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Biological invasions pose a significant threat to ecosystems, disrupting local biodiversity and ecosystem functions. The genomic underpinnings of invasiveness, however, are still largely unknown, making it difficult to predict and manage invasive species effectively. The common reed (Phragmites australis) is a dominant grass species in wetland ecosystems and has become particularly invasive when transferred from Europe to North America. Here, we present a high-quality gap-free, telomere-to-telomere genome assembly of Phragmites australis consisting of 24 pseudochromosomes and a B chromosome. Fully phased subgenomes demonstrated considerable subgenome dominance and revealed the divergence of diploid progenitors approximately 30.9 million years ago. Comparative genomics using chromosome-level scaffolds for three other lineages and a previously published draft genome assembly of an invasive lineage revealed that gene family expansions in the form of tandem duplications may have contributed to the invasiveness of the lineage. This study sheds light on the genome evolution of Arundinoideae grasses and suggests that genetic drivers, such as gene family expansions and tandem duplications, may underly the processes of biological invasion in plants. These findings provide a crucial step toward understanding and managing the genetic basis of invasiveness in plant species. We provide a complete, telomere to telomere gap-free genome assembly for common reed that includes its B chromosome. Comparative genomic analysis revealed that tandem duplications may have contributed to the invasiveness potential of the species. [ABSTRACT FROM AUTHOR]

The use of constructed wetlands (CWs) is a promising approach for the remediation of hydrocarbon-polluted wastewater. The amendments of CWs with nutrients, surfactants, and aeration enhances the removal of pollutants from wastewater. The objective of the present study was to explore the effect of external stimulants, i.e., nutrients, surfactant, and aeration on hydrocarbons degradation potential of CWs. The CWs mesocosms were developed by the vegetation of Phragmites australis and amendments with nutrients (20 mg l−1 N, 2.6 mg l−1 P, and 16.4 mg l−1 K), surfactant Tween 20 (0.2%, v/v), and aeration (7 mg l−1) for the remediation of diesel-spiked water (2%, w/v). The comparative analysis showed that the addition of nutrients, surfactant, and aeration individually enhanced total petroleum hydrocarbons (TPHs) reduction, and maximum TPHs reduction (88.4%) was achieved after 60 days in the mesocosms amended with the combination of nutrients, surfactant, and aeration. Among different individual treatments, the aeration (alone) also played a pivotal role in TPHs reduction (61%). The least (12%) reduction in TPHs was achieved in the mesocosms supplied with surfactant only. This study revealed that the combined application of nutrients, surfactant, and aeration in CWs enhanced its hydrocarbons degradation performance. The biodegradability of crude oil-polluted wastewater is not efficient. It is mainly due to the low bioavailability of hydrocarbons, and less amount of nutrients and dissolved oxygen in the wastewater. This study explores the importance of the amendments of nutrients, surfactant, and aeration on the enhanced performance of constructed wetlands (CWs) for the remediation of hydrocarbon-contaminated water. The application of nutrients, surfactant, and aeration in CWs not only enhanced hydrocarbon degradation and toxicity reduction but also improved plant growth. [ABSTRACT FROM AUTHOR]

Polyploidization and hybridization are very common in natural plant species, and mixed‐ploidy species provide a unique opportunity to study the effects of evolutionary history, local abundance, and ploidy level on the direction and extent of introgression between intraspecific lineages. First, we delimited two morphologically cryptic lineages of Phragmites australis Trin. ex Steud. in temperate China using 11 nuclear microsatellites and two chloroplast DNA fragments with 225 samples from China as well as 11 samples from Oceania and Europe. Our evidence supported that haplotype O and haplotype P were two relatively independent lineages with low and high ploidy levels, respectively; haplotype M might be ancient and could have undergone a complex evolutionary history. Then we examined the lineage divergence and compared the introgression patterns between two major lineages along geographical and abundance gradients with a large number of samples (n = 1067) collected from China. The sympatric coexistence of two lineages in north and northeast China implies an ongoing or potential introgression between them. Cline analysis showed that the level of genetic admixture were significantly correlated with longitude rather than latitude. Our results also suggested that ploidy level could deeply influence the introgression asymmetry, and the effect of the current local abundance on introgression might be covered by the past coexistence time driven by phylogeographic history. Our study draws a baseline for future research on the ecological and evolutionary consequences of migration and introgression of Chinese P. australis under global change. [ABSTRACT FROM AUTHOR]

