Scirpus Cyperinus Research Articles

A new alien species Scirpus cyperinus (Cyperaceae) to the flora of the Smolensk Region

An alien North American species, Scirpus cyperinus (L.) Kunth (Cyperaceae), earlier known in Russia only in the Kostroma Region, was found in the Smolensk Region. Characteristics of the locality of the species are given and plant communities with its participation are described. The monodominant phytocoenoses formed by this species are combined into the new ass. Junco effusi–Scirpetum cyperini ass. nov. The new locality of abundant occurrence of the species is removed from its primary range and known locations in Eastern Europe.

Litter decomposition and nutrient dynamics of four macrophytes in intact, restored, and constructed freshwater marshes of Canada

The restoration and construction of wetlands offer opportunities to rewet soils, inhibit decomposition, and enhance nutrient retention in decomposing litters. Here, we report the decomposition rates and nutrient dynamics of macrophyte litters in intact, restored, and constructed wetlands. A 2.1‐year litterbag experiment of four common freshwater macrophytes (Phalaris arundinacea, Phragmites australis, Scirpus cyperinus, and Typha latifolia) was conducted in eight freshwater marshes (three intact, four restored, and one constructed) within three sites in Manitoba and Ontario, Canada, which varied in restoration age, inundation periods, and surrounding land uses. Litter mass loss and N and P dynamics were measured. Litter decomposition rates (k) followed the order of P. arundinacea (0.42 ± 0.03 year−1) > T. latifolia (0.31 ± 0.03 year−1) > P. australis (0.19 ± 0.01 year−1) > S. cyperinus (0.13 ± 0.01 year−1) in most wetlands and were positively correlated to the initial litter N concentration. Litters decomposed fastest under seasonally inundated conditions rather than permanent inundation. N and P retention in litters were significantly affected by both initial litter N and P concentration and wetland surrounding land uses. After 2.1 years of decomposition, the N:P ratio of all litters converged to 20 to 28:1, regardless of the initial litter N:P ratio or N or P concentrations. The effectiveness of wetland restoration in slowing decomposition and enhancing nutrient accumulation depends on the quality of the input litters and wetland characteristics, including inundated periods and surrounding anthropogenic disturbances.

Effects of macrophyte species and biochar on the performance of treatment wetlands for the removal of glyphosate from agricultural runoff

Glyphosate is the most widely used herbicide in the world, and consequently has polluted numerous water bodies through agricultural runoff. Treatment wetlands (TWs) have shown great promise for mitigating such pesticide contamination. The objectives of our study were to determine the effects of adding biochar to subsurface flow TW substrate, and to evaluate the performance of three North American macrophyte species (Phragmites australis subsp. americanus, Scirpus cyperinus and Sporobolus michauxianus) for removal of glyphosate. A synthetic agricultural runoff comprising 50 μg/L of glyphosate was applied to water-saturated TW mesocosms with mature vegetation during a 5.5-week period. Average removal efficiency, calculated on a mass balance basis, reached 78 and 82% for mesocosms with biochar (without and with plants, respectively), and 54 to 76% for those with macrophytes. Sporobolus michauxianus showed a lower evapotranspiration rate and less anoxic conditions in the lower part of the substrate, which resulted in lower overall removal performance. Aminomethylphosphonic acid (AMPA), the main toxic metabolite of glyphosate, was detected in all mesocosms, but at higher levels in planted ones. Results show that both the sorption capacity of biochar and the biodegradation processes associated with macrophytes contribute to glyphosate removal in TWs. Additionally, our results suggest that species selection is important to enhance favorable conditions and maximize removal of targeted pollutants.

