Wetlands In Region Research Articles

The fluid definition of the ‘waters of the United States’: Non‐uniform effects of regulation on US wetland protections

AbstractRecent revisions to the definition of the ‘waters of the United States’ (WOTUS) have considerably altered how wetlands are federally regulated under the Clean Water Act. The two most recent modifications to WOTUS, the Clean Water Rule (CWR) and the Navigable Waters Protection Rule (NWPR), represent two opposing approaches to the federal wetland policy. The impacts of these two rules on the regulation of wetlands have as of yet been poorly characterized at broad spatial scales. Using New York State (NYS) as a case study, we evaluated the jurisdictional statuses of more than 253 000 wetlands under the CWR and the NWPR to assess the landscape‐scale effects of WOTUS re‐definitions. We found that statewide and within each of NYS's hydrologic regions, the NWPR protects fewer wetlands and less total wetland area than the CWR. The efficacy of the two regulations varied considerably in space across NYS, highlighting the need for comprehensive, nationwide assessments of wetland policy outcomes. We also observed that both rules produced non‐uniform patterns in jurisdiction across a range of landscape positions and wetland sizes, preferentially protecting large wetlands close to the stream network. This effect was particularly pronounced under the NWPR, which excludes all geographically isolated wetlands from protection. Our findings in NYS emphasize the existence of unique patterns in protected wetlands across spatial scales, highlighting the value in applying geospatial analyses to evaluate environmental policy.

Macroinvertebrate-Based Biomonitoring of Coastal Wetlands in Mediterranean Chile: Testing Potential Metrics Able to Detect Anthropogenic Impacts

Coastal wetlands are suffering from anthropogenic alterations worldwide. Aquatic monitoring based on macroinvertebrates has been successfully used to assess the ecological condition of many aquatic systems worldwide. Nonetheless, studies are still insufficient for the coastal wetlands of the South Pacific. Here, we present a preliminary attempt to select metrics based on aquatic macroinvertebrates to incorporate into coastal wetlands biomonitoring in the Chilean Mediterranean ecoregion. We sampled 25 sites in ten coastal wetlands during the austral spring of 2019. We used an integrated index that considers both human activities at catchment and at local scales to identify sites less or more disturbed. We tested a total of 70 metrics (either traditional or new metrics) representing different aspects of community structure/composition, functions and tolerance to pollution. Two metrics were finally retained: detritivore abundance (traditional metric) and geometric mean body size (new metric). These metrics were able to detect sites impacted by human activities. Thus, they might be considered as candidate metrics for the biomonitoring of these systems and to develop future indices. Moreover, because of their generality, they might also be applicable to coastal wetlands in other Mediterranean regions, including sites where taxonomic identification is still a challenge.

Seasonal assessment of water quality and water quality index (WQI) variations, in Jiangsu Kunshan Tianfu National Wetland Park, China

ABSTRACT Seasonal variations in surface water quality are essential for assessing temporal variations in wetlands pollution due to natural or anthropogenic inputs from both point and non-point sources. The goal of this study was to use established methodologies to estimate the water quality of the Tianfu National Wetland Park based on physicochemical features; sampling was done from eight monitoring locations throughout the wetland region in the summer of 2019 and winter of 2020. The water quality index (WQI) is calculated using the following parameters: Turbidity (NTU), Nitrate, Chlorophyll, TOC, DOC, COD, BOD, Chroma, Ammonium nitrogen, pH, Electric Conductivity, and Total Phosphorus. One-way ANOVA and Tukey’s pairwise comparisons with a 5% significance level were used to compare water quality parameters among the monitoring point’s data. T-test analysis was used to compare the parameters between summer 2019 and winter 2020 and the difference between the water inlet and the water outlet. Cluster analysis was done on the WQI results using Ward’s linkage approach. The analyses of variance (ANOVA) of data revealed statistically significant differences between points of sampling (p < 0.05). The paired t-test revealed significant differences in parameters between summer 2019 and winter 2020; however, all parameters in summer show higher values in the water inlet than water outlet. In winter, TOC, DOC, COD, BOD, Chroma, pH, and Electric Conductivity showed higher values than Turbidity (NTU), Nitrate, Chlorophyll, Ammonium Nitrogen, and Total Pospurus. In general, summer showed higher pollution than winter, and water inlets were more polluted than water outlets indicating that other factors may affect the water quality, such as vegetation cover, temperature, water level, and activities in the wetland during the seasons.

The Long Slog Through the Virtual Swamp: Making a Wetland Podcast in Spanish

The Long Slog Through the Virtual Swamp: Making a Wetland Podcast in Spanish

Importance of Vegetation for Identifying Wetlands in the Lower Mainland Fraser Valley region of British Columbia, Canada using Prevalence Index, Hydrophytic Cover Index, and Dominance Ratio

The Lower Mainland Fraser Valley (LMFV) in British Columbia (BC), Canada is a complex and high stakes environment for wetland identification (Figure 1). High precipitation, subdued topography, and complex site history combine to present formidable challenges to wetland identification and management. Over the last 100+ years, the LMFV has undergone intense and rapid changes. Originally the land was a natural assortment of bogs, swamps and upland forests, which was then cleared for agriculture, and now is undergoing accelerating urban development. Land use competition is intense. Stakes are high: identification of wetlands can make or break development deals. Wetlands are protected in BC by the Water Sustainability Act, and administration is usually through municipal governments and bylaws. Jurisdictional wetlands are identified and mapped as part of a development permitting process.

Heterogeneity of wetland landscapes and their relationships with anthropogenic disturbances and precipitation in a semiarid region of China.

Wetlands in semiarid regions have important ecological functions and provide services that are partly dependent on the landscape pattern and structure; therefore, it is important to assess the heterogeneity of wetland landscape conditions for wetland conservation and management. Widespread wetland degradation resulting from main factors in semiarid regions highlights the need for exploring the heterogeneity of wetland landscapes and their relationships with anthropogenic disturbances and precipitation. Wetlands in our study referred to natural wetlands, including marshes, rivers, and lakes. We used overall landscape metrics to assess wetland landscape conditions and used grid landscape metrics at a scale of 30km using a moving window method to explore the heterogeneity of wetland landscapes during the period (1986-2019) for western Jilin Province. We performed Spearman correlation analyses of the landscape metrics with the Hemeroby index (HI) and mean annual precipitation (MAP). We suggested that wetland landscape composition metrics (e.g., NP and PD) and configuration metrics (e.g., ED and AI) had positive correlations with HI by 2019 (p < 0.01); in addition, wetland landscape composition metrics (e.g., NP and PD) and configuration metrics (e.g., ED) were negatively correlated with MAP during 1986-2019. In conclusion, wetland landscapes have become increasingly fragmented over the past few decades (1986-2019) in western Jilin Province and the reasons for this result mainly include the household contract responsibility system, along with rural productivity, severe overgrazing and reclamation, and climate change. Wetland landscape composition was positively correlated with human interference and negatively correlated with mean annual precipitation.

Hydrogeochemical processes controlling the salinity of surface water and groundwater in an inland saline-alkali wetland in western Jilin, China

Understanding the hydrochemical evolutionary mechanisms of surface water and groundwater in saline-alkali wetlands in arid and semi-arid regions is necessary for assessing how wetland water resource utilization and restoration processes may affect the natural interface between wetland salinity and water. The Momoge National Nature Reserve (MNNR) is an inland wetland in northeastern China that is mainly fed by irrigation water and floods from the Nenjiang River. The purpose of the present study is to describe the spatial distribution characteristics of surface water and groundwater hydrochemistry and salinity in the MNNR and analyze the main processes controlling these parameters. The composition of stable isotopes (δ2H and δ18O) and water chemistry, including the levels of Na, K, Ca, Mg, HCO3, SO4, and Cl, of 156 water samples were analyzed. The results show that the lake water in the MNNR is at a risk of salinization owing to a high degree of evaporation. The analysis of the ion ratio and mineral saturation index showed that the ions in water are primarily derived from aquifer leaching, and the precipitation of Ca2+ and Mg2+ resulted in lower Ca2+ and Mg2+ levels in lake water than in groundwater. Hydrogen and oxygen stable isotope and deuterium excess analyses show that evaporation is the dominant factor controlling the hydrochemistry and salinity of lake water in the MNNR. Long-term effective monitoring of lake water and groundwater must be developed to provide an early warning for the salinization of lake water and a scientific basis for the protection and restoration of wetland ecosystem functions within the MNNR.

Multiproxy paleolimnological records provide evidence for a shift to a new ecosystem state in the Northern Great Plains, USA

AbstractWetlands in the Prairie Pothole Region of the North American Northern Great Plains perform multiple ecosystem services and are biodiversity hotspots. However, climatological changes can result in sudden shifts in these important ecosystems. For example, marked increases in precipitation in the last few decades have resulted in a widespread shift in wetlands across the Prairie Pothole Region to a new ecohydrological state. We used multiproxy analyses (diatom community composition and invertebrate stable isotopes) of 210Pb‐dated sediment cores from two adjacent, but morphologically and hydrologically different, prairie‐pothole wetlands to assess the effects of hydroclimatic variability on these wetland ecosystems. Our results provide evidence that the recent ecohydrological shift in the region's wetlands is unprecedented over the past ca. 178 yr. Oxygen stable isotopes in chironomid head capsules provide a record of paleohydrology changes. The most recent sediments (i.e., those deposited after the state shift) from both wetlands revealed novel changes in diatom communities that differed greatly from earlier community compositions. In addition, a depleted signal in deuterium and 13C carbon stable isotopes observed in chironomid head capsules and Daphnia ephippia, respectively, after 1993 is likely related to an increase in methane production in these wetlands. Our study highlights the importance of considering basin morphometry including whether a wetland has an overflow point, and multiple biological indicators to study climate‐change influences on freshwater ecosystems. Research using these techniques can lead to an improved understanding of recent ecosystem shifts, an understanding that will be essential for future climate‐change adaptation and mitigation in this ecologically important region.

Remote‐Sensing Derived Trends in Gross Primary Production Explain Increases in the CO2 Seasonal Cycle Amplitude

AbstractAn increase in the seasonal cycle amplitude (SCA) of atmospheric CO2 since the 1960s has been observed in the Northern Hemisphere (NH). However, the underlying dominant drivers are still debated. The peak season CO2 uptake by vegetation is critical in shaping the CO2 seasonality. Using satellite‐upscaled gross primary production (GPP) from FLUXCOM and near‐infrared reflectance of vegetation (NIRV), we demonstrate that peak GPP has increased across the NH over the last two decades. We relate this productivity increase to changes in the CO2 SCA using an atmospheric transport model. The increased photosynthesis has strongly contributed to CO2 SCA trends, but with substantial latitudinal and longitudinal variations. Despite a general increase in the CO2 SCA, there are distinct regional differences. These differences are mainly controlled by regional biosphere carbon fluxes, with the remainder explained by non‐biome factors, including large‐scale atmospheric transport, changes in fossil fuel combustion, biomass burning and oceanic fluxes. Using the global flask and in situ CO2 measurement sites, we find that SCA trends at high latitude are mainly driven by increasingly productive natural ecosystems, whereas mid latitude sites around the Midwest United States are mainly impacted by intensified agriculture and atmospheric transport. Averaging across the 15 long‐term surface sites, forests contribute 26% (7%) to the SCA trends, while crops contribute 17% (24%) and the combined shrubland, grassland and wetland regions contribute 23% (37%) for simulations driven by FLUXCOM (NIRv) ecosystem fluxes. Our findings demonstrate that satellite inferred trends of ecosystem fluxes can capture the observed CO2 SCA trend.

Over the hills and through the farms: Land use and topography influence genetic connectivity of northern leopard frog (Rana pipiens) in the Prairie Pothole Region

ContextAgricultural land-use conversion has fragmented prairie wetland habitats in the Prairie Pothole Region (PPR), an area with one of the most wetland dense regions in the world. This fragmentation can lead to negative consequences for wetland obligate organisms, heightening risk of local extinction and reducing evolutionary potential for populations to adapt to changing environments.ObjectivesThis study models biotic connectivity of prairie-pothole wetlands using landscape genetic analyses of the northern leopard frog (Rana pipiens) to (1) identify population structure and (2) determine landscape factors driving genetic differentiation and possibly leading to population fragmentation.MethodsFrogs from 22 sites in the James River and Lake Oahe river basins in North Dakota were genotyped using Best-RAD sequencing at 2868 bi-allelic single nucleotide polymorphisms (SNPs). Population structure was assessed using STRUCTURE, DAPC, and fineSTRUCTURE. Circuitscape was used to model resistance values for ten landscape variables that could affect habitat connectivity.ResultsSTRUCTURE results suggested a panmictic population, but other more sensitive clustering methods identified six spatially organized clusters. Circuit theory-based landscape resistance analysis suggested land use, including cultivated crop agriculture, and topography were the primary influences on genetic differentiation.ConclusionWhile the R. pipiens populations appear to have high gene flow, we found a difference in the patterns of connectivity between the eastern portion of our study area which was dominated by cultivated crop agriculture, versus the western portion where topographic roughness played a greater role. This information can help identify amphibian dispersal corridors and prioritize lands for conservation or restoration.

The improved entropy weighting model in water quality evaluation based on the compound function.

Entropy weight model (EWM) is widely used in water quality evaluation. In the conventional EWM, the weight is a monotone increasing function of the dispersion degree. However, this weighting principle often neglects the heavily polluted indicators. To solve this problem, an improved EWM is designed, in which the weight of the indicator is a compound function of its dispersion degree and pollution degree. In the clean domain, the weight increases with the dispersion degree, while in the polluted domain, the weight decreases with the dispersion degree. And for the same dispersion degree, the larger the pollution degree is, the higher the weight is, and vice versa. Subsequently, the improved EWM is applied to the water quality evaluation of Wucheng Wetland in Poyang Lake, China. Results are as follows: (i) For TP, CODMn, and NH3-N, their dispersion degrees are 0.001, 0.158, and 0.084; and their pollution degrees are 0.971, 0.277, and 0.281, respectively. (ii) According to the improved EWM, the weights of TP, CODMn, and NH3-N are 0.613, 0.197, and 0.190, respectively. (iii) The comprehensive water quality indices of estuary region, wetland region, and the central lake area are 32.5, 30.9, and 35.6, respectively, all of which belong to a "bad" grade. The water environment of Wucheng Wetland suffered serious damage of phosphorus, and the ecosystem faced a high threat. (iv) Compared with the conventional EWM, the improved EWM highlights the importance of polluted indicators, which makes the comprehensive evaluation results more rigorous and reasonable.

Antibacterial Potential of Bacopa monnieri (L.) Wettst. and Its Bioactive Molecules against Uropathogens-An In Silico Study to Identify Potential Lead Molecule(s) for the Development of New Drugs to Treat Urinary Tract Infections.

Urinary tract infections (UTIs) are becoming more common, requiring extensive protection from antimicrobials. The global expansion of multi-drug resistance uropathogens in the past decade emphasizes the necessity of newer antibiotic treatments and prevention strategies for UTIs. Medicinal plants have wide therapeutic applications in both the prevention and management of many ailments. Bacopa monnieri is a medicinal plant that is found in the warmer and wetlands regions of the world. It has been used in Ayurvedic systems for centuries. The present study aimed to investigate the antibacterial potential of the extract of B. monnieri leaves and its bioactive molecules against UTIs that are caused by Klebsiella pneumoniae and Proteus mirabilis. This in vitro experimental study was conducted by an agar well diffusion method to evaluate the antimicrobial effect of 80% methanol, 96% ethanol, and aqueous extracts of B. monnieri leaves on uropathogens. Then, further screening of their phytochemicals was carried out using standard methods. To validate the bioactive molecules and the microbe interactions, AutoDock Vina software was used for molecular docking with the Klebsiella pneumoniae fosfomycin resistance protein (5WEW) and the Zn-dependent receptor-binding domain of Proteus mirabilis MR/P fimbrial adhesin MrpH (6Y4F). Toxicity prediction and drug likeness were predicted using ProTox-II and Molinspiration, respectively. A molecular dynamics (MD) simulation was carried out to study the protein ligand complexes. The methanolic leaves extract of B. monnieri revealed a 22.3 mm ± 0.6 mm to 25.0 mm ± 0.5 mm inhibition zone, while ethanolic extract seemed to produce 19.3 mm ± 0.8 mm to 23.0 mm ± 0.4 mm inhibition zones against K. pneumoniae with the use of increasing concentrations. In the case of P. mirabilis activity, the methanolic extracts showed a 21.0 mm ± 0.8 mm to 24.0 mm ± 0.6 mm zone of inhibition and the ethanol extract produced a 17.0 mm ± 0.9 mm to 23.0 mm ± 0.7 mm inhibition zone with increasing concentrations. Carbohydrates, flavonoids, saponin, phenolic, and terpenoid were common phytoconstituents identified in B. monnieri extracts. Oroxindin showed the best interactions with the binding energies with 5WEW and 6Y4F, −7.5 kcal/mol and −7.4 kcal/mol, respectively. Oroxindin, a bioactive molecule, followed Lipinski’s rule of five and exhibited stability in the MD simulation. The overall results suggest that Oroxindin from B. monnieri can be a potent inhibitor for the effective killing of K. pneumoniae and P. mirabilis. Additionally, its safety has been established, indicating its potential for future drug discovery and development in the treatment for UTIs.

Can calcium-based constructