Floristic quality as an indicator of human disturbance in forested wetlands of northern New England

Across the country, degradation of freshwater wetlands has prompted a need for science-based methods for assessing and monitoring wetland condition. Floristic Quality Assessment (FQA) is an assessment that measures the health of an ecosystem. FQA is based on resilience values called Coefficients of Conservatism (C-values), preassigned to each plant species. The method has proven to signal human disturbance in most wetland types, but is understudied in forested wetlands. We compared FQA scores and Ecological Integrity Assessment (EIA) scores (Level 2) of 11 red maple − Sphagnum basin swamps (RMSBS) of New Hampshire and 12 red maple swamps (RMS) of southern Maine to test the hypothesis that FQA signals human disturbance in forested wetlands. EIA did not distinguish RMSMS from RMS, however Mean C, Cover Weighted Mean C (wC), and FQI did. In RMSBS, wC showed the strongest positive correlation with EIA scores. In RMS, Mean C showed the strongest positive correlation with EIA scores. For all sites combined, wC and Mean C were significantly correlated with EIA scores. Meaningful relationships were not observed between FQI or wFQI and EIA scores. The results indicate that Mean C and wC offer a reliable metrics for the evaluation of forested wetlands in northern New England.     

Wetland ecosystem comparison using a suite of plant assessment measures

In light of extensive human impact on wetlands it is necessary that we develop an effective way to monitor the effects of impact in order to prevent further destruction. One method is plant community assessment, specifically Floristic Quality Assessment (FQA), which is common, but can be subjective. In this case study, we implement FQA, as well as specific morphological and chemical assessment measures over a two-year period in order to compare two wetlands in the Lake George watershed in the Adirondack mountains and their response to human impact. While the wetlands studied demonstrated very different water chemistry profiles makeups, FQA did not reveal substantial differences between plant communities. However, more specific analyses of plant morphology and tissue chemistry did reveal significant differences that reflected the level of impact at these two sites. Namely, the simple plant Lemna minor had consistently shorter roots and Nuphar lutea contained higher amounts of nitrogen in above ground tissues when growing in an anthropogenically impacted wetland. We suggest that FQA and specific plant morphology and tissue chemistry measurements be performed concurrently to provide indication of both long- and short-term effects of human impact in wetland ecosystems.     

运用植物区系质量指数快速评估湿地植被恢复成效

目前通常采用的评估湿地保护和恢复成效的指标体系较为复杂, 常涉及生物学、环境科学和社会学等多个学科, 导致监测评估成本高, 并难以实现综合的定量评估, 因此有必要提出能够在较大程度上表达生态环境状况的综合生态指标。植物区系质量指数(Floristic Quality Assessment Index, FQAI)反映了植物区系中物种的生态保守性程度, 作者将其作为主要生态指标, 来验证该指标用于湿地植被恢复成效定量评估的有效性。作者以四川盆地丘陵和平原地区湿地植物为对象, 构建了区域库塘及河滩湿地植物区系质量指数计算方法与赋值表, 以成都市重要水源地——云桥湿地的3年生态恢复成效为案例进行了检验。结果表明, 在云桥湿地3年恢复期间, 植物物种组成及其比例在恢复年限间无显著差异, Shannon-Wiener指数、Pielou指数和Simpson指数在3年中也并未发生显著变化, 但生态保守性系数平均值(CC_mean)和植物区系质量指数(FQAI)均随恢复年限显著上升, 表明FQAI可以快速、有效地实现生态系统水平湿地植被恢复成效的比较和定量评估。     