Drying and dehydration of native ornamental plants of Arunachal Pradesh and its value addition

Wild and underutilized plant species particularly ornamental flowers and foliage can be converted into value added products using drying and dehydration technique. The present studies have been carried out to explore the potential of wild ornamental plants of Arunachal Pradesh for the purpose of dry flower making. The plant parts have been collected from different places viz. Pasighat, Bodak, Renging, Menchuka, Bomdilla, Tenga Valley, Yingkiong, etc. A total of fourteen (14) potential plant species had been identified for drying and dehydration without any loss in quality and appearance. The species identified includes Pteridium aquilinum (Eagle Fern/Western Bracken Fern), Lycopodium clavatum (Stag’s Horn Clubmoss/Ground pine), Nicandra phylasoides (Apple of Peru), Scirpus cyperinus (Wool grass), Barleria cristata (Phillipine violet), Cortaderia selloana (Pampas grass), Anaphilis busua (Tall pearly everlasting), Miscanthus spp. (Silver grass), lichens, Phragmites spp. (common reed grass), Davallia bullata (Rabbit foot fern), Tillandsia spp. (Spanish moss), Elsholtzia cristata (Crested late summer mint) and Setaria parviflora (Bristly foxtail). Maximum number of genera belongs to the family of Poaceae followed by Cyperaceae. Seed heads of Cortaderia selloana, Miscanthus spp., Phragmites spp., Erioscirpus comosus, Scirpus cyperinus, Setaria parviflora; leaves of Pteridium aquilinum, Lycopodium clavatum, Davallia bullata; fruits of Nicandra phylasoides, Elsholtzia cristata; flower of Anaphilis busua; dried calyx of Barleria cristata and stem of Tillandsia spp. had also been used for drying and value addition. A cottage industry based on floral craft can become a new area for self-employment of rural youth’s and women through this creative occupation. The quest for searching new materials which can be utilized as dried flowers never ends and in fact is the demand of the hour.

Effects of plants and biochar on the performance of treatment wetlands for removal of the pesticide chlorantraniliprole from agricultural runoff

Chlorantraniliprole (CAP), an emergent insecticide commonly replacing banned neonicotinoids, is used worldwide despite the risk of contaminating water bodies. Treatment wetlands (TWs) have shown great potential for mitigating various pesticides in agricultural runoff, but little is known about CAP removal. The aim of this study was to determine the effect of adding biochar to subsurface flow treatment wetlands (SSF TWs) and the performance of three macrophyte species (Phragmites australis subsp. americanus, Scirpus cyperinus and Sporobolus michauxianus) in CAP removal. Removal efficiency was monitored over a one-month period in water-saturated SSF mesocosms fed with synthetic agricultural runoff containing CAP. To reflect temporal changes in agricultural runoff dynamics, two CAP concentrations were used in influent: a peak concentration (4 μg/L) for the first week and a trace concentration (0.4 μg/L) for the three subsequent weeks. Results showed that mesocosms with biochar were very effective in removing CAP mass (90 to 99%) and remained so throughout the experimental period. On the other hand, the level of CAP removal achieved in planted mesocosms without biochar was low (less than 13%). Evapotranspiration contributed significantly to volume reduction, but no general pattern in CAP mass removal efficiency was detected among the planted treatments without biochar. However, planted treatments acted as buffer zones, accumulating CAP and reducing its peak mass in effluent. Evapotranspiration rates of Scirpus and Phragmites were higher than that of Sporobolus, resulting in a greater buffering effect. This study suggests that addition of biochar to SSF TW substrate is a promising approach for CAP mitigation in agricultural runoff, but long-term efficiency remains to be assessed.

The resistance and short‐term resilience of a restored extracted peatland ecosystems post‐fire: an opportunistic study after a wildfire