Background Coastal wetlands are threatened by the increased salinity that may result from sea level rise. Salinity stress alters species zonation patterns through changes in competitive outcome between species differing in salinity tolerance. This study therefore aimed to understand how salinity and light affect two dominant and competing coastal wetland grasses that differ in salt tolerance, height and photosynthetic metabolism. Methods The C4 species Spartina anglica and the C3 species Phragmites australis were grown at five salinity levels (0, 7, 14, 21 and 28 ppt) and two light fluxes (100 % and 50 % of natural daylight) in an outdoor experimental setup for 102 d with full access to nutrients. Key Results Salinity reduced the biomass, height and shoot density of P. australis from 81.7 g dry weight (DW), 0.73 m and 37 shoots per pot at a salinity of 0 ppt to 16.8 gDW, 0.3 m and 14 shoots per pot at a salinity of 28 ppt. Biomass, height and shoot density of S. anglica did not respond or were only slightly reduced at the highest salinity of 28 ppt. High salinity also resulted in a higher tissue concentration of N and P in P. australis. Both species had low ability to acclimate to the lower light flux. Shade acclimation in S. anglica occurred via modest changes in specific leaf area, pigment content and biomass allocation. Conclusions High salinity reduced traits important for light competition and increased the nutrient concentration in P. australis leaf and root biomass, while this was overall unaffected in S. anglica. This is likely to reduce the competitive ability of P. australis over S. anglica for light because at high salinities the former cannot effectively shade the lower-growing S. anglica. Neither species effectively acclimates to shade, which could explain why S. anglica does not occur in the understorey of P. australis at low salinities. [ABSTRACT FROM AUTHOR]

Phragmites australis is a cosmopolitan plant species with high intraspecific diversity and phenotypic plasticity. Due to its variability and large ecological niche breadth, subgroups of P. australis have become invasive in North America, and this invasion has been recognized late. While this cryptic invasion on the American continent has received much attention, little is known about the potential invasiveness of other subgroups, especially within Asian/Australian P. australis. We therefore compared the performance of three subgroups within the Asian/Australian group: a freshwater (CN) and an estuarine (YRD) subgroup collected in China and a genetically closely related subgroup collected from Australia (FEAU), grown in two common gardens in China. Our results showed that the FEAU subgroup had no strong invasive potential, as its total biomass, height, shoot number, specific leaf area, and stomatal conductance were lower than that of the two native subgroups. All three subgroups responded similarly with most traits to the different climates of the gardens, albeit with different response strength, expressed as phenotypic plasticity indices. The potential cryptic invasion risk of the FEAU subgroup in China seems to be low, since its functional traits showed low competitiveness and most traits with the lowest plasticity occurred in FEAU. However, caution is still advised, because other invasive mechanisms, such as enemy release or the performance under extreme environmental conditions were not tested in our study. [ABSTRACT FROM AUTHOR]

Research in natural wetlands as well as constructed wetlands has increased exponentially in the past years, since wet ecosystems can serve as nature-based solutions against the threats posed by climate change. Sequestration of those nutrients in the wetland vegetation can protect surface waters and discharge to the river from nutrient pollution. Preface: Wetland ecosystems - functions and use in a changing climate Guest editors: Franziska Eller, Hans Brix, Brian K. Sorrell & Carlos A. Arias / Wetland ecosystems: functions and use in a changing climate Wetlands, both natural and constructed, provide a wide range of ecological benefits and ecosystem services that include water quality improvement, climate regulation, nutrient processing, carbon sequestration, as well as recreation and habitat improvement. [Extracted from the article]

Soil salinity diminishes the dominance of species and affects their distribution. Phragmites australis is a dominant ecosystem engineer with broad distribution, high intraspecific variation and great socio-economic importance. Coastal ecosystems inhabited by P. australis are threatened by salinization. Here, we investigated salinity tolerance of freshwater and salt marsh population of the species, grown under two soil salinities and in two common gardens. Salinity significantly affected the growth, biomass, leaf physiological parameters and ion concentration. Climate altered morphology and ion concentration of P. australis. In contrast to our hypothesis, the salt marsh population was not more salt tolerant than the freshwater population, and both showed a low degree of salt stress, maintaining their photosynthesis and chlorophyll concentration, and only showing small decreases in biomass and height when salt-treated. We therefore ruled out local adaptation to soil salinity. Instead, both populations acclimated by phenotypic plasticity of biomass, root: shoot ratio, stomatal conductance and ion content. The salinity tolerance strategy of both populations was ion concentration by tissue desiccation, which was most efficient in the drier climate common garden. Hence, plants utilizing tissue desiccation as salinity tolerance strategy will have an advantage in areas where climate change leads to drier air humidity. [ABSTRACT FROM AUTHOR]

Polyploidization in plants is thought to have occurred as coping mechanism with environmental stresses. Polyploidization-driven adaptation is often achieved through interplay of gene networks involved in differentially expressed genes, which triggers the plant to evolve special phenotypic traits for survival. Phragmites australis is a cosmopolitan species with highly variable phenotypic traits and high adaptation capacity to various habitats. The species' ploidy level varies from 3x to 12x, thus it is an ideal organism to investigate the molecular evolution of polyploidy and gene regulation mediated by different numbers of chromosome copies. In this study, we used high-throughput RNAseq data as a tool, to analyze the gene expression profiles in tetraploid and octoploid P. australis. The estimated divergence time between tetraploid and octoploid P. australis was dated to the border between Pliocene and Pleistocene. This study identified 439 up- and 956 down-regulated transcripts in tetraploids compared to octoploids. Gene ontology and pathway analysis revealed that tetraploids tended to express genes responsible for reproduction and seed germination to complete the reproduction cycle early, and expressed genes related to defense against UV-B light and fungi, whereas octoploids expressed mainly genes related to thermotolerance. Most differentially expressed genes were enriched in chaperones, folding catalysts and protein processing in endoplasmic reticulum pathways. Multiple biased isoform usage of the same gene was detected in differentially expressed genes, and the ones upregulated in octoploids were related to reduced DNA methylation. Our study provides new insights into the role of polyploidization on environmental responses and potential stress tolerance in grass species. [ABSTRACT FROM AUTHOR]

Widespread plant species generally have high intraspecific variation in functional traits, which is reflected in their great variety of phenotypes. This variety can result from both genetic differences due to local adaptation and phenotypic plasticity. With high intraspecific variation and nearly global distribution, the common reed Phragmites australis is a suitable model species for studying the underlying mechanisms of intraspecific trait variation.In this study, 71 genotypes of P. australis from seven phylogeographic groups were transplanted into two replicate common gardens located in very different climates: northern Europe and mid‐east Asia. We measured seven functional traits of all these genotypes over the growing season, including shoot height, maximum biomass per shoot, shoot density, node number per stem, leaf life span, flowering occurrence and flowering date. Our aim was to assess the relative effects of genetic (phylogeographic origin) and environmental (common garden) status, and interactions between them, on intraspecific variation in functional traits of P. australis.We found common garden having the strongest influence on most functional traits studied. All traits except flowering occurrence varied significantly across gardens, revealing the important role of phenotypic plasticity on trait variation in P. australis. We also found significant differences in trait variation among the different phylogeographic groups of P. australis and, thus, evidence for genetically determined intraspecific variation in the morphological and life‐history traits addressed in this study. All functional traits showed significant (p ≤ 0.0054), albeit minor to moderately explained (R2 ≤ 0.57), latitudinal patterns in both gardens. Covariation of multiple traits was similar in the two gardens. Phenotypic plasticity was trait‐ specific, and the plasticity of shoot height and maximum biomass per shoot increased towards higher latitude of genotypic origin. Our results indicate that the latitude of origin affects the evolution of functional traits, as well as their phenotypic plasticity.Since phenotypic plasticity is a crucial mechanism for acclimation and evolution, our findings support the role of gene‐based adaptive phenotypic plasticity in plant evolution. The intraspecific spatial variation in functional traits and their phenotypic plasticity can help predict species distribution, persistence and invasion under global climate change. [ABSTRACT FROM AUTHOR]

Identifying the factors that influence spatial genetic structure among populations can provide insights into the evolution of invasive plants. In this study, we used the common reed (Phragmites australis), a grass native in Europe and invading North America, to examine the relative importance of geographic, environmental (represented by climate here), and human effects on population genetic structure and its changes during invasion. We collected samples of P. australis from both the invaded North American and native European ranges and used molecular markers to investigate the population genetic structure within and between ranges. We used path analysis to identify the contributions of each of the three factors—geographic, environmental, and humanrelated—to the formation of spatial genetic patterns. Genetic differentiation was observed between the introduced and native populations, and their genetic structure in the native and introduced ranges was different. There were strong effects of geography and environment on the genetic structure of populations in the native range, but the human-related factors manifested through colonization of anthropogenic habitats in the introduced range counteracted the effects of environment. The between-range genetic differences among populations were mainly explained by the heterogeneous environment between the ranges, with the coefficient 2.6 times higher for the environment than that explained by the geographic distance. Human activities were the primary contributor to the genetic structure of the introduced populations. The significant environmental divergence between ranges and the strong contribution of human activities to the genetic structure in the introduced range suggest that invasive populations of P. australis have evolved to adapt to a different climate and to human-made habitats in North America. [ABSTRACT FROM AUTHOR]

The literature suggests that small genomes promote invasion in plants, but little is known about the interaction of genome size with other traits or about the role of genome size during different phases of the invasion process. By intercontinental comparison of native and invasive populations of the common reed Phragmites australis, we revealed a distinct relationship between genome size and invasiveness at the intraspecific level. Monoploid genome size was the only significant variable that clearly separated the North American native plants from those of European origin. The mean Cx value (the amount of DNA in one chromosome set) for source European native populations was 0.490 ± 0.007 (mean ± SD), for North American invasive 0.506 ± 0.020, and for North American native 0.543 ± 0.021. Relative to native populations, the European populations that successfully invaded North America had a smaller genome that was associated with plant traits favoring invasiveness (long rhizomes, early emerging abundant shoots, resistance to aphid attack, and low C:N ratio). The knowledge that invasive populations within species can be identified based on genome size can be applied to screen potentially invasive populations of Phragmites in other parts of the world where they could grow in mixed stands with native plants, as well as to other plant species with intraspecific variation in invasion potential. Moreover, as small genomes are better equipped to respond to extreme environmental conditions such as drought, the mechanism reported here may represent an emerging driver for future invasions and range expansions. [ABSTRACT FROM AUTHOR]

We aimed at assessing the effects of four wetland plant species commonly used in constructed wetland systems: Typha, Phragmites, Iris and Juncus for removing ibuprofen (IBU) and iohexol (IOH) from spiked culture solution and exploring the mechanisms responsible for the removal. IBU was nearly completely removed by all plant species during the 24-day experiment, whereas the IOH removal varied between 13 and 80 %. Typha and Phragmites were the most efficient in removing IBU and IOH, respectively, with first-order removal rate constants of 0.38 and 0.06 day, respectively. The pharmaceuticals were taken up by the roots and translocated to the aerial tissues. However, at the end of the experiment, plant accumulation constituted only up to 1.1 and 5.7 % of the amount of IBU and IOH spiked initially. The data suggest that the plants mainly function by facilitating pharmaceutical degradation in the rhizosphere through release of root exudates. [ABSTRACT FROM AUTHOR]

Compared with non-invasive species, invasive plant species may benefit from certain advantageous traits, for example, higher photosynthesis capacity and resource/energy-use efficiency. These traits can be preadapted prior to introduction, but can also be acquired through evolution following introduction to the new range. Disentangling the origins of these advantageous traits is a fundamental and emerging question in invasion ecology. We conducted a multiple comparative experiment under identical environmental condition with the invasive haplotype M lineage of the wetland grass Phragmites australis and compared the ecophysiological traits of this invasive haplotype M in North America with those of the European ancestor and the conspecific North American native haplotype E lineage, P. australis ssp. americanus. The invasive haplotype M differed significantly from the native North American conspecific haplotype E in several ecophysiological and morphological traits, and the European haplotype M had a more efficient photosynthetic apparatus than the native North American P. australis ssp. americanus. Within the haplotype M lineage, the introduced North American P. australis exhibited different biomass allocation patterns and resource/energy-use strategies compared to its European ancestor group. A discriminant analysis of principal components separated the haplotype M and the haplotype E lineages completely along the first canonical axis, highly related to photosynthetic gas-exchange parameters, photosynthetic energy-use efficiency and payback time. The second canonical axis, highly related to photosynthetic nitrogen use efficiency and construction costs, significantly separated the introduced P. australis in North America from its European ancestor. Synthesis. We conclude that the European P. australis lineage was preadapted to be invasive prior to its introduction, and that the invasion in North America is further stimulated by rapid post-introduction evolution in several advantageous traits. The multicomparison approach used in this study could be an effective approach for distinguishing preadaptation and post-introduction evolution of invasive species. Further research is needed to link the observed changes in invasive traits to the genetic variation and the interaction with the environment. [ABSTRACT FROM AUTHOR]

* Premise of the study: Long-distance dispersal can affect speciation processes in two opposing ways. Dispersal can promote geographic isolation or it can bring together geographically distant and distantly related genotypes, thus counteracting local differentiation. We used the Gulf Coast of North America (GC), a "hot spot" of reed diversity and evolutionary dynamics, as a model system to study the diversification processes within the invasive, cosmopolitan, polyploid grass Phragmites . * Methods: Genetic diversity was studied using collections representing all species of the genus and from all continents (except Antarctica). A range of molecular markers, including chloroplast and nuclear sequences, microsatellites, and AFLPs, was analyzed to detect DNA variation from the population to the species level and to infer phylogenetic relationships across continents. * Key results: An interspecific hybrid, Phragmites mauritianus x P. australis, and four P. australis cp-DNA haplotypes from Africa, Europe, and North America have been dispersed to the GC and interbreed with each other. * Conclusions: Long-distance dispersal and weak breeding barriers appear to be recurring phenomena, not only in the GC, but worldwide. We present data strongly suggesting that interspecific hybridization and introgression among different Phragmites species take place and appear to have contributed significantly to the diversification processes within the genus. Hence, the application of traditional species concepts within Phragmites might be inappropriate. [ABSTRACT FROM AUTHOR]

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in water and sediments of seven wet detention ponds receiving urban stormwater were investigated. The ponds comprised traditional wet detention ponds with a permanent wet volume and a storage volume as well as ponds that were expanded with sand filters and other means to improve the removal of micropollutants. The concentrations of ΣPAH in the sediments varied between 6± 5 and 2,222±603 ng g-1 dry weight (mean±standard deviation), and were highest in the ponds with lower pond volume per catchment area and did not clearly reflect different activities in the catchments. In general, the concentrations of PAHs in the sediments decreased from inlet to outlet, especially in the systems with good conditions for sedimentation such as systems with flow perpendicular sand dikes and extensive submerged vegetation. High molecular weight PAHs were predominant in the sediments indicating the pyrogenic origin of the PAHs. There was no correlation between PAH species concentrations in water or sediments and their hydrophobicity (log Kow). PAH concentrations in water fluctuated in response to intensity and frequency of rain events, whereas concentrations in the sediments integrated the pollutant load over time. Pond systems expanded with sand filters and other technologies to enhance removal of micropollutants consistently had concentrations of PAHs in the effluents below the detection level. [ABSTRACT FROM AUTHOR]

• Internal pressurization and convective gas flow, which can aerate wetland plants more efficiently than diffusion, are common in temperate species. Here, we present the first survey of convective flow in a range of tropical plants. • The occurrence of pressurization and convective flow was determined in 20 common wetland plants from the Mekong Delta in Vietnam. The diel variation in pressurization in culms and the convective flow and gas composition from stubbles were examined for Eleocharis dulcis, Phragmites vallatoria and Hymenachne acutigluma, and related to light, humidity and air temperature. • Nine of the 20 species studied were able to build up a static pressure of > 50 Pa, and eight species had convective flow rates higher than 1 ml min)1. There was a clear diel variation, with higher pressures and flows during the day than during the night, when pressures and flows were close to zero. • It is concluded that convective flow through shoots and rhizomes is a common mechanism for below-ground aeration of tropical wetland plants and that plants with convective flow might have a competitive advantage for growth in deep water. [ABSTRACT FROM AUTHOR]

The potential of using the biomass of four wetland plant species (Iris pseudacorus, Juncus effusus, Phragmites australis and Typha latifolia) grown in treatment wetland systems and under natural conditions were tested to produce high-value materials using hydro-thermal liquefaction (HTL). The results show that the wetland plants biomass is suitable for biocrude and biochar production regardless of the origin. The hydrothermal liquefaction products' (biocrude, biochar, aqueous and gaseous phase) yields vary according with the specific biomass composition of the species. Furthermore, the results show that the biomass composition can be affected by the growing condition (treatment wetland or natural unpolluted conditions) of the plants. None of the single components seems to have a determinant effect on the biocrude yields, which reached around 30% for all the analyzed plants. On the contrary, the biochar yields seem to be affected by the composition of the biomass, obtaining different yields for the different plant species, with biochar yields values from around 12% to 22%, being that Phragmites australis is the one with the highest average yield. The obtained aqueous phase from the different plant species produces homogeneous compounds for each plant species and each growing environment. The study shows that biomass from treatment wetlands is suitable for biocrude production. The environmental value of this biomass lies on the fact that it is considered a residual product with no aggregated value. The treatment wetland biomass is a potential sustainable source for biofuel production since these plants do not need extra land or nutrients for growing, and the biomass does not compete with other uses, offering new sources for enhancing the bioeconomy concepts. [ABSTRACT FROM AUTHOR]

Abstract: Official guidelines for the on-site treatment of domestic sewage have recently been published by the Danish Ministry of Environment as a consequence of new treatment requirements for single houses and dwellings in rural areas. This paper summarises the guidelines for vertical constructed wetland systems (planted filter beds) that will fulfil demands of 95% removal of BOD and 90% nitrification. The system can be extended with chemical precipitation of phosphorus with aluminium polychloride in the sedimentation tank to meet requirements of 90% phosphorus removal. The necessary surface area of the filter bed is 3.2m2/person equivalent and the effective filter depth is 1.0m. The filter medium must be filtersand with a d 10 between 0.25 and 1.2mm, a d 60 between 1 and 4mm, and a uniformity coefficient (U = d 60/d 10) less than 3.5. The sewage is, after sedimentation, pulse-loaded onto the surface of the bed using pumping and a network of distribution pipes. The drainage layer in the bottom of the bed is passively aerated through vertical pipes extending into the atmosphere in order to improve oxygen transfer to the bed medium. Half of the nitrified effluent from the filter is recirculated to the first chamber of the sedimentation tank or to the pumping well in order to enhance denitrification and to stabilise the treatment performance of the system. A phosphorus removal system is installed in the sedimentation tank using a small dosing pump. The mixing of chemicals is obtained by a simple airlift pump, which also circulates water in the sedimentation tank. The vertical flow constructed wetland system is an attractive alternative to the common practice of soil infiltration and provides efficient treatment of sewage for discharge into the aquatic environment. [Copyright &y& Elsevier]

Intraspecific trait variation, essential to Darwin's mechanism of natural selection, has been widely examined for single characters. However, intraspecific variation of adaptive strategies which represent trade‐offs among multiple functional traits has received less attention, particularly for species that are globally distributed or invasive. Grime's competitor, stress tolerator and ruderal (CSR) scheme, well validated in the context of alien species invasions, provides both the theory and quantitative methodology to investigate adaptive strategies. Here, we quantified the intraspecific CSR strategy scores of a worldwide collection of 89 Phragmites australis genotypes which were cultivated in a common garden. We assessed the relationships between intraspecific variation in CSR strategy scores, genome size and climate of origin and tested whether the invasive and native lineages differ in CSR strategies. Substantial variation in intraspecific adaptive strategy, characterized mainly in C‐ and S‐selection, was observed. As expected, C‐, S‐ and R‐scores showed clear latitudinal clines and were strongly related to either genome size or climate of origin. Furthermore, invasive lineages were more stress adapted than native lineages. We conclude that the adaptive strategy of this perennial wetland grass varies globally, and its genotypes are surprisingly more stress tolerant in the invaded range where it was first detected ~150 years ago. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

We collected and analyzed morphological characteristics and tissue nutrient concentrations of common reed (Phragmites australis) populations from Denmark, USA, and China, harvested late summer at the peak of the biomass production. The aim was to estimate the suitability of the biomass for different bioenergy purposes. The potential of reed as bioenergy feedstock is increasingly recognized, as the species already is utilized for construction, water purification, and pulp production. Our morphological data showed that biomass yield can be allometrically predicted to be high, especially in the reed populations of the US. However, no consistent pattern according to geographical origin was detected, and especially tissue nutrient concentrations varied within and between populations. Some mineral concentrations were above the desirable threshold for biocombustion, such as nitrogen (N) and sulfur (S). Iron (Fe) was higher than the critical toxicity concentration in many populations and hence, negatively correlated with morphological and growth traits. A different harvest time is likely to result in lower ion concentrations. Some populations had low C to N ratios, which are suitable for biomethane production, while the relatively low ash content of all populations (ranging from 3.9% to 8.5%) suggested a high heating value and theoretical energy potential. Reed biomass production is a promising alternative to fossil fuels and potentially suitable for other bio-based product. Improved knowledge is needed to examine local needs and application possibilities for reed biomass. [ABSTRACT FROM AUTHOR]

Abstract: The effect of NH4 +/NO3 − availability on nitrate reductase (NR) activity in Phragmites australis and Glyceria maxima was studied in sand and water cultures with the goal to characterise the relationship between NR activity and NO3 − availability in the rhizosphere and to describe the extent to which NH4 + suppresses the utilization of NO3 − in wetland plants. The NR activity data showed that both wetland helophytes are able to utilize NO3 −. This finding was further supported by sufficient growth observed under the strict NO3 − nutrition. The distribution of NR activity within plant tissues differed between species. Phragmites was proved to be preferential leaf NO3 − reducer with high NR activity in leaves (NRmax >6.5μmol NO2 − gdrywt−1 h−1) under all N treatments, and therefore Phragmites seems to be good indicator of NO3 − availability in flooded sediment. In the case of Glyceria the contribution of roots to plant NO3 − reduction was higher, especially in sand culture. Glyceria also tended to accumulate NO3 − in non-reduced form, showing generally lower leaf NR activity levels. Thus, the NR activity does not necessarily correspond with plant ability to take up NO3 − and grow under NO3 −-N source. Moreover, the species differed significantly in the content of compounds interfering with NR activity estimation. Glyceria, but not Phragmites, contained cyanogenic glycosides releasing cyanide, the potent NR inhibitor. It clearly shows that the use of NR activity as a marker of NO3 − utilization in individual plant species is impossible without the precise method optimisation. [Copyright &y& Elsevier]

Abstract: The effects of NH4 + or NO3 − on growth, resource allocation and nitrogen (N) uptake kinetics of two common helophytes Phragmites australis (Cav.) Trin. ex Steudel and Glyceria maxima (Hartm.) Holmb. were studied in semi steady-state hydroponic cultures. At a steady-state nitrogen availability of 34μM the growth rate of Phragmites was not affected by the N form (mean RGR=35.4mgg−1 d−1), whereas the growth rate of Glyceria was 16% higher in NH4 +-N cultures than in NO3 −-N cultures (mean=66.7 and 57.4mgg−1 d−1 of NH4 + and NO3 − treated plants, respectively). Phragmites and Glyceria had higher S/R ratio in NH4 + cultures than in NO3 − cultures, 123.5 and 129.7%, respectively. Species differed in the nitrogen utilisation. In Glyceria, the relative tissue N content was higher than in Phragmites and was increased in NH4 + treated plants by 16%. The tissue NH4 + concentration (mean=1.6μmolgfreshwt−1) was not affected by N treatment, whereas NO3 − contents were higher in NO3 − (mean=1.5μmolgfreshwt−1) than in NH4 + (mean=0.4μmolgfreshwt−1) treated plants. In Phragmites, NH4 + (mean=1.6μmolgfreshwt−1) and NO3 − (mean=0.2μmolgfreshwt−1) contents were not affected by the N regime. Species did not differ in NH4 + (mean=56.5μmolg−1 root dry wth−1) and NO3 − (mean=34.5μmolg−1 root dry wth−1) maximum uptake rates (V max), and V max for NH4 + uptake was not affected by N treatment. The uptake rate of NO3 − was low in NH4 + treated plants, and an induction phase for NO3 − was observed in NH4 + treated Phragmites but not in Glyceria. Phragmites had low K m (mean=4.5μM) and high affinity (10.3lg−1 root dry wth−1) for both ions compared to Glyceria (K m =6.3μM, affinity=8.0lg−1 root dry wth−1). The results showed different plasticity of Phragmites and Glyceria toward N source. The positive response to NH4 +-N source may participates in the observed success of Glyceria at NH4 + rich sites, although other factors have to be considered. Higher plasticity of Phragmites toward low nutrient availability may favour this species at oligotrophic sites. [Copyright &y& Elsevier]

[Display omitted] • Species and genetic diversity restrain litter decomposition in the costal wetland. • Functional diversity could predict decomposition at species and genetic levels. • Specific component could affect non-additive effects at species and genetic levels. With the enhancement of carbon sink capacity and the intensification of biodiversity change in coastal wetlands, previous studies have well studied the relationship between species diversity and litter decomposition, a vital process of carbon cycling. However, previous studies ignored the importance of genetic diversity, which restricted our comprehensive understanding of the effects of biodiversity loss on ecosystem functions. Here, we manipulated different richness levels with litters of eight common species of coastal wetland plants and eight different genotypes of common reed (Phragmites australis) to explore the effects of species and genetic diversity on litter decomposition. We found the litter mass loss of mixtures was significantly lower than the average mass loss of single litters (ANOVA, p < 0.05), suggesting higher species and genetic diversity had negative effects on plant litter decomposition. The negative effects were also supported by the t -test that the observed mass loss was significantly lower than expected at both species and genetic diversity levels, which also identified that antagonistic effects occurred. In addition, the functional diversity of initial litter qualities, such as lignin content and the C/P ratio, had a significant correlation with the negative effects at species and genetic levels, whereas phylogenetic diversity did not reveal such a correlation, implying functional diversity might better predict the effects of diversity changes on litter decomposition in coastal wetlands at both species and genetic levels. Furthermore, the presence of specific species or genotype litters, such as Scorzonera mongolica, Imperata cylindrica and the common reed numbered CN2026, could also predict negative effects. In this study, we found that genetic diversity influenced litter decomposition as much as species diversity, and we provided significant implications for predicting the effect of wetland biodiversity loss or conservation on carbon sink capacity. [ABSTRACT FROM AUTHOR]

Abstract: The Sludge Treatment Reed Bed (STRB) technology is a cost-efficient and environmentally friendly technology to dewater and mineralize surplus sludge from conventional wastewater treatment systems. Primary and secondary liquid sludge is loaded onto the surface of the bed over several years, where it is dewatered, mineralized and turned into a biosolid with a high dry matter content for use as an organic fertilizer on agricultural land. We analysed the concentrations of five organic micropollutants (galaxolide, tonalide, cashmeran, celestolide and DEHP) and six heavy metals (Pb, Ni, Cu, Cd, Zn and Cr) in the accumulated sludge in a 20-year old STRB in Denmark in order to assess the degradation and fate of these contaminants in a STRB and the relation to sludge composition. The results showed that the deposited sludge was dewatered to reach a dry matter content of 29%, and that up to a third of the organic content of the sludge was mineralized. The concentrations of heavy metals generally increased with depth in the vertical sludge profile due to the dewatering and mineralization of organic matter, but in all cases the concentrations were below the European Union legal limits for agricultural land disposal. The concentrations of fragrances and DEHP ranged from 10 to 9000 ng g−1 dry mass. The attenuation of hydrophobic micropollutants from the top to the bottom layer of the reed bed ranged from 40 to 98%, except for tonalide which increased significantly with sludge depth, and consequently showed an unusual depth distribution of the galaxolide/tonalide ratio. This unexpected pattern may reflect changes imposed by a long storage time and/or different composition of the fresh sludge in the past. The lack of a significant decreasing DEHP concentration with sludge age might indicate that this compound is very persistent in STRBs. In conclusion the STRB was a feasible technology for sludge treatment before its land disposal. [Copyright &y& Elsevier]

Abstract: The treatment capacity of constructed wetlands is expected to be high in tropical areas because of the warm temperatures and the associated higher rates of microbial activity. A pilot scale horizontal subsurface flow constructed wetland system filled with river sand and planted with Phragmites vallatoria (L.) Veldkamp was set up in the southern part of Vietnam to assess the treatment capacity and the removal rate kinetics under tropical conditions. The system received municipal wastewater at four hydraulic loading rates (HLRs) of 31, 62, 104 and 146mmday−1. Removals of TSS, BOD5 and COD were efficient at all HLRs with mean removal rates of 86–95%, 65–83% and 57–84%, respectively. Removals of N and P decreased with HLRs and were: NH4-N 0–91%; TN 16–84% and TP 72–99%. First-order area-based removal rate constants (k, myear−1) estimated from sampling along the length of the wetland from inlet to outlet at the four HLRs were in the range of 25–95 (BOD5), 22–30 (COD), 31–115 (TSS), 5–24 (TN and TKN) and 41–84 (TP) at background concentrations (C*) of 5, 10, 0, 1.5 and 0mgL−1, respectively. The estimated k-values should not be used for design purposes, as site-specific differences and stochastic variability can be high. However, the study shows that domestic wastewater can be treated in horizontal subsurface flow constructed wetland systems to meet even the most stringent Vietnamese standards for discharge into surface waters. [Copyright &y& Elsevier]

Abstract: The ability to cope with NH4 +-N was studied in the littoral helophytes Phragmites australis and Glyceria maxima, species commonly occupying fertile habitats rich in NH4 + and often used in artificial wetlands. In the present study, Glyceria growth rate was reduced by 16% at 179μM NH4 +-N, and the biomass production was reduced by 47% at 3700μM NH4 +-N compared to NO3 −-N. Similar responses were not found in Phragmites. The amounts (mgg−1 drywt) of starch and total non-structural carbohydrates (TNC) in rhizomes were significantly lower in NH4 + (8.9; 12.2 starch; 20.1; 41.9 TNC) compared to NO3 − treated plants (28.0; 15.6 starch; 58.5; 56.3 TNC) in Phragmites and Glyceria, respectively. In addition, Glyceria showed lower amounts (mgg−1 drywt) of soluble sugars, TNC, K+, and Mg2+ in roots under NH4 + (5.6; 14.3; 20.6; 1.9) compared to NO3 − nutrition (11.6; 19.9; 37.9; 2.9, for soluble sugars, TNC, K+, and Mg2+, respectively), while root internal levels of NH4 + and Ca2+ (0.29; 4.6mgg−1 drywt, mean of both treatments) were only slightly affected. In Phragmites, no changes in soluble sugars, TNC, Ca2+, K+, and Mg2+ contents of roots (7.3; 14.9; 5.1; 17.3; 2.6mgg−1 drywt, means of both treatments) were found in response to treatments. The results, therefore, indicate a more pronounced tolerance towards high NH4 + supply in Phragmites compared to Glyceria, although the former may be susceptible to starch exhaustion in NH4 +-N nutrition. In contrast, Glyceria''s ability to colonize fertile habitats rich in NH4 + is probably related to the avoidance strategy due to shallow rooting or to the previously described ability to cope with high NH4 + levels when P availability is high and NO3 − is also provided. [Copyright &y& Elsevier]