Wetland Plant Species Research Articles

Impact of Extreme Drought on Vegetation Greenness in Poyang Lake Wetland

The Poyang Lake Wetland, an internationally significant ecosystem, frequently experiences drought during the flood season. However, the total impact of extreme drought on wetland vegetation remains poorly understood. This study determined the standardised precipitation evapotranspiration index (SPEI) and analysed drought trends within the Poyang Lake Basin. Additionally, spatiotemporal variations in wetland vegetation under drought conditions were examined by analysing the mean normalised difference vegetation index (NDVI) values and categorising NDVI classifications. The key factors affecting wetland vegetation and its respective thresholds were determined. The Poyang Lake Basin has experienced increasing aridity over the past 3 years. In response to this trend, the wetland vegetation area in Poyang Lake expanded, whereas vegetation greenness declined. Notably, in the year following an extreme drought, Poyang Lake’s vegetation greenness was lower than that during the same period in previous years. Regardless, the correlation analysis showed no significant relationship between the SPEI values and the wetland vegetation greenness; however, water level changes significantly impacted the wetland vegetation, with a correlation coefficient of −0.89 (p < 0.001). A critical water level of 14 m was identified as the threshold at which sudden changes in the mean NDVI were observed. This research offers valuable insights into hydrological management strategies to protect Poyang Lake Wetland’s vegetation under drought conditions. Future studies should enhance the differentiation of drought tolerance among different wetland plant species, thereby achieving differentiated hydrological management.

Wetland plant species and biochar amendments lead to variable salinity reduction in roadway-associated soils

Salinization is an emerging threat in freshwater wetlands, with few techniques available to mitigate anthropogenic inputs such as road salts. Phytoremediation and biochar addition have each been proposed to remediate salt-affected soils generally, but interactive effects in wetland environments to improve soil conditions adjacent to roadways are not well understood. We conducted an 88-day fully factorial greenhouse experiment to quantify the effects of three plant treatments (unvegetated, Typha × glauca and Phragmites australis) and three biochar rates (0.0, 2.5, 5.0 % wt/wt) on the soil and leachate of a simulated wetland system. Both plant species significantly reduced soil Cl− content relative to unvegetated controls, while Typha also significantly reduced Cl− content of leachate and soil Na+. The difference in effects was likely due to different salt tolerance strategies: the salt-accumulating Typha contained a significantly higher volume of Na+, Cl−, and water in its tissue than Phragmites, whose greater K+:Na+ ratio and similar soil Na+ to controls indicated a salt exclusion strategy. Biochar did not influence the growth of either species but moderately increased tissue Na+ concentration in Typha. Furthermore, biochar's effects on soil and leachate salt levels varied by application rate with the medium rate moderately increasing soil Na+ and Cl− and leachate Cl−, while the highest application did not differ from controls across all metrics. Our results suggest that phytoremediation can be optimized with salt-accumulating species, whose mechanisms of salt tolerance involve the accumulation of salt ions from the surrounding environment. The consistent flooding in our study may have inhibited the influence of biochar. We recommend future studies parse the effects of water levels and redox potential on biochar's ability to influence wetland salinity.Data repository: doi.org/10.17605/OSF.IO/9QFZ7

Float, fly, then sink: wetland plant seed buoyancy is lost after internal dispersal by waterbirds

Seed dispersal distance is an important indicator of how well a plant species can cope with environmental changes. Seeds of wetland plants are primarily dispersed by hydrochory (floating on the water surface) or endozoochory (ingestion and egestion by animals). However, both mechanisms can also be combined (diplochory), which increases dispersal distances. In wetlands, seeds often float on the water surface before ingestion and transport by animals, such as waterbirds. Here, we consider what happens next after endozoochory and test whether seeds dispersed inside waterbirds can then continue to disperse by hydrochory. We experimentally assessed the buoyancy capacity of 41 wetland plant species for 14 weeks before and after simulated passage through avian digestive systems. This revealed that (1) seeds of plants previously assigned a hydrochory dispersal syndrome floated longer than those from other syndromes, but with considerable overlap; (2) fully aquatic and shoreline plant species had seeds with stronger buoyancy than terrestrial plants; and (3) digestive processes negatively affected seed buoyancy capacity for all plant species, which included wetland species with a typical hydrochory syndrome. The capacity for hydrochory is more limited after endozoochory than beforehand, with strong implications for the effectiveness of seed dispersal.

Large-scale geographic patterns and environmental and anthropogenic drivers of wetland plant diversity in the Qinghai-Tibet Plateau

BackgroundThe geographic patterns of plant diversity in the Qinghai-Tibet Plateau (QTP) have been widely studied, but few studies have focused on wetland plants. This study quantified the geographic patterns of wetland plant diversity in the QTP through a comprehensive analysis of taxonomic, phylogenetic and functional indices.MethodsBased on a large number of floras, monographs, specimens and field survey data, we constructed a comprehensive dataset of 1,958 wetland plant species in the QTP. Species richness (SR), phylogenetic diversity (PD), functional diversity (FD), net relatedness index (NRI) and net functional relatedness index (NFRI) were used to assess the taxonomic, phylogenetic and functional diversity of wetland plants. We explored the relationships between the diversity indices and four categories of environmental variables (i.e. energy-water, climate seasonality, topography and human activities). We used four diversity indices, namely endemic species richness, weighted endemism, phylogenetic endemism and functional endemism, together with the categorical analysis of neo- and paleo-endemism (CANAPE), to identify the endemic centers of wetland plants in the QTP.ResultsSR, PD and FD were highly consistent and showed a decreasing trend from southeast to northwest, decreasing with increasing elevation. The phylogenetic structure of wetland plant assemblages in most parts of the plateau is mainly clustered. The functional structure of wetland plant assemblages in the southeast of the plateau is overdispersed, while the functional structure of wetland plant assemblages in other areas is clustered. Energy-water and climate seasonality were the two most important categories of variables affecting wetland plant diversity. Environmental variables had a greater effect on the functional structure of wetland plants than on the phylogenetic structure. This study identified seven endemic centres, mainly in the Himalayas and Hengduan Mountains.ConclusionsClimate and topography are the main factors determining the geographic distribution of wetland plant diversity at large scales. The majority of grid cells in the QTP with significant phylogenetic endemism were mixed and super-endemism. At large scales, compared to climate and topography, human activities may not have a negative impact on wetland plant diversity in the QTP.

Re-watering solution facilitates seed germination and seedling growth of Carex schmidtii: Implication for species re-introduction in degraded semi-arid wetlands

Water deficiency threatens the health and function of wetlands in semi-arid areas. Optimum re-watering is an effective method for close-to-natural restoration to mitigate wetland degradation. Although the ecological importance of optimal re-watering as a nature-based solution for promoting wetland plant growth has been widely recognized, the response mechanisms of seed germination and seedling growth to re-watering are still poorly understood despite their decisive impact on plant life history. To fill this gap, this study compared the characteristics of seed germination and seedling growth in Carex schmidtii under initial water content with three levels (30%, 50%, and 70%) and five re-watering treatments (maintained at constant water content and re-watering to 100% on 7th, 14th, 21st, and 28th day). Moreover, the degree of reserve mobilization during four germination stages (seed suckering, sprouting, 20% germination, and seedling growth) was investigated. The results showed that water deficiency and re-watering treatments significantly affected C. schmidtii seed germination, seedling growth, and reserve mobilization. Compared with the other treatments, 50% moisture content and re-watering to 100% on the 14th day (50%-RT3) treatment significantly improved germination traits (germination rate, daily germination rate, germination index, and vigor index) and seedling growth characteristics (shoot length, root length, shoot biomass, root biomass, and total biomass). Furthermore, the degree of mobilization of starch, soluble protein, fat, and soluble sugar accumulation in C. schmidtii seeds under 50%-RT3 was higher than that in the other treatments. The structural equation model showed that the characteristics of seed germination and seedling growth of C. schmidtii were directly related to water deficiency and re-watering treatments, whereas reserve mobilization indirectly affected seed germination and seedling growth. These findings demonstrated that water deficiency and re-watering treatments have a crucial regulatory effect on seed germination and seedling growth of wetland plant species through a dual mechanism. This study provides information for the formulation of an optimum re-watering strategy for wetland vegetation restoration in semi-arid areas of the world.