Adult Odonata conservatism as an indicator of freshwater wetland condition

There is a growing need to identify effective and efficient biological indicators for wetland assessment, and adult damselflies and dragonflies (Insecta: Odonata) possess several attributes that make them attractive for this application. We introduce a general indicator of freshwater wetland condition based on objectively estimated adult Odonata species conservatism, or sensitivity to human disturbances. We used an extensive opportunistic survey dataset from Rhode Island (USA) to empirically assign a coefficient of conservatism (CoC) to each of 135 Odonata species, based on their exclusivity to categories of degradation among 510 wetlands; the mean CoC of species observed in the adult stage was applied as an index of wetland integrity. An independent sample of 51 wetlands was also drawn from the opportunistic survey to test the performance of the index relative to human disturbance, as measured by multimetric rapid assessment and surrounding impervious surface area. The index was well predicted by both disturbance measures and showed no evidence of dependence on sampling effort, wetland size, or geomorphic class. Our findings suggest that conservatism of adult Odonata averaged across species may provide a robust indicator of freshwater wetland condition. And because adult Odonata are generally easy to identify, especially relative to larval Odonata, the index could be particularly useful for wetland assessment. Our straightforward empirical approach to CoC estimation could be applied to other existing spatially referenced Odonata datasets or to other species assemblages.     

Relationship between the natural abundance of soil nitrogen isotopes and condition in North Dakota wetlands

A statewide condition assessment of North Dakota wetlands in the summer of 2011 was conducted as part of the U.S. Environmental Protection Agency's National Wetland Condition Assessment (NWCA). Two other wetland condition assessments, the Index of Plant Community Integrity (IPCI) and North Dakota Rapid Assessment Method (NDRAM), were also completed at each wetland. Previous studies have identified how the distinct signatures of stable isotopes can be used to determine different land uses, anthropogenic impacts, nutrient cycling, and biological processes. To evaluate if these relationships existed in northern prairie wetlands, the data collected from the wetland assessments were compared with the natural abundance of soil nitrogen (δ¹⁵N) isotopes. Wetland soil δ¹⁵N was significantly higher (isotopically heavier) in wetlands surrounded by cropland compared to those surrounded by idle or grazed/hayed grasslands, possibly reflecting anthropogenic impacts and multiple nitrogen sources. Soil δ¹⁵N was significantly correlated with floristic quality, IPCI scores, NDRAM scores, and average buffer width, indicating that soil δ¹⁵N values may be representative of wetland condition. Soil δ¹⁵N exhibited significant differences among wetland types, although limited sample sizes of certain wetland types may have affected this result. Additional studies on the natural abundance of wetland soil isotopes need to be performed in northern prairie wetlands. This study is the first step in exploring the potential applications of wetland soil nitrogen isotopes regarding wetland assessment and surrounding land use and provides important insight for future studies.     

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.     

A novel method for floristic quality assessment using the vegetation of the Jiuding Mountain, Sichuan, China as an example

Floristic Quality Assessment (FQA) is proposed as a new method to assess floristic integrity. In the present study, we use both the conventional method broadly adopted in the USA and a new one proposed herein to assess the floristic quality of the Jiuding Mountain. For the application of the FQA, each plant species was assigned an integer from 0 to 10 termed coefficient of conservatism (C) based on its global distribution area. The coefficient shows the degree of fidelity of each plant species to the flora of the west slope of the Jiuding Mountain and represents a rank based on its distribution area. Those species receiving a C value of 0–1 are distributed all over the world, those receiving a C value of 2–3 mostly in tropical areas, and those receiving a C value of 4–6 broadly in temperate areas. Species with C values of 7–8 are endemic to China and those with coefficients 9–10 are restricted to the Hengduan Mountains or even endemic to the Jiuding Mountain. Based on the fact that different plant species show different relative importance values (IV), the new method estimates the weighted averages for the coefficient of conservatism called the weighted mean coefficient of conservatism (     _w). The floristic quality index (FQI) was then derived from     or     _w, native species richness (N) and non-native species (A). As expected when using the new method, the dominant species of the communities obtained different Cs, which resulted in different     _ws and FQI_ws as compared to the conventional method.     

