•The impacts of sediment size, channel velocity and plant density on sediment deposition inside P. australis canopies were studied.•A method was proposed to predict the length of the diminished ...deposition region inside an emergent canopy of vegetation.•The sediment supply inside a canopy was not limited when the ratio of the advection time to the particle settling time was κ < 0.4 but was limited at κ > 1.
In this study, laboratory experiments were performed to investigate the impacts of sediment size, channel velocity and plant density on sediment deposition inside an emergent canopy constructed with Phragmites australis (P. australis) that included real plant morphology. Three sediment sizes (ds = 10, 22 and 48 μm), three plant densities (n = 0.006, 0.018 and 0.027 cm−2) and various mean channel velocities (U0 = 6 to 17 cm/s) were considered. Different mean channel velocities corresponded to the presence or absence of sediment resuspension in the bare channel, which led to distinct deposition patterns. Inside canopies, sediment deposition was dominated by the near-bed turbulent kinematic energy (near-bed TKE). At very low mean channel velocities (i.e., no resuspension in the bare channel), the pure deposition inside the canopy was the same as that in the bare channel. As the mean channel velocity increased but resuspension did not occur in the bare channel, the local vegetation-induced turbulence led to an increase in near-bed TKE within the canopy leading edge region, further causing the formation of a diminished deposition region. When the mean channel velocity was sufficiently large to produce resuspension in the bare channel, diminished and enhanced deposition regions were observed inside the canopy compared to the bare channel. A prediction method considering the impacts of sediment size, channel velocity, plant density and plant morphology was proposed to predict the length of the in-canopy diminished deposition region. The predictions and measurements were consistent. Different sediment sizes, channel velocities and plant densities led to two distinct sediment supply conditions inside the canopies. When sediment supply was not limited, finer sediment and/or sparser canopies led to longer diminished deposition regions, but the pure deposition inside the canopies remained constant. When sediment supply was limited, a different deposition pattern was observed. The pure deposition decreased along the canopy length, but the resuspension in the bare channel and canopy leading edge region might compensate for the limited sediment supply inside the canopy. A threshold representing the ratio of the advection time throughout the canopy to the particle settling time, κ, was defined to evaluate whether the sediment supply inside the canopy was limited. The sediment supply was not limited at κ < 0.4 but was limited at κ > 1.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Soil salinization has become a widespread threat to the structure and ecological functioning of inland wetlands globally. Soil seed banks can be important for plant regeneration in salinizing ...wetlands. To explore the effects of soil salinization on soil seed banks and their potential role in revegetation, we studied the structure and composition of plant communities and soil seed banks along a soil salinization gradient, and analyzed the responses of Carex-dominated and Phragmites-dominated communities to saline-alkaline stress in the Songnen Plain, China. We found that the dominant species of aboveground vegetation were different along the soil salinization gradient. Carex spp. dominated in the non-salinized and mild salinity wetlands, and Phragmites australis dominated in wetlands with moderate and high levels of salinity. The species richness of aboveground vegetation, and the density and richness of soil seed banks were higher in wetlands with lower salinity. The structural equation model indicated that the difference in soil salinization was directly associated with the aboveground species richness, and density and richness of the soil seed banks, while it was indirectly associated with the density and richness of the soil seed banks by directly affecting the composition and the species richness of the aboveground vegetation. Soil seed banks in Phragmites communities were more tolerant of saline-alkaline stress than Carex communities. This study indicates that soil salinization affects the size and composition of soil seed banks and limits their role in plant regeneration in wetlands of the Songnen Plain. In addition to hydrological regulation, the reduction of soil salinity is necessary to protect and restore biodiversity in salinizing wetlands.
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•Density and richness of soil seed bank decreased along soil salinization gradient.•Soil salinization directly and indirectly affects the soil seed bank in wetlands.•Phragmites community was more tolerant of saline-alkaline stress than Carex.•Improvement of soil salinization is necessary to protect wetland biodiversity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Magnetic biochar has been widely used in the removal of aquatic pollutants due to its strong adsorption capacity and recyclability. However, the nutrient deficiency caused by magnetic biochar reduces ...plant performance and limits its use. The effects of magnetic biochar (derived from either eucalyptus wood or pig manure compost) on soil Cd, Zn, and Pb bioavailability to Phragmites australis L. (reed) and soil microbial community were investigated in a pot experiment. We also examined treatments of magnetic biochar with P supplementation and unmodified biochar with Fe addition to elucidate the mechanism by which magnetic biochar affects plant growth. We found that the addition of magnetic biochar significantly reduced the concentrations of available heavy metals in soil and inhibited heavy metal uptake by reeds. It also promoted the formation of iron plaque on reed roots to inhibit metal translocation. However, compared to unmodified biochar, magnetic biochar reduced reed performance, as indicated by the reduced plant biomass and photosynthetic ability, and it also reduced the biomass of soil bacteria and fungi. This was due to the interception of P by the iron plaque and the reduced concentration of soil available P. Collectively, although magnetic biochar exhibited a strong potential for heavy metal remediation, P supplementation is recommended to maintain plant performance and soil health when applying magnetic biochar.
