approach, sensitive to actual species’ abundance rather than counts of ‘1% threshold’ species and considers all species in the assessment. The outputs of the WCV index are demonstrated and discussed using a case study from three regions within the East Atlantic flyway.     

大兴安岭北部多年冻土区河岸森林湿地土壤性质和微生物呼吸活性特征

多年冻土区河岸森林湿地是水文、生态和生物化学过程的关键区域。本研究以河岸森林湿地及其与泥炭地的交错带土壤为对象,分析了腐殖质层和不同深度土壤理化性质、生态化学计量和微生物呼吸活性( 微生物生物量碳、基础呼吸、微生物熵和代谢熵)特征。结果表明: 与大兴安岭多年冻土区泥炭地和河岸森林湿地的交错带相比,河岸森林湿地土壤理化性质主要分异在20 cm土层以下,其总碳、总氮含量和碳磷比、氮磷比显著降低,生态化学计量特征的变化主要是由于氮含量变化引起的,说明河岸森林湿地土壤氮转移相对较快,存在氮限制;交错带湿地土壤中钠、镁、钾和钙含量主要在30 cm土层发生分异,而河岸森林湿地土壤中钠、镁、钾和钙含量主要在20 cm土层发生分异,其镁含量与土壤总碳、总氮和总磷含量显著相关,说明土壤镁含量是大兴安岭河岸森林湿地的重要营养元素;河岸森林湿地和交错带腐殖质层微生物呼吸活性高于其他层土壤,说明其易分解的碳组分含量高;河岸森林湿地和交错带土壤微生物呼吸活性与土壤理化性质、生态化学计量特征及营养元素的相关性存在差异,而河岸森林湿地土壤总氮含量与微生物呼吸活性显著相关,说明大兴安岭河岸带湿地土壤微生物活性受氮的限制。     

大型人工湿地生态可持续性评价

大型人工湿地现已广泛应用于湖滨带、河滨带水质净化及湿地生态修复,这些人工湿地的生态可持续性评价对于其科学管理调控及长期可持续运行具有重要意义。运用综合指标评价及层次分析法,根据人工湿地生态系统的特点,提出并建立了适合评价人工湿地可持续性运行的指标体系,建立的评价指标包括生态特征与功能、水质净化功能及经济社会功能三项一级指标,及对应的14个二级指标。运用建立的评价指标体系对南四湖湖滨带新薛河大型人工湿地示范工程的生态可持续性运行了评价,评价结果显示:植物多样性、氨氮去除能力、生物入侵抵抗力、野生动物栖息地、COD去除能力是影响大型人工湿地运行效果的主要制约因素;新薛河人工湿地生态可持续性综合指数为0.6862,处于"良"级,其中生态特征功能可持续性指数最高,为0.7732;水质净化功能和社会经济功能指数分别为0.6190,0.6492。由结果可知,南四湖新薛河大型人工湿地具有重要的生态修复功能,水质净化功能方面应加强植物定期收割及植被管理,同时经济社会功能还有待加强,植物经济效益及旅游娱乐效益还有待深入开发。建立的人工湿地可持续性运行的评价指标体系具有较强的针对性,可用于其他大型人工湿地的生态可持续性评价。