中国不同地区滨海湿地植物区系的性质及类似关系

滨海湿地是地球上脆弱的自然生态系统和重要的生物景观成分。采用植物区系谱、相关性分析、主坐标分析及聚类分析等方法,研究了中国不同地区滨海湿地植物区系性质及属分布区类型组成的类似关系。结果表明：中国不同地区滨海湿地植物属级分布类型所占的比例随着纬度降低,温带分布型呈递减趋势,热带分布型呈递增的特点,这与不同区系成分的生态特性和纬度梯度上的能量格局分布是一致的;不同滨海湿地植物区系Shannon-Weiner指数具显著差异（1.430-2.154）,而Simpson指数无明显变化（0.662-0.842）,区系间相关系数为0.369-0.989;通过聚类分析和主坐标分析获得的聚类树状图和最小生成树,可将9个滨海湿地划分为5个集合组,较为一致地揭示了植物区系的类似性和分布格局。多种分析方法对比结合能客观地反映植物区系中属分布区类型关系的类似性,可为多个滨海湿地区系地理分布类似性的比较提供有效依据和参考。     

High altitude montane wetland vegetation classification of the Eastern Free State,South Africa

Wetlands occur where biotic and abiotic conditions combine to create unique habitats and plant assemblages. These systems have anaerobic or hydric soil resulting from waterlogging and are found across all nine biomes in South Africa. Wetlands can thus be regarded as hosting azonal vegetation. On Platberg, the freshwater wetlands are embedded within the Grassland Biome forming distinct units. Platberg wetlands were surveyed and described to explain and document vegetation of this inselberg. Additional aims were to elucidate Afro-montane floristic links with the Drakensberg Alpine Centre, and provide data for conservation management. The study site is located in the Eastern Free State, South Africa, on edge of the Great Escarpment. It is one of an archipelago of more than 20 inselbergs stretching north from the Drakensberg. A total of 51 sample plots (30 m²) were located in a randomly stratified manner within the wetland units to include all variations in the vegetation. The data was analysed using the TWINSPAN classification algorithm, refined by Braun-Blanquet procedures. The analysis showed the wetlands divided into five communities, six sub-communities and six variants. The wetland communities had an average of 13.56 species per relevé, ranging from 7 to 29 species per sample plot. Numerous floristic links with the Drakensberg Alpine Centre, the Cape Floristic Region and the Grassland biome were found. Platberg shows vegetation and hydrogeological affinity with low altitude freshwater and the high altitude Lesotho Mires of the Drakensberg Alpine Centre. A list of high altitude wetland species was compiled.     

Prioritising wetlands subject to secondary salinisation for ongoing management using aquatic invertebrate assemblages: a case study from the Wheatbelt Region of Western Australia

Secondary salinisation is recognised worldwide as a threat to aquatic biodiversity. Wetlands in the Wheatbelt Region of Western Australia are particularly affected as a result of clearing of deep-rooted native vegetation for agriculture. Between 1996 and 2001, the Western Australian government nominated six natural diversity recovery catchments (NDRCs), being catchments with high value and diverse wetlands in need of protection. One, the Buntine–Marchagee NDRC, supports approximately 1000 wetlands in varying states of salinisation. The challenge is to prioritise these wetlands for ongoing management. In this paper we propose an approach to prioritise representative wetlands using aquatic invertebrates. On the basis of hydrology, salinity and remnant vegetation, 20 wetlands covering a range of salinities were selected for sampling of water quality and aquatic invertebrates. Of the 202 taxa recorded, most endemic taxa occurred in fresh/brackish wetlands, while hypersaline wetlands supported predominantly cosmopolitan species. Taxa richness was greater in fresh/brackish than saline and hypersaline wetlands, with conductivity explaining 83 % of between-wetland variation in taxa richness. Classification using invertebrate assemblages separated fresh/brackish, saline and hypersaline wetlands, with greatest between-year variability within saline and hypersaline sites. Wetlands were ranked using taxa diversity, presence of conservation-significant taxa and temporal similarity. Mean rank across indices provided the final overall order of priority. Hypersaline wetlands were ordered separately to the fresher water wetlands (fresh/brackish and saline) so that priority for future management was detailed for both types of wetlands. The analysis indicated that although fresh/brackish sites support the highest biodiversity, naturally saline sites also supported wetland assemblages worthy of ongoing protection.     

Floristic characteristics of the wetland sites on dry southern slopes of the Alborz Mts., N. Iran: The role of altitude in floristic composition

The Alborz Mountains, the second largest range in Iran, is, on its southern slopes, mainly covered by steppe vegetation. These dry slopes also include ‘green islands’ of wetland. Floristic diversity and environmental characteristics of 45 of these little-studied wetland sites have been assessed along an altitudinal gradient using one-way ANOVA, Pearson r and detrended correspondence analysis/canonical correspondence analysis (DCA/CCA) analyses. The wetlands proved to be of conservation importance with 310 plant taxa, including 35 endemics or subendemics. Predictably, and consistent with the phytosociological classification of Klein [2001. La végétation altitudinale de L’Alborz Central (Iran): Entre les régions Irano-Touranienne et Euro-sibérienne. Institut Français de Recherche en Iran, Téhéran], there were parallel changes in vegetation both within wetlands and the surrounding steppes and in DCA/CCA analyses altitude appeared to be the primary determinant of floristic composition. Upper mountain wetlands are particularly species-rich and contain many endemics and other species of a narrow phytogeographical distribution. Soil pH declined with altitude, perhaps in part as a consequence of low salinity (and high pH) in the mountains. Consistent with the work of Raunkiaer [1934. The life forms of plants and statistical plant geography. Clarendon Press, Oxford], hemicryptophytes are mainly restricted to upper mountain areas. Though correlated both directly with altitude and with correlation in DCA/CCA plots, phytogeography, life-form and soil pH fail to adequately explain the ecological processes that maintain the altitudinal gradient in vegetation types and species composition. Further studies on site productivity, soil chemistry and climate-related variables are, therefore, on-going in an attempt to understand more fully the ecosystem processes maintaining the diversity of these important wetland sites.     

Development issues in extending plant-based IBIs to forested wetlands in the Midwestern United States

Most plant-based indices of biotic integrity (IBIs) developed for wetlands have focused on emergent wetlands. A Vegetation Index of Biotic Integrity (VIBI-Forest) was developed for forested wetlands in the four large ecoregions of the Ohio. Assessing the effect of human disturbance on the ecological condition of wetland forests is complicated by several factors. First, forest canopies can remain largely intact even after significant degradation of the herb and shrub stratum. Second, increases in total diversity may not be good. In forested wetlands, a major artifact of disturbance is the addition of non-wetland or wetland native or adventive plant species adapted to full sun conditions to their floras. Initial versions of the VIBI-Forest metrics were very sensitive to disturbance-induced increases in diversity. Correcting this problem required modifying or replacing metrics so that only forest dependent species were included in metric calculations. The final VIBI-Forest included metrics which evaluated each forest stratum including the ground layer (% bryophyte), herb layer (shade or seed-less vascular plant species), shrub layer (subcanopy importance value (IV), relative density of young trees), canopy (canopy IV), and composite metrics for all vertical strata (Floristic Quality Assessment Index score, % hydrophytes, % sensitive, % tolerant). Assessing wetland forest condition is further complicated by the fact that some successional communities after canopy death or destruction (shrub swamp, marsh, wet meadow) may have intrinsic value as wetland community types. The solution is not to attempt to derive a one-size-fits-all assessment method but to derive separate protocols for other successional phases that are of value or interest.     

Temporal stability of vegetation indicators of wetland condition

Vegetation indices are widely employed to evaluate wetland ecological condition, and are expected to provide sensitive and specific detection of environmental change. Most studies evaluate the performance of condition assessment metrics in the context of the data used to calibrate them. Here we examined the temporal stability of the Florida Wetland Condition Index (FWCI) for vegetation of depressional forested wetlands by resampling sites in 2008 that were previously sampled to develop the FWCI in 2001. Our objective was to determine if FWCI, a composite of six vegetation-based metrics, provides a robust measure of condition given inter-annual variation in environmental conditions (i.e., rainfall) between sampling periods. To that end, we sampled 22 geographically isolated wetlands in north Florida that spanned a wide land use/land cover intensity gradient. Our results suggested the FWCI is robust. We observed no significant paired difference in FWCI across or within land use categories, and the relationship between FWCI in 2001 and 2008 was strong (r² = 0.88, p < 0.001). This was despite surprisingly high composition change. Mean Jaccard community similarity within sites between years was 0.30, suggesting that most of the herbaceous taxa were replaced, possibly because of different antecedent rainfall conditions or sampling during different phenological periods; both are contingencies to which condition indices must be robust. We did observe some evidence of convergence toward the mean in 2008, with the fitted slope relating 2001 and 2008 FWCI scores significantly below one (0.63, 95% CI = 0.53–0.73). The most variable FWCI component metric was the proportional representation of obligate wetland taxa, suggesting that systematic changes may have been induced by different hydrologic conditions prior to sampling; notably, however, FWCI computed without this component still exhibited a slope significantly less than 1 (0.72, 95% CI = 0.61–0.88). Moreover, there was evidence that species lost from reference sites (higher condition) were replaced by taxa of lower floristic quality, while species lost from agricultural sites (consistently the lowest condition land use category) were replaced by species of higher quality. A significant positive association between FWCI and the ratio of coefficients of conservatism (CC) of species lost to those gained suggests some overfitting in FWCI development. However, despite modest evidence of overfitting, FWCI provides temporally consistent estimates of wetland condition, even under conditions of substantial taxonomic turnover.     

Ants and plants as indicators of biodiversity,ecosystem services,and conservation value in constructed grasslands

Grasslands are constructed for soil and wildlife conservation in agricultural landscapes across Europe and North America. Constructed grasslands may mitigate habitat loss for grassland-dependent animals and enhance ecosystem services that are important to agriculture. The responses of animal species richness and abundance to grassland habitat quality are often highly variable, however, and monitoring of multiple taxa is often not feasible. We evaluated whether multiple animal taxa responded to variation in constructed grassland habitats of southwest Ohio, USA, in ways that could be predicted from indicators based on quality assessment indices, Simpson diversity, and the species richness of ants and plants. The quality assessment indices included a widely used Floristic Quality Assessment (FQA) index, and a new Ant Quality Assessment (AntQA) index, both based on habitat specificity and species traits. The ant and plant indicators were used as predictor variables in separate general linear models of four target taxa—bees, beetles, butterflies and birds—with response variables of overall species richness and abundance, and subsets of taxa that included the abundance of ecosystem-service providers and grassland-associated species. Plant Simpson diversity was the best-fitting predictor variable in models of overall bee and beetle abundance, and the abundance of bees classified as ecosystem-service (ES) providers. FQA and plant richness were the best predictors of overall butterfly species richness and abundance. Ant species richness was the best predictor of overall bird species richness and abundance as well as the abundance of ES birds, while the AntQA index was the best predictor for the abundance of grassland bird and butterfly species. Thus, plant Simpson diversity and ant species richness were the most effective indicators for complementary components of grassland animal communities, whereas quality assessment indices were less robust as indicators and require more knowledge on the habitat specificity of individual ant and plant species.     

Restoring prairie pothole wetlands: does the species pool concept offer decision‐making guidance for re‐vegetation?

Question: Do regional species pools, landscape isolation or on‐site constraints cause plants from different guilds to vary in their ability to colonize restored wetlands? Location: Iowa, Minnesota, and South Dakota, USA. Methods: Floristic surveys of 41 restored wetlands were made three and 12 years after reflooding to determine changes in local species pools for eight plant guilds. The effect of landscape isolation on colonization efficiency was evaluated for each guild by plotting local species pools against distance to nearby natural wetlands, and the relative importance of dispersal vs. on‐site constraints in limiting colonization was explored by comparing the local species pools of restored and natural wetlands within the region. Results: Of the 517 wetland plant taxa occurring in the region, 50% have established within 12 years. The proportion of the regional species pool represented in local species pools differed among guilds, with sedge‐meadow perennials, emergent perennials and floating/submersed aquatics least represented (33‐36%) and annual guilds most represented (74‐94%). Colonization‐to‐extinction ratios suggest that floating/submersed aquatics have already reached a species equilibrium while sedge‐meadow and emergent perennials are still accumulating species. Increasing distance to nearest wetlands decreased the proportion of the regional species pool present in local pools for all guilds except native annuals and woody plants. The maximum proportion predicted, assuming no distance constraint, was comparable to the lowest‐diversity natural wetlands for most perennial guilds, and also lower than what was achieved in a planted, weeded restoration. Conclusions: A biotic constraints seem to limit the colonization of floating/submersed aquatics into natural or restored wetlands, whereas all other guilds are potentially constrained by dispersal or biotic factors (i.e. competition from invasive species). Using species pools to evaluate restoration progress revealed that immigration potential varies considerably among guilds, that local species richness does not necessarily correspond to immigration limitations, and that some guilds (e.g. sedge‐meadow perennials) will likely benefit more than others from being planted at restoration sites.     

Comparison of created and natural freshwater emergent wetlands in Connecticut (USA)

Five three- to four-year old created palustrine/emergent wetland sites were compared with five nearby natural wetlands of comparable size and type. Hydrologic, soil and vegetation data were compiled over a nearly two-year period (1988-90). Created sites, which were located along major highways, exhibited more open water, greater water depth, and greater fluctuation in water depth than natural wetlands. Typical wetland soils exhibiting mottling and organic accumulation were wanting in created sites as compared with natural sites. Typha latifolia (common cattail) was the characteristic emergent vegetation at created sites, whereas a more diverse mosaic of emergent wetland species was often associated with Typha at the natural sites. Species richness was slightly higher in created (22–45) vs. natural (20–39) wetlands, but the mean difference (33 vs. 30) was not significant. Nearly half (44%) of the 54 wetland taxa found at the various study sites were more frequently recorded at created than natural wetlands. The presence of mycorrhizae in roots of Typha angustifolia (narrow-leaved cattail) and Phragmites australis (common reed) was greater at created than natural wetlands, which may be related to differential nutrient availability. Wildlife use at all sites ranged from occasional to rare, with more sightings of different species in the natural (39) than created (29) wetlands. The presence of P. australis and introduced Lythrum salicaria (purple loosestrife) may pose a threat to future species richness at the created sites. One created site has permanent flow-through hydrology, and its vegetation and wildlife somewhat mimic a natural wetland; however, the presence of P. australis and its potential spread pose an uncertain future for this site. This study suggests the possibility of creating small palustrine/emergent wetlands having certain functions associated with natural wetlands, such as flood water storage, sediment accretion and wildlife habitat. It is premature to evaluate fully the outcome of these wetland creation efforts. A decade or more is needed, emphasizing the importance of long term monitoring and the need to establish demonstration areas.     

FQA:一种基于物种保守性的植物区系质量评价方法

植物区系质量评价法(FQA)是一种利用植物物种对特定生境的保守性和植物群落的物种丰富度快速评估栖息地质量的方法.基于样方物种组成和专家赋值的植物物种保守系数,运用简单的公式即可计算出样方的植物区系质量指数(FQI).该指数能够反映植被的完整性和退化程度,可以用于对栖息地质量进行时空对比,已经在美国、加拿大等十余个国家广泛应用.本文介绍该方法的原理、计算公式和应用案例,为生态管理工作者和研究人员提供一种简单、可重复、可对比的生境质量评估工具.     

Macroinvertebrate community convergence between natural,rehabilitated, and created wetlands

Wetland restoration practices can include rehabilitating degraded wetlands or creating new wetlands. Empirical evidence is needed to determine if both rehabilitated and created wetlands can support the same macroinvertebrate communities as their natural counterparts. We measured long‐term macroinvertebrate community change in seasonal wetlands known as Delmarva Bays in Maryland, U.S.A. We compared a rehabilitated, a created, and a natural Delmarva Bay. We hypothesized that the created and rehabilitated wetlands would develop different macroinvertebrate communities. We also hypothesized that the community composition of the rehabilitated wetland would become more similar to that of the natural wetland than to that of the created wetland over 9 years encompassed by this study. We monitored the macroinvertebrates, including both predators and primary consumers, and environmental conditions in the three wetlands from March to August in 2005, 2006, 2007, and 2012. Cluster analysis indicated that from 2005 to 2007, the macroinvertebrate community of the rehabilitated wetland and the created wetland were more similar to each other than to the natural wetland. In 2012, the rehabilitated wetland was more similar to the natural wetland than to the created wetland. This similarity was driven principally by changes in the composition of primary consumer taxa. Our results suggest that rehabilitated Delmarva Bays are more likely to support a natural macroinvertebrate community than are created wetlands. Restoration practices that rehabilitate existing wetlands may be preferred over practices that create new wetlands when restoration project goals include developing natural macroinvertebrate communities in a short period of time.     

A comparison of created and natural wetlands in Pennsylvania,USA

Recent research suggests that created wetlands do not look, or function, like the natural systems they are intended to replace. Proper planning, construction, and the introduction of appropriate biotic material should initiate natural processes which continue indefinitely in a successful wetland creation project, with minimal human input. To determine if differences existed between created and natural wetlands, we compared soil matrix chroma, organic matter content, rock fragment content, bulk density, particle size distribution, vegetation species richness, total plant cover, and average wetland indicator status in created (n = 12) and natural (n = 14)wetlands in Pennsylvania (USA). Created wetlands ranged in age from two to 18 years. Soils in created wetlands had less organic matter content, greater bulk densities, higher matrix chroma, and more rock fragments than reference wetlands. Soils in reference wetlands had clay loam textures with high silt content, while sandy clay loam textures predominated in the created sites. Vegetation species richness and total cover were both greater in natural reference wetlands. Vegetation in created wetlands included a greater proportion of upland species than found in the reference wetlands. There were significant differences in soils and vegetation characteristics between younger and older created wetlands, though we could not say older created sites were trending towards the reference wetland condition. Updated site selection practices, more careful consideration of monitoring period lengths, and, especially, a stronger effort to recreate wetland types native to the region should result in increased similarity between created and natural wetlands.     

The application of a framework for assessing ecological condition and sustainability of use to three wetlands in Malawi

In Africa, the direct use of wetlands has long contributed to livelihoods, but use may lead to the degradation of wetlands. In order to better understand how the biophysical features of a wetland influence the sustainability of its use, an investigation was undertaken of the ecological condition and use of three wetlands in the Kasungu District, Malawi, where human pressures on wetlands are high. The first wetland, at the head of the catchment, had sandy soils and a gentle longitudinal slope, the second wetland, lower in the catchment, had clay soils and a steeper longitudinal slope, and the third wetland was intermediate. A framework was applied to score five functional components of ecological condition: hydrology, geomorphology, soil organic matter (SOM) accumulation, nutrient cycling and vegetation composition in terms of human impact, based on pre-defined field indicators. The framework highlighted particular vulnerabilities of individual wetlands in the face of human pressure. Vulnerability varied greatly across the wetlands in terms of: recovery of native vegetation composition following cultivation, geomorphic change through gully erosion and depletion of SOM. The framework is recommended for wider application in Africa as a means of highlighting the specific vulnerabilities of individual wetlands and for the improved focus of organizations which promote the ecologically sustainable use of wetlands.