Bogs are known to be relatively resistant and resilient to fire, due to the dominance of wet Sphagnum mosses. Indeed, Sphagnum mosses by holding water, ensure bog resistance, and by regenerating from any fragments left post‐fire, ensure bog resilience. The return of several ecological attributes has been reported in the literature post‐restoration. However, the resistance and resilience have not yet been evaluated in restored peatlands. A fire affecting an extracted peatland restored 10 years ago provided the opportunity to (1) evaluate the losses post‐fire, in terms of phytobiomass and plant cover and (2) assess early vegetation recovery after one growing season post‐fire. The fire response of the restored peatland, in terms of resistance and short‐term resilience, differed between the main plant communities. Sphagnum Lawn communities (Sphagnum species from the Acutifolia subgenus and Eriophorum vaginatum) showed greater resistance to fire losing proportionally less phytobiomass (17%) than Wet Hollow communities (44%) (Sphagnum species from the Cuspidata subgenus and Scirpus cyperinus). Greater resistance of the Sphagnum Lawn likely comes from the Acutifolia Sphagnum species growing in dense carpets with good water retention, along with the E. vaginatum tussocks being able to retain humidity below the tussocks, whereas the looser growth habit of Cuspidata Sphagnum species do not have good capillary rise capacity and Scirpus produced litter that can produce a good fuel. This study reinforces the idea that a peatland restoration approach using reintroduction material dominated by Acutifolia Sphagnum species and tussock cottongrass provides a better resistance and short‐term resilience of restored peatlands.

Suitability of wetland macrophyte in green cooling tower performance

Green cooling towers, or thermal green-walls, recirculate hot water flowing through a living plant and porous material. Through convective and evaporative heat and mass transfer they can actively cool a building or an industrial heat waste. Thus they can provide an alternative cooling technology. Thermal green-walls use wetland plant species in highly constructed wetlands selected for their heat tolerance. In addition, they offer such co-benefits as carbon capture and control of local microclimates. Optimal heat rejection (HR) requires the plant rhizosphere to be completely inundated at temperatures much higher than the ambient air temperature, potentially inducing thermal physiological stress. To study the viability of specific plants within a HR system, we exposed three macrophytes, Iris versicolor, Scirpus cyperinus and Carex lurida, to hydroponic recirculating water at three different temperatures (25 °C, 35 °C, and 40 °C). We assessed the plant responses over a period of eight weeks by measuring photochemical efficiency, leaf temperature, stomatal conductance, Gs and biomass output. Plant biomass was highest at 35 °C (particularly in I. versicolor), even higher than ambient water temperature at 25 °C. We observed a general homeothermic-like response in Gs over a 5-week time period, but the response was species-specific with respect to temperature. Results suggests a possible leaf-level physiological acclimation mechanism as well as high maintenance of tissue moisture that allows macrophytes to tolerate hydro-thermal stress, and support their suitability to perform in HR systems at input temperature, Twin = 35 °C.

Spontaneous revegetation of a peatland in Manitoba after peat extraction: diversity of plant assemblages and restoration perspectives

There are very few studies on the spontaneous revegetation of cutover fens or bogs from which peat has been extracted to the minerotrophic layers. Most peatlands with fen-type residual peat have problems regenerating a plant cover satisfactorily from a restoration point of view. We nevertheless found a site (Moss Spur, Manitoba, Canada) presenting a substantial and diversified spontaneous plant cover. We estimated that the site would provide insights about natural revegetation processes operating in peatlands. Vegetation assemblages and environmental conditions were surveyed 19 years after extraction activities ceased. Moss Spur has densely revegetated (163 plant species, vegetation cover of 94%) with minimal human assistance. However, the composition of plant assemblages varies considerably across the site, depending on certain abiotic variables, particularly water pH, water table level, and the thickness of the residual peat layer. Moss Spur was remarkably wet considering the past peat extraction activities and the absence of active rewetting procedures. The high water table level may in part explain the successful revegetation. However, plant assemblages were not of equal quality from a restoration perspective. Some assemblages were highly diversified, and especially those dominated by Scirpus cyperinus, a species that should be further considered in peatland restoration projects to direct the recovery of the peatland towards a natural fen species composition.