Potential of biochar and humic substances for phytoremediation of trace metals in oil sands process affected water

Oil sands process affected water (OSPW) is produced during bitumen extraction and typically contains high concentrations of trace metals. Constructed wetlands have emerged as a cost effective and green technology for the treatment of metals in wastewaters. Whether the addition of amendments to constructed wetlands can improve metal removal efficiency is unknown. We investigated the synergistic effects of carbon based amendments and wetland plant species in removal of arsenic, cadmium, cobalt, chromium, copper, nickel, and selenium from OSPW. Three native wetland species (Carex aquatilis, Juncus balticus, Scirpus validus) and two amendments (canola straw biochar, nano humus) were investigated in constructed wetland mesocosms over 60 days. Amendment effect on metal removal efficiency was not significant, while plant species effect was. Phytoremediation resulted in removal efficiencies of 78.61–96.31 % for arsenic, cadmium, and cobalt. Carex aquatilis had the highest removal efficiencies for all metals. Amendments alone performed well in removing some metals and were comparable to phytoremediation for cadmium, cobalt, copper, and nickel. Metals were primarily distributed in roots with negligible translocation to shoots. Our work provides insights into the role of plants and amendments during metal remediation and their complex interactions in constructed treatment wetlands.

Using resampled nSight-2 hyperspectral data and various machine learning classifiers for discriminating wetland plant species in a Ramsar Wetland site, South Africa

Mapping wetland ecosystems at the species level provides critical information for understanding the nutrient cycle, carbon sequestration, retention and purification of water, waste treatment and pollution control. However, wetland ecosystems are threatened by climate variability and change and anthropogenic activities; thus, their assessment and monitoring have become critical to inform proper management interventions. Contemporary studies show that satellite-based Earth observation (EO) has significant potential for achieving this task. While many multispectral EO data are freely and readily available, its broad spectral bands limit its utility in differentiating subtle differences among similar plant species. In contrast, hyperspectral data has a high spectral resolution, which is superior in discerning minute differences in similar plant species. However, this data is associated with high dimensionality and multicollinearity, which negatively affect the performance of traditional, parametric classification algorithms. To this end, machine algorithms are often preferred to classify hyperspectral data due to their robustness to various data distributions and noise. The current study compared the performance of three advanced machine learning classifiers, i.e., Support Vector Machine (SVM), Random Forest (RF), and Partial Least Squares Discriminant Analysis (PLS-DA), in discriminating four dominant wetland plant species, i.e., Crocosmia sp., Grasses, Agapanthus sp. and Cyperus sp. using simulated hyperspectral data from an upcoming sensor, i.e., nSight-2. The results revealed that SVM is superior, with an overall accuracy of 93.18% (and class-wise accuracies > 85%). In comparison, there were minor differences in the performances of RF and PLS-DA, i.e., 84.09% and 83.63%, respectively. Overall, the results demonstrated that all the evaluated classifiers could achieve acceptable mapping accuracies. However, SVM is more robust, providing exceptional accuracies, and should be considered for operational mapping once the sensor is in space.

Assessment of sulfamethoxazole removal by three wetland plant species under hydroponic conditions: uptake, accumulation, and physiological responses

Plants play a crucial role as a removal pathway in constructed wetlands, demonstrating the ability to absorb and tolerate antibiotics from wastewater. However, the specific contribution of plants in this regard has not yet to be sufficiently established. To gain a more comprehensive insight into the associated processes, we selected three common wetland plant species, Canna indica L. (C. indica), Cyperus alternifolius L. (C. alternifolius), and Thalia dealbata Fraser (T. dealbata), to evaluate their capacity for uptake, accumulation, and physiological response in the removal of sulfamethoxazole (SMX) at varying initial concentrations (10, 30, 100, and 300 µg/L) under hydroponic conditions. The results showed that SMX removal was more efficient at lower concentrations (10 and 30 µg/L) than at higher concentrations (100 and 300 µg/L). Moreover, plant systems were found to consistently outperform unplanted systems in SMX removal. Among the assessed species, C. indica was identified as being relatively effective in the removal of SMX, whereas the performance of C. alternifolius was notably less pronounced. A positive correlation was observed between the concentration of SMX in the plant tissues and that in the external aqueous medium. However, plant tissue residues contributed only a minor fraction to the overall removal of SMX. Wetland plants absorb SMX through their roots, and we accordingly detected significantly higher concentrations in submerged plant tissues. Furthermore, we also detected reductions in net photosynthetic rates indicative of potential phytotoxicity, which is associated with the accumulation of antibiotic in the shoot tissues. Accumulation of SMX in the roots and rhizomes was also found to be associated with the development of shorter roots, with this effect becoming more pronounced with an increase in the concentration of exogenous SMX. However, despite these adverse effects, plants can detoxify antibiotics via the glutathione pathway. Of the assessed plant species, C. indica was identified as the most SMX tolerant, as indicated by K m and V max values, with C. alternifolius being the least tolerant. Our findings in this study reveal the potential value of wetland plants in the sequestration of antibiotics and provide evidence for the underlying mechanisms of action. These findings could make an important contribution to the implementation of phytoremediation in antibiotic-contaminated water.

Plant distribution and conservation in mediterranean islands’ lentic wetlands: there is more than aquatic species

This study investigates the distribution and conservation status of plant species in lentic wetlands of Mediterranean islands. Field data on vascular macrophytes were collected from the online national databases of the “Conservation of the island wetlands of the Mediterranean Basin” (MedIsWet). A comprehensive inventory of wetlands was conducted, and information on the main anthropogenic impacts and conservation priorities was compiled. In addition to all vascular hygro- and hydrophytes, we retained information on those species typically adapted to environments with intermittent or temporary wetness. A significant knowledge gap regarding the distribution and conservation of plant species in Mediterranean wetlands was found. A lower endemism rate was observed particularly in coastal wetlands. However, approximately 25% of species, mainly with relatively wide distribution, were identified as endangered or with unknown conservation status. Including all macrophytes adapted to seasonal wetness is crucial when considering wetland conservation efforts. The research emphasised the importance of considering diverse wetland types, including seasonal and permanent, natural and artificial, for effective plant conservation. Artificial wetlands emerged as potential habitats with considerable biodiversity conservation value. This study provides a comprehensive inventory of wetlands and valuable insights into the distribution, ecology, and conservation relevance of aquatic macrophytes in Mediterranean islands. The research enhances our understanding of biogeographic patterns and processes, offers critical information for the management and conservation of Mediterranean island wetlands, and presents a replicable approach that can be applied to other wetland contexts.

Great Salt Lake wetland vegetation and what it tells us about environmental gradients, drought, and disturbance

Great Salt Lake (GSL) wetlands support more than 300 species of migratory birds and provide many ecosystem functions, including flood and drought attenuation, dust mitigation, and water quality improvement. Wetland vegetation is a key factor in providing those services and can also tell us about how healthy a wetland is. From 2103 to 2022, 135 GSL wetlands were surveyed to develop a multi-metric index of GSL wetland condition. That wetland condition data, along with environmental variables like soil and water chemistry and physical disturbance, are summarized here as 1) an ecological characterization of the three main types of GSL wetlands, 2) a description of how the plant community differs across environmental and anthropogenic disturbance gradients, and 3) assessment of the major risks to GSL wetland health. GSL wetland plant species are generally resistant to environmental disturbance because of the anatomical and physical adaptations that allow them to survive in dynamic wetland environments. However, land use conversion and the rapid expansion of invasive species, the major threats to GSL wetland health, have seriously degraded wetland condition around GSL. In addition to being useful in wetland monitoring and assessment, the results presented here can also identify wetlands in need of enhanced protection or those with restoration potential as well as setting realistic wetland restoration goals for the region.

Using UAV multispectral photography to discriminate plant species in a seep wetland of the Fynbos Biome

Wetlands harbour a wide range of vital ecosystems. Hence, mapping wetlands is essential to conserving the ecosystems that depend on them. However, the physical nature of wetlands makes fieldwork difficult and potentially erroneous. This study used multispectral UAV aerial photography to map ten wetland plant species in the Fynbos Biome in the Steenbras Nature Reserve. We developed a methodology that used K-Nearest Neighbour (KNN), Support Vector Machine (SVM), and Random Forest (RF) machine learning algorithms to classify ten wetland plant species using the preselected bands and spectral indices. The study identified Normalized green red difference index (NGRDI), Red Green (RG) index, Green, Log Red Edge (LogRE), Normalized Difference Red-Edge (NDRE), Chlorophyll Index Red-Edge (CIRE), Green Ratio Vegetation Index (GRVI), Normalized Difference Water Index (NDWI), Green Normalized Difference Vegetation Index (GNDVI) and Red as pertinent bands and indices for classifying wetland plant species in the Proteaceae, Iridaceae, Restionaceae, Ericaceae, Asteraceae and Cyperaceae families. The classification had an overall accuracy of 87.4% and kappa accuracy of 0.85. Thus, the findings are pertinent to understanding the spectral characteristics of these endemic species. The study demonstrates the potential for UAV-based remote sensing of these endemic species.

The influence of management practices on plant diversity: a comparative study of three urban wetlands in an expanding city in eastern China.

Rapid urbanization has drawn some aquatic environments into the urban texture from the outskirts of cities, and the composition and distribution of plant species in urban wetlands along the urban gradient have changed. Understanding the drivers of these changes will help in the conservation and utilization of urban wetlands. This study investigated the differences in plant diversity and associated influencing factors in three wetlands, Xixi wetland, Tongjian Lake wetland, and Qingshan Lake wetland, which are located in a core area, fringe area, and suburban area of Hangzhou City, respectively. The results showed that a total of 104 families, 254 genera, and 336 species of plants were recorded in the Xixi wetland; 179 species, 150 genera, and 74 families were found in the Qingshan Lake wetland; and 112 species, 96 genera, and 57 families were collected in the Tongjian Lake wetland. The main plant species and flora distribution of the three urban wetlands showed similarities. Indigenous spontaneous vegetation was highest in the Xixi wetland, while cultivated plant species were most abundant in the Tongjian Lake wetland. The introduction of cultivated plants decreased the distance attenuation effect of plant communities, which led to a certain degree of plant diversity convergence among the three wetlands. Eight endangered plants were preserved in the Xixi wetland by planting them in suitable habitats. Ellenberg's indicator values showed that the proportion of heliophilous plants was higher in the Qingshan Lake wetland, while the proportion of thermophilous plants and nitrogen-loving plants in the Tongjian Lake wetland was higher than in the other two wetlands. The importance of artificial interference factors affecting the differences in plant diversity was significantly higher than that of natural environmental factors in urban wetlands. The preservation of spontaneous plants and the introduction of cultivated plants had an importance of 25.73% and 25.38%, respectively. These were the main factors influencing the plant diversity of urban wetlands. The management mode that did not interfere with spontaneous vegetation and confined maintenance to cultivated plants in the Xixi wetland was beneficial for improving wetland plant diversity. Scientific plant reintroduction can also improve wetland plant diversity.

An overview of the current state of the beaver’s environmental activity

A review of scientific publications devoted to the study of the impact of beaver foraging and construction activities on the plant communities of small rivers in different natural zones has been conducted. Based on the analysis of publications devoted to the study of the beaver's environmental activity, its key role in the successional processes of phytocenoses of riverine biotopes in all natural zones within the native and acquired range is noted. The stages of succession transformations initiated by the beaver's vital activity are considered. The degree of succession transformations depends, first of all, on the density of populations and their stages of maturity. The successions are highly intensive, multidirectional and do not reach the final stage, but are concentrated in the floodplains of small rivers and streams, in the coastal strip of other reservoirs. The vital activity of beavers determines the floristic, faunal, and ecologicaltopological diversity of coastal biogeocenoses. An increase in the proportion of groups of aquatic and wetland plant species was noted, and an increase in biological diversity was revealed in the beaver pond backup zone, regardless of zonal factors. However, being strongly transformed, the coastal vegetation remains zonally conditioned, does not become azonal.

FLORISTIC DIVERSITY OF AQUATIC PLANTS FROM THE INDUSTRIAL BELTS OF THE JAJPUR DISTRICT OF ODISHA, INDIA

A comprehensive study was undertaken to assess the aquatic flora in the Jajpur district of Odisha. The survey was conducted within different water habitats within the industrial belts of Jajpur district from 2021 to 2023, aimed at documenting the diverse aquatic habitats in this region. Extensive and intensive studies were carried out to identify and catalog the aquatic plants, with voucher specimens collected and herbaria prepared using established protocols. The research revealed a total of 84 species of aquatic and wetland plants belonging to 55 genera and 31 families. These included 44 marsh species, 18 amphibious species, 3 submerged species, as well as 10 free-floating and 9 fixed-floating species. These plants not only meet the essential needs of the local community but also play a crucial role in maintaining the ecological balance of the area. Further research will be vital in preserving these valuable bio-resources for future generations.

Removal of PFAS from water by aquatic plants

We have found that aquatic plants can reduce the content of perfluorinated alkyl substances (PFAS) within a short period of time. The aim of this study was to determine the variation in the uptake of PFAS from contaminated water by various wetland plant species, investigate the effect of biomass on PFAS removal, and determine whether laccases and peroxidases are involved in the removal and degradation of PFAS. Seventeen emergent and one submerged wetland plant species were screened for PFAS uptake from highly contaminated lake water. The screening showed that Eriophorum angustifolium, Carex rostrata, and Elodea canadensis accumulated the highest levels of all PFAS. These species were thereafter used to investigate the effect of biomass on PFAS removal from water and for the enzyme studies. The results showed that the greater the biomass per volume, the greater the PFAS removal effect. The plant-based removal of PFAS from water is mainly due to plant absorption, although degradation also occurs. In the beginning, most of the PFAS accumulated in the roots; over time, more was translocated to the shoots, resulting in a higher concentration in the shoots than in the roots. Most PFAS degradation occurred in the water; the metabolites were thereafter taken up by the plants and were accumulated in the roots and shoots. Both peroxidases and laccases were able to degrade PFAS. We conclude that wetland plants can be used for the purification of PFAS-contaminated water. For effective purification, a high biomass per volume of water is required.

Assessment of coal mining impact on the geoecological transformation of the Emerald network ecosystem

Purpose. Geoecological assessment of impact on the ecosystem transformation of a part of Emerald Network object “Samarskyi Lis – UA0000212” caused by coal mining at the section of “Ternivska” mine (Dnipropetrovsk region, Ukraine) using the methods of remote sensing of the Earth in conditions of limited access to the study object due to the state of martial law in Ukraine. Methodology. A complex of standardized field, paper, laboratory and statistical research methods was used. When studying aquatic vegetation, generally accepted methods for describing the species and coenotic composition of vegetation and hydrobotanical mapping were used. The study on soil vegetation was carried out with the selection and description of the main phytocenoses, features of their composition and distribution on the territory. Floristic studies were carried out according to the method for collecting herbarium material. Field routes were carried out on the land surface along the mining of the coal bed with the recording of destructive changes in the landscape (falls, top-soil breaks, sufosis manifestations, cracks, lowering of the relief) and plant groups – the colour and condition of tree, shrub and grass vegetation. In order to compare visual observation data and obtain representative and reliable research results, the facility was monitored additionally using modern geoinformation systems. A satellite observation tool was used; it allowed searching, processing, and obtaining information from satellite data according to various indexes: WRI, NDWI, MNDWI, NDSI. Findings. Negative consequences of the impact of the coal mine “Ternivska” on the geological and ecological transformation of the Emerald network ecosystem “Samarskyi Lis – UA0000212” have been established. It has been proven that long-term underflooding and flooding of lands leads to a change in the species composition of the forest stand, the death of the understory and grass layer, and the complete destruction of the existing plant and animal communities. In flooded areas of oak forests and pine plantations, forest species die out and wetland plant species spread. Over three years (2020–2023), the area of visible and established flooding according to remote sensing data has increased from 1 to 6 hectares, respectively. Originality. Dynamics of the process of the land surface subsidence and protected area flooding has been established according to the data of open-source geoinformation systems and the comparison of various satellite data indexes (WRI, NDWI, MNDWI, NDSI). Gradual changes in the species composition of the forest stand, the death of the understory and the grass layer were revealed. It has been confirmed that long-term flooding leads to the complete destruction of existing plant and animal communities, the destruction of compound complexes of soil mesofauna makes development impossible for the terrestrial invertebrate species that lived in these biotopes before their destruction, including species from the Red List of Ukraine and protected by the Berne Convention. Practical value. In the conditions of limited access for conducting direct geodetic and engineering-geological studies, the methodology of using modern GIS by combining various spectral channels (indexes) is substantiated to determine and study the dynamics of the underflooding (flooding) process in the territory. In combination with traditional field geobotanical research, the results of monitoring observations of the coal mining activity and its impact on the geoecological transformation of the ecosystem of the Emerald Network object are presented for the first time in the region. The negative impact of mining activity on natural conservation areas, which leads to the death and gradual change in the species composition of plants, has been determined.

Unveiling the nitrogen and phosphorus removal potential: Comparative analysis of three coastal wetland plant species in lab-scale constructed wetlands

It is well accepted that tidal wetland vegetation performs a significant amount of water filtration for wetlands. However, there is currently little information on how various wetland plants remove nitrogen (N) and phosphorus (P) and how they differ in their denitrification processes. This study compared and investigated the denitrification and phosphorus removal effects of three typical wetland plants in the Yangtze River estuary wetland (Phragmites australis, Spartina alterniflora, and Scirpus mariqueter), as well as their relevant mechanisms, using an experimental laboratory-scale horizontal subsurface flow constructed wetland (CW). The results showed that all treatment groups with plants significantly reduced N pollutants as compared to the control group without plants. In comparison to S. mariqueter (77.2–83.2%), S. alterniflora and P. australis had a similar total nitrogen (TN)removal effectiveness of nearly 95%. With a removal effectiveness of over 99% for ammonium nitrogen (NH4+-N), P. australis outperformed S. alterniflora (95.6–96.8%) and S. mariqueter (94.6–96.5%). The removal of nitrite nitrogen (NO2−-N)and nitrate nitrogen (NO3−-N)from wastewater was significantly enhanced by S. alterniflora compared to the other treatment groups. Across all treatment groups, the removal rate of PO43--P was greater than 95%. P. australis and S. alterniflora considerably enriched more 15N than S. mariqueter, according to the results of the 15N isotope labeling experiment. While the rhizosphere and bulk sediments of S. alterniflora were enriched with more simultaneous desulfurization-denitrification bacterial genera (such as Paracoccus, Sulfurovum, and Sulfurimonas), which have denitrification functions, the rhizosphere and bulk sediments of P. australis were enriched with more ammonia-oxidizing archaea and ammonia-oxidizing bacteria. As a result, compared to the other plants, P. australis and S. alterniflora demonstrate substantially more significant ability to remove NH4+-N and NO2−-N/NO3−-N from simulated domestic wastewater.

Leaf trait relationships with species ecological optimum and sustainability across wetland plants

Structural and functional parameters of leaves were studied in 19 dominant and abundant species growing in shallows and wet riversides at the mouth of the Maksimikha River (Barguzinsky district, Republic of Buryatia). To evaluate the species ecological optimum Tsyganov’ scales were used (Tsyganov, 1983). To assess the resistance, the potential ecological valence of the species on the illumination scale, as well as the climatic and soil tolerance indices of the species were applied (Zhukova et al., 2010). It was shown that the index of climatic tolerance of the species was negatively correlated with the leaf mass per area (LMA) (r = -0,68) and positively with the chlorophyll photosynthetic activity of (r = 0,51). A tendency was revealed to decrease in LMA and leaf dry matter content (LDMC) and increase in the chlorophyll photosynthetic activity in more thermophilic wetland plants. Leaf area positively correlated with the scores of the species optimum on the soil moisture and acidity scales (r = 0,59 and r = 0,72, respectively). LMA, the content and photosynthetic activity of chlorophyll correlated with the optimum scores on the soil nitrogen supply scale (r = -0,53, r = -0,50 and r = 0,72, respectively). The tolerance index of the species to soil factors was associated only with the content of chlorophylls (r = 0,68) and carotenoids (r = 0,55) per unit leaf area. The potential ecological valence of the species to illumination was positively correlated with leaf density and LDMC (r = 0,58 and r = 0,57, respectively). It was concluded that the thermoclimatic optimum of species of wetland plants, as well as their climate sustainability, are associated with changes in the LMA and chlorophyll photosynthetic activity. Edaphic factors had a greater influence on the structural and functional parameters of leaves than climatic ones, which manifested in a large number of relationships between soil scales and leaf traits. Wetland plant tolerance to a wider range of edaphic conditions was associated with a high content of chlorophylls and carotenoids.

Comparison of vegetation composition in an ephemeral stream channel and the perimeter of pools in subtropical subhumid Central Texas

AbstractEphemeral streams are common in sub‐humid central Texas, but have received little attention. Within ephemeral streams are isolated pools that contain water for longer periods than the channel. This study examined the vegetation composition in an ephemeral dry stream channel and pools in Leon Creek. Twelve sites within the dry channel and twelve ephemeral pools in Leon Creek were surveyed for vegetation between late March and mid‐May 2020 in central Texas, USA. Plant species were similar between the dry channel and pools over a 1.5 km distance indicating that habitats are similar in both allowing the occurrence of upland, facultative, and wetland plant species. A total of 114 species of multiple functional groups were documented in this study. Panicum virgatum had greater coverage at >20% in both the ephemeral channel and pools compared to all other plant species. Ten plant species were dominant with a mean coverage of >3% and no difference was observed for dominant species in the dry channel and pools. The coverage of perennial species were significantly greater in the dry channel and pools but annual coverage in the dry channel was similar to perennial coverage in the pools. Graminoids and forbs were significantly greater in coverage compared to trees, shrubs, vines, and ferns in both the dry channel and pools. Shrub and tree cover was rare accounting for <0.3% coverage. Native species coverage was significantly greater compared to non‐native species in the dry channel and pools. Droughts, flash floods, and scouring events appear to promote perennial graminoids and forbs dominance in Leon Creek with shrubs and trees being uncommon. The results of this study is the first to evaluate vegetation in an ephemeral channel and pools in central Texas and provides current vegetation composition providing information that can be used to compare changes to vegetation in the future.

Relationship among Plant Functional Groups, Soil, and Moisture as Basis for Wetland Conservation

This study characterized the relationship between plant species, soil, and moisture dynamics in the Willamette Valley (Oregon, USA) to obtain a base framework for wetland conservation and restoration. We identified 24 dominant plant species, including the exotic invasive Dipsacus fullonum, distributed throughout the wetland. Plant community analysis indicated that (1) soil moisture during the dry season (August to October) and (2) soil bulk density were the major abiotic drivers of plant community structure. Water potential measurements confirmed the community analysis. Juncus (rush) species appeared to be more tolerant to drought than other typical wetland species. Therefore, dryer conditions due to climate change or water diversion may favor rushes’ persistence. We also found that the dominance of D. fullonum may also negatively affect the native plant species’ survival, which highlights the need for proper management practices. To prevent further vegetation deterioration in sensitive wetland areas, we recommend avoiding hydric diversions to maintain the water supply, exploring manners of controlling invasive species, and preventing livestock grazing. The results of this study contribute to foundational and practical knowledge concerning the influence of soil conditions and moisture availability on the physiological response and distribution of wetland plant species that is required for conservation and management.