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•Recyclable magnetic biochar was useful for soil heavy metal remediation.•The use of magnetic biochar promoted the formation of iron plaque on the reed root.•The iron oxide from magnetic biochar reduced soil P availability.•Plant performance and soil microbial biomass were reduced due to P deficiency.•P supplementation should be recommended in magnetic biochar-applied soil.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Targeted grazing to control undesirable plant species is increasingly of interest across a diversity of ecosystems, particularly as an alternative or complement to widely used herbicides. However, ...there are limited comprehensive evaluations of targeted grazing that evaluate both invasive species management effectiveness and potential negative effects on the ecosystem. Phragmites australis, a tall-statured, dense perennial invasive grass from Eurasia, is a pervasive problem in wetlands across the North American continent. As with many invasive species where management has historically relied on herbicides and resistance is a growing concern, land managers seek viable alternatives that have minimal negative ecosystem impacts. Grazing has been used for millennia to manage native Phragmites in Europe. Similarly, in its invasive range within North America, small-scale studies suggest Phragmites may be suppressed by grazers. Yet, the effectiveness of grazing at large scales and its effects on broader ecosystem properties remain largely unknown. We evaluated the influence of targeted grazing on vegetation, soil nutrients, and water nutrients over two years in large plots (∼300x the size of previous studies). We also tested the effects of mowing, a treatment that can be used to facilitate grazer access to large, dense Phragmites stands. In line with our predictions, we found that cattle grazing effectively suppressed invasive Phragmites over two years. Mowing reduced litter, and moderately reduced standing dead Phragmites, both of which suppress native plant germination in this system. However, these reductions in Phragmites were not accompanied by indications of native plant community recovery, as we had optimistically predicted. Despite the potential for grazing to reduce nutrient sequestration by plants and fertilize soils, we were surprised to find no clear negative effects of grazing on nutrient mobilization to groundwater or floodwater. Taken together, our findings indicate that targeted grazing, when implemented at broad scales over short time frames, is effective at achieving invasive plant management goals without sizable nutrient impacts. However, additional steps will be needed to achieve the restoration of diverse, robust native plant communities.
•Targeted grazing, particularly when combined with mowing, reduces Phragmites.•Grazing does not have sizable negative impacts on soil and water nutrients.•Native plant community recovery may require active revegetation post grazing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The presence of macrophytes is one of the most conspicuous features of wetlands and their presence distinguishes constructed wetlands from unplanted soil filters or lagoons. The macrophytes growing ...in constructed wetlands have several properties in relation to the treatment process that make them an essential component of the design. However, only several roles of macrophytes apply to constructed wetlands with horizontal subsurface flow (HF CWs). The plants used in HF CWs designed for wastewater treatment should therefore: (1) be tolerant of high organic and nutrient loadings, (2) have rich belowground organs (i.e. roots and rhizomes) in order to provide substrate for attached bacteria and oxygenation (even very limited) of areas adjacent to roots and rhizomes and (3) have high aboveground biomass for winter insulation in cold and temperate regions and for nutrient removal via harvesting. The comparison of treatment efficiency of vegetated HF CWs and unplanted filters is not unanimous but most studies have shown that systems with plants achieve higher treatment efficiency. The vegetation has mostly a positive effect, i.e. supports higher treatment efficiency, for organics and nutrients like nitrogen and phosphorus. By far the most frequently used plant around the globe is
Phragmites australis
(Common reed). Species of the genera
Typha
(
latifolia
,
angustifolia
,
domingensis
,
orientalis
and
glauca
) and
Scirpus
(e.g.
lacustris
,
validus
,
californicus
and
acutus
) spp. are other commonly used species. In many countries, and especially in the tropics and subtropics, local plants including ornamental species are used for HF CWs.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Restored and constructed semi-natural wetlands are increasingly used in the agricultural landscape to intercept nutrients from surface waters. Vegetated surface-flow wetlands remove more nitrogen (N) ...than those without vegetation. However, changes in N removal over time as differently vegetated wetlands progress from early successional stages to mature systems are less investigated. We monitored three different types of initial planting over the course of 12 years, with the aim to examine how planting of newly constructed wetlands affects long-term N removal. All our data were collected in an experimental wetland facility in south-western Sweden. The facility consists of 18 identical small (ca. 25 m2) surface-flow wetlands, simulating semi-natural wetlands in an agricultural landscape. Initially, the 18 wetlands were randomly divided into three treatments (vegetation types) with six replicates each and planted with (1) emergent vegetation, (2) submerged vegetation and (3) no vegetation for free development. Vegetation succession afterwards progressed uninhibited in all wetlands. Emergent vegetation wetlands initially removed more N than both submerged vegetation and free development wetlands. We found that N removal in submerged vegetation and free development wetlands increased with ecosystem age, whereas N removal in emergent vegetation wetlands did not. N removal in all three vegetation types converged when the wetlands reached a more mature state, around 8 years after wetland construction. However, although all wetlands contained emergent vegetation in year 8, the proportion of emergent vegetation cover and vegetation composition still differed substantially between wetland types. Our study indicates that it is not the cover of emergent vegetation per se which promotes higher N removal in more mature wetlands, but the maturation process itself; mature wetlands despite differing emergent vegetation coverage achieved equally high N removal. In conclusion, once wetlands reach maturity, beneficial effects of initial planting on N removal disappear.
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•Nitrogen removal in 18 experimental wetlands from construction to maturity (12 years)•Comparing three vegetation types: emergent, submerged and free development•Initially highest nitrogen removal in emergent vegetation wetlands•Equally high nitrogen removal in all types when wetlands had reached maturity
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Environmental pollution with plastic waste and deforestation has led to increase research into the development of new natural fibers. Typha domingensis and Phragmites australis was used to make ...sustainable paper sheet and rigid containers packaging. Characterization of structural, mechanical, barriers, safety and end-of-life properties of Typha paper coated with polyolefins or polylactic acid was performed. Cellulose extraction was done at, 10 % NaOH at 120 °C for 90 min, the cellulose and fibers of these plants were used to produce a paper sheet and trays. The results showed that sheets made from Typha were 100 % recyclable and, showed mechanical properties comparable (5900 MPa) to a commercial Mitsubishi paper (7000 MPa) at parity of grammage. Typha and Reeds trays were permeable to water vapors and oxygen, but resistant to fat. The results LCA analysis showed that Typha trays had an environmental impact three times lower than aluminum trays, the most use in Senegal.
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•Typha cellulose pulp was tested for papermaking purposes.•Typha papers exhibit mechanical properties comparable to Mitsubishi paper.•Typha/Reeds trays coated with PLA were permeable to water and oxygen vapors.•Typha and Reeds trays coated with Paramelt 2248 and PLA were resistant to fat.•Typha paper could be fit application in secondary food packaging.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A functional response–effect approach could predict how environmental changes affect ecosystem functioning. However, few studies have applied this approach to inner saline–alkaline marsh ecosystems ...where soil saline–alkaline, flooding/drought and nutrients stresses threat ecological functioning. To disentangle the relationships between environmental conditions and ecosystem functioning, a total of 81 plots were investigated across 22 marsh sites dominated by Phragmites australis and Bolboschoenus planiculmis in Western Songnen Plain wetlands, China. For both plant communities combined, deep flooding supported communities with higher specific leaf area (SLA), plant height and leaf nitrogen (N) content but lower leaf thickness. On the contrary, high soil salt content induced low leaf N and phosphorus (P) content, SLA and plant height. Only light acquisition–related trait, plant height and SLA, was the key traits which determined the relationships between ecosystem functioning (aboveground biomass) and saline–alkaline wetland environment. Yet indirect key traits related nutrient and water acquisition such as leaf thickness, N and P content were also found, and mediated the response of aboveground biomass through the allometric relationships with plant height or SLA. For the individual species community, only plant height was the key trait shared by P. australis and B. planiculmis, indicating the universality of plant height as a key trait for grass and sedge plants to explain how ecosystem functioning responds to abiotic factors. Hence, our findings suggest that saltmarsh plants are more inclined to alter light–acquisition traits to mediate the response of ecosystem functioning to environmental changes and that plant height is a particularly useful trait to predict plant productivity in earth system models under future environmental changes in inner saline–alkaline wetlands.
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•SLA, plant height and leaf N responded to flooding positively but LT negatively.•Leaf N, P, SLA and plant height strongly responded to soil salt content negatively.•Plant height and SLA affected aboveground biomass positively.•Plant height was universal as key trait for grass and sedge plants.•Saltmarsh plants alter light–acquisition traits to mediate adaptation of ecosystem functions to environmental changes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Strategies for remediation of per- and polyfluoroalkyl substances (PFAS) generally prioritise highly contaminated source areas. However, the mobility of PFAS in the environment often results in ...extensive low-level contamination of surface waters across broad areas. Constructed Floating Wetlands (CFWs) promote the growth of plants in buoyant structures where pollutants are assimilated into plant biomass. This study examined the hydroponic growth of Juncus krausii, Baumea articulata and Phragmites australis over a 28-day period for remediation of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) contaminated (0.2 µg/L to 30 µg/L) urban stormwater. With increasing PFOA and PFOS concentrations, accumulation in plant species increased although root and shoot distribution varied depending on PFAS functional group. Less PFOA than PFOS accumulated in plant roots (0.006–0.16 versus 0.008–0.68 µg/g), while more PFOA accumulated in the plant shoots (0.02–0.55 versus 0.01–0.16 µg/g) indicating translocation to upper plant portions. Phragmites australis accumulated the highest overall plant tissue concentrations of PFOA and PFOS. The NanoSIMS data demonstrated that PFAS associated with roots and shoots was absorbed and not just surface bound. These results illustrate that CFWs have the potential to be used to reduce PFAS contaminants in surface waters.
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•Hydroponic growth of plants to remediate PFAS from stormwater were examined.•PFOA Translocation factors were found to be significantly higher compared to PFOS.•NanoSIMS data clearly demonstrate the presence of PFOA and PFOS within plant tissue.•Highest overall PFOA and PFOS removal efficacies were for Phragmites australis.•CFWs have the potential to reduce PFOA and PFOS contaminants in surface waters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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