Host Plants (Cyperaceae) of Ischnodemus rufipes Van Duzee (Hemiptera: Blissidae): Cyperus erythrorhizos in Unpredictable Wetland Communities, Scirpus cyperinus in More Permanent Wetlands

Previous information on host plants of the blissid Ischnodemus rufipes Van Duzee has been limited to single observations in Florida on each of two sedges (Cyperaceae): Cyperus erythrorhizos and C. odoratus. In the piedmont of South Carolina, during extreme drought conditions in August 2008, I. rufipes was found on redroot flatsedge, C. erythrorhizos, which had colonized mudflats on exposed shorelines of Hartwell Lake in Clemson. Surveys to determine the host-plant range of I. rufipes were conducted from 2008 to 2012 in the Blue Ridge ecoregion of Georgia and North Carolina and coastal plain and piedmont of Georgia and South Carolina. The blissid exploits the short (floriferous) growth form of C. erythrorhizos, an annual sedge of unpredictable availability in ephemeral mudflats, while maintaining populations mainly on a perennial sedge, Scirpus cyperinus, in more persistent habitats. The blissid also develops on the generally taller C. erythrorhizos plants in more permanent wetlands. Only one generation of I. rufipes might be possible on annual sedges of inconstant occurrence, but the blissid is bivoltine on woolly sedge (woolgrass), S. cyperinus. Adults overwintered not only on host sedges (mainly S. cyperinus), but also on nonhost sedges and other graminoids, beginning as early as September. A mating pair was observed on S. cyperinus in mid-May, early instars in late May, and first-generation adults by mid-July. Early instars of a second generation (and a mating pair) were observed in mid-August. The late instars found sparingly on woolly sedge in late fall and early winter probably attain adulthood or die during winter; only adults were observed after January. New state records for I. rufipes are Arkansas, Oklahoma, and South Carolina.

A microbial link between elevated CO2 and methane emissions that is plant species-specific.

Rising atmospheric CO2 levels alter the physiology of many plant species, but little is known of changes to root dynamics that may impact soil microbial mediation of greenhouse gas emissions from wetlands. We grew co-occurring wetland plant species that included an invasive reed canary grass (Phalaris arundinacea L.) and a native woolgrass (Scirpus cyperinus L.) in a controlled greenhouse facility under ambient (380 ppm) and elevated atmospheric CO2 (700 ppm). We hypothesized that elevated atmospheric CO2 would increase the abundance of both archaeal methanogen and bacterial methanotroph populations through stimulation of plant root and shoot biomass. We found that methane levels emitted from S. cyperinus shoots increased 1.5-fold under elevated CO2, while no changes in methane levels were detected from P. arundincea. The increase in methane emissions was not explained by enhanced root or shoot growth of S. cyperinus. Principal components analysis of the total phospholipid fatty acid (PLFA) recovered from microbial cell membranes revealed that elevated CO2 levels shifted the composition of the microbial community under S. cyperinus, while no changes were detected under P. arundinacea. More detailed analysis of microbial abundance showed no impact of elevated CO2 on a fatty acid indicative of methanotrophic bacteria (18:2ω6c), and no changes were detected in the terminal restriction fragment length polymorphism (T-RFLP) relative abundance profiles of acetate-utilizing archaeal methanogens. Plant carbon depleted in 13C was traced into the PLFAs of soil microorganisms as a measure of the plant contribution to microbial PLFA. The relative contribution of plant-derived carbon to PLFA carbon was larger in S. cyperinus compared with P. arundinacea in four PLFAs (i14:0, i15:0, a15:0, and 18:1ω9t). The δ13C isotopic values indicate that the contribution of plant-derived carbon to microbial lipids could differ in rhizospheres of CO2-responsive plant species, such as S. cyperinus in this study. The results from this study show that the CO2–methane link found in S. cyperinus can occur without a corresponding change in methanogen and methanotroph relative abundances, but PLFA analysis indicated shifts in the community profile of bacteria and fungi that were unique to rhizospheres under elevated CO2.

Soil Properties Predict Plant Community Development of Mitigation Wetlands Created in the Virginia Piedmont, USA

The study investigated vegetative and soil properties in four created mitigation wetlands, ranging in age from three to ten years, all created in the Virginia Piedmont. Vegetation attributes included percent cover, richness (S), diversity (H'), floristic quality assessment index (FQAI), prevalence index (PI), and productivity [i.e., peak above-ground biomass (AGB) and below-ground biomass]. Soil attributes included soil organic matter (SOM), gravimetric soil moisture (GSM), pH, and bulk density (D(b)) for the top 10cm. Species dominance (e.g., Juncus effusus, Scirpus cyperinus, Arthraxon hispidus) led to a lack of differences in vegetative attributes between sites. However, site-based differences were found for GSM, pH, and SOM (P<0.001). Soil attributes were analyzed using Euclidean cluster analysis, resulting in four soil condition (SC) categories where plots were grouped based on common attribute levels (i.e., SC1>SC2>SC3>SC4, trended more to less developed). When vegetation attributes were compared between SC groups, greater SOM, lower D(b), more circumneutral pH, and higher GSM, all indicative of maturation, were associated with higher H' (P<0.05), FQAI (P<0.05), and total and volunteer percent cover (P<0.05), and lower AGB (P<0.001), PI (P<0.05), and seeded percent cover (P<0.05). The outcome of the study shows that site age does not necessarily equate with site development with soil and vegetation developmental rates varying both within and among sites. The inclusion of soil attributes in post-construction monitoring should be required to enhance our understanding and prediction of developmental trajectory of created mitigation wetlands.

Harvestable Nitrogen Accumulation for Five Storm Water Wetland Plant Species: Trigger for Storm Water Control Measure Maintenance?

As the use of constructed storm water wetlands to treat storm water runoff becomes more frequent, strategies for maintaining or increasing their pollutant removal over time must be examined. One potential strategy is plant harvesting at the water surface to remove nutrients that would otherwise be deposited back into the wetland during senescence. This technical note presents a first look at this strategy from a storm water management perspective. Vegetation was harvested from two storm water wetlands located in Smithfield and Pactolus, North Carolina, to evaluate the ability of five wetland plant species to sequester nitrogen. Biomass samples were collected from the following species of emergent vegetation: Pontederia cordata (Pickerelweed), Saururus cernuus (Lizard Tail), Scirpus cyperinus (Wool Grass), Sagittaria latifolia (Arrowhead), and Schoenoplectus tabernaemontani (Softstem Bulrush). Samples were collected immediately prior to senescence in September and October 2007 and analyzed for nitrogen content on a percent of biomass basis. At the Pactolus wetland the Pontederia cordata, Scirpus cyperinus, and Schoenoplectus tabernaemontani biomass retained significantly (p<0.05) more nitrogen than Sagittaria latifolia and Saururus cernuus. At the Smithfield wetland, Pontederia cordata and Sagittaria latifolia biomass retained significantly more nitrogen than Scirpus cyperinus and Saururus cernuus. Wetland maturity appears to have a direct relationship to harvestable nitrogen, which could explain why the relative amount of nitrogen sequestered in Scirpus cyperinus and Sagittaria latifolia varied between the two wetlands. A positive relationship existed between the density of harvested biomass and nitrogen removal for two species. To estimate the relative amount of harvestable nitrogen, a model for estimating total nitrogen loading in Coastal Plain watersheds in North Carolina was used to compare estimated inflow nitrogen mass to that which could theoretically be harvested. The harvestable N mass was greater than 20% of inflow nitrogen on an annual basis. Storm water wetland plant harvesting as a maintenance activity has potential to supplement wetland nitrogen removal.

Soil organic carbon pools and composition in a wetland complex invaded by reed canary grass

Reed canary grass (Phalaris arundinacea) invasion is prevalent in wetlands and riparian fringes, and due to differences in vegetative growth and residue quality relative to native species, P. arundinacea invasion could result in measurable effect on soil organic carbon (SOC) pools and composition. To examine these questions, plant biomass and soil samples were collected from areas invaded by P. arundinacea and areas colonized either by a native sedge Scirpus cyperinus or a mixed assemblage of 22 native species in a south-central Indiana (USA) wetland. Plant biomass composition (C, N, cellulose, lignin, and phenolics), total and water-extractable SOC pools were determined. S. cyperinus biomass contained (g kg−1 biomass) significantly (P < 0.05) more lignin (142.5 vs 72), phenolics (29.2 vs 11.2), and cellulose (260.5 vs 164.8) than P. arundinacea biomass. These constituents were also more abundant in mixed native plant material than in P. arundinacea biomass. Decomposition of plant biomass was related to residue composition with P. arundinacea shoot biomass decomposing 1.6 times faster than S. cyperinus material. SOC pools (Mg C ha−1, 0–30 cm) were larger under P. arundinacea (28.3) than under either S. cyperinus (23.9) or the mixed native species (21.8). Thus, the greater recalcitrance of native plant biomass did not translate into larger SOC pools. Furthermore, water-extractable organic C, N, and carbohydrates were significantly higher in the surface layer of soils supporting P. arundinacea than in native species. These results therefore indicate a clear effect of P. arundinacea invasion on the cycling and composition of soil organic matter at the study site.

Methane dynamics across wetland plant species

We examined patterns of methane flux, plant biomass, and microbial methanogenic populations in nine wetland plant species. Methane dynamics varied across plant functional groupings, with patterns distinctive among forbs, clonal dominants, and tussock/clump-forming graminoids. Carex stricta and Scirpus atrovirens showed the highest emissions (31.7 and 20.6 mg CH 4-C m −2 h −1), followed by other tussock- or clump-forming graminoids that averaged 11.0 mg CH 4-C m −2 h −1 ( Scirpus cyperinus, Glyceria striata, and Juncus effusus). The clonal dominants ( Phalaris arundinacea and Typha angustifolia) had the lowest methane emissions (1.3 and 3.4 mg CH 4-C m −2 h −1) of all seven graminoid species, and the forbs ( Mimulus ringens and Verbena hastata) emitted no detectable methane flux from their leaves. In general, methane emissions decreased with greater plant biomass. Terminal restriction fragment analysis (T-RFLP) of archaeal 16S rRNA revealed that the structure of the soil methanogen communities isolated from plant rhizospheres had no effect on methane flux. The relative proportions of the different terminal fragments were not correlated with either methane emissions or plant biomass. Methanogen populations from J. effusus soils were dominated by acetoclastic archaea of the Methanosarcinaceae and Methanosaetaceae families, while all other graminoid soils were colonized primarily by hydrogenotrophic archaea of the Methanobacteriaceae family. The results indicate that plant functional groups and plant biomass are useful in predicting methane flux differences across plant species, while soil methanogen community structure showed no distinguishable patterns.

Primary Productivity in 20-year Old Created Wetlands in Southwestern Virginia

Thousands of depressional wetlands accidentally formed as a result of pre-1977 contour coal mining in the Appalachian Mountains. Eleven 20-yr old sites were found in a watershed that did not receive acid mine drainage. The purpose of this study was to quantify and model above- and below-ground plant biomass in these created wetlands and to evaluate functional development. Sampling was stratified by weighted average of two plant communities, which corresponded to shallower and deeper water levels, facultative wetland and obligate wetland communities, respectively. In 1994, peak above-ground biomass averaged 473.7 g m−2 in the facultative wetland community and 409.5 g m−2 in the obligate wetland community. Scirpus cyperinus exhibited the highest peak above-ground biomass (51.8% of total biomass) and Typha latifolia ranked second. Canonical correspondence analysis detected positive effects of longer soil exposure to the atmosphere and greater sediment depth on above-ground biomass at the site (wetland ecosystem) level. Within communities, forward stepwise regression identified positive association of above-ground biomass with water soluble reactive P, water soluble NH3, decomposition rate over 507 d, live S. cyperinus tissue P content, and sediment depth. When these results are combined with prior studies conducted at the same 20-yr old sites, it appears that both structural and functional development has been arrested at a somewhat immature state resulting primarily from soil and hydrologic factors.

Examining the peat-accumulating potential of fen vegetation in the context of fen restoration of harvested peatlands

In order to focus efforts towards specific vegetation groups in fen restoration, knowledge of the peat-accumulating function of dominant fen species is critical. The decomposition rates of 3 species typical to undisturbed fens and 3 species that spontaneously colonize harvested fens were assessed. These species were incubated in both a restoration site (harvested fen) and an undisturbed fen to compare decomposition according to different environmental conditions. The average exponential decay coefficient (k) for all material types was slightly higher (circa 0.04·y−1 higher) in the harvested fen than those observed in the undisturbed fen. However, the litter type (leaves, roots/rhizomes, or bryophyte fragments) had the largest impact on the decomposition rates. The 2 tested bryophytes had lower k-values (between 0.14 and 0.11 for Polytrichum strictum and 0.06 for Sphagnum centrale) than the vascular plant litter (between 0.25 and 0.50). The annual primary production of the tested species was also measured to estimate the peat-accumulating capacity of each species. Scirpus cyperinus had an annual primary production that was 3 times higher (1500 g·m−2.y−1) than the other species (between 300 and 550 g·m−2.y−1). Estimates show that the harvested fen has a high peat-accumulating potential due to the high biomass production observed at this site.

Establishment and Evaluation of the Vegetative Community in A Surface Flow Constructed Wetland Treating Industrial Park Contaminants

A surface flow constructed wetland, designed to curve in a kidney shape in order to increase the length to width ratio to 5:1 was used to treat runoff from an industrial park. A natural wetland system located approximately 200 m downstream of the constructed wetland was selected to act as the vegetative community model for the constructed wetland. The selected model was a riparian, open water marsh dominated by emergent macrophytes. Baseline plant species surveying was conducted. In total, 21 emergent wetland plant species, 40 upland vascular plant species, 17 upland shrub species and 13 upland tree species were identified in the model site. The species from the model site were screened for suitability in the constructed wetland based on the following criteria: (a) phytoremediation potential (especially metal uptake), (b) sedimentation and erosion control, (c) habitat function, (d) public deterrent potential and (e) rate of plant establishment, tolerances and maintenance requirements. Transplantation was chosen as the main vegetation establishment methodology in the constructed wetland. The species woolgrass (Scirpus cyperinus) and soft rush (Juncus effusus) were chosen to dominate the interior berms and littoral edges of the constructed wetland cells. The buffer areas were dominated by meadowsweet (Spiraea alba var. latifolia) and the open water areas were dominated by cowlily (Nuphar variegate) and pickerelweed (Pontederia cordata) species. A diverse, self-sustaining vegetative community was successfully established in the constructed wetland. The transplant success was gauged by mortality census in the spring of 2003. Over all, 138 dead transplants were observed, many of which had died as a direct result of washout. These computes to an overall site establish success rate of about 87.3%. The species, which suffered the highest mortality rates, were the pickerelweed, with approximately 50 dead plants, the meadowsweet with 32 observed dead plants and woolgrass with 27 dead plants.

Seed bank response to wet heat and the vegetation structure of a Virginia pocosin1

Pocosins are shrub wetlands of the southeastern coastal plain maintained by fire. Increased herbaceous plant diversity has been reported after wildfire. To test the effect of radiant heating on the seed bank of pocosin-upland ecotones, wet heat treatments were applied to Sphagnum substrate from a Virginia small depression pocosin. The seedling emergence method was used to quantify wetland seedling abundance and richness. Extant vegetation was measured at each seed bank sampling area and the seed bank and vegetation were compared with Sorenson similarity values. No significant seedling abundance, richness, or evenness effects were detected among wet heat and control groups. However, the high wet heat treatment (75 °C) significantly reduced the density of Sphagnum cuspidatum capitula more than 80% relative to the control. Mean seed bank density was 6,209 seedlings/m2 (richness = 11) and was dominated by Scirpus cyperinus (97.8%), contained many early successional species. The seed bank did not closely resemble the extant vegetation. Pocosin canopy was sparse and dominated by Pinus serotina. The shrub-sapling stratum indicated co-dominance of Acer rubrum and ericaceous species, potentially indicating a shift from a shrub bog to a wet pine-hardwood community.

Assessment of The Biological Integrity of The Native Vegetative Community In A Surface Flow Constructed Wetland Treating Industrial Park Contaminants

A study was conducted to evaluate the biological integrity of a constructed wetland receiving landfill leachate and stormwater runoff from the Burnside Industrial Park, Dartmouth, Nova Scotia. The biological integrity of the constructed wetland was tested in the second growing season using vegetative community monitoring. The metrics analyzed were species diversity, species heterogeneity (dominance) and exotic/invasive species abundance. There was no significant difference in the plant species diversity between the constructed wetland and the reference site. However, the constructed wetland supported a higher plant species richness than the reference site. The top three species in the constructed wetland were tweedy’s rush (Juncus brevicaudatus), soft rush (Juncus effusus) and fowl mannagrass (Glyceria striata). In total, these three species occupied 46.4% of the sampled population. The top three species in the reference site were soft rush (Juncus effusus), sweetgale (Myrica gale) and woolgrass (Scirpus cyperinus). In total, these three species occupied a more reasonable 32.6% of the sampled population. The reference site supported greater biological integrity as it had greater heterogeneity and a smaller abundance of exotic and invasive species compared to the constructed wetland (3.8% versus 10.7%). Although poor heterogeneity and the presence of weedy, exotic species can be a sign of degraded biological health and future problems, these are also common indicators of a system simply undergoing early succession. As the constructed wetland matures, its plant biodiversity may actually decrease, but its integrity, as measured by exotic and invasive species abundance as well as heterogeneity, is expected to increase, so long as invasive species present in the constructed wetland remain controlled through weeding during the first few growing seasons.

Beaver herbivory on aquatic plants

Herbivores have strong impacts on marine and terrestrial plant communities, but their impact is less well studied in benthic freshwater systems. For example, North American beavers (Castor canadensis) eat both woody and non-woody plants and focus almost exclusively on the latter in summer months, yet their impacts on non-woody plants are generally attributed to ecosystem engineering rather than herbivory. Here, we excluded beavers from areas of two beaver wetlands for over 2 years and demonstrated that beaver herbivory reduced aquatic plant biomass by 60%, plant litter by 75%, and dramatically shifted plant species composition. The perennial forb lizard's tail (Saururus cernuus) comprised less than 5% of plant biomass in areas open to beaver grazing but greater than 50% of plant biomass in beaver exclusions. This shift was likely due to direct herbivory, as beavers preferentially consumed lizard's tail over other plants in a field feeding assay. Beaver herbivory also reduced the abundance of the invasive aquatic plant Myriophyllum aquaticum by nearly 90%, consistent with recent evidence that native generalist herbivores provide biotic resistance against exotic plant invasions. Beaver herbivory also had indirect effects on plant interactions in this community. The palatable plant lizard's tail was 3 times more frequent and 10 times more abundant inside woolgrass (Scirpus cyperinus) tussocks than in spatially paired locations lacking tussocks. When the protective foliage of the woolgrass was removed without exclusion cages, beavers consumed nearly half of the lizard's tail leaves within 2 weeks. In contrast, leaf abundance increased by 73-93% in the treatments retaining woolgrass or protected by a cage. Thus, woolgrass tussocks were as effective as cages at excluding beaver foraging and provided lizard's tail plants an associational refuge from beaver herbivory. These results suggest that beaver herbivory has strong direct and indirect impacts on populations and communities of herbaceous aquatic plants and extends the consequences of beaver activities beyond ecosystem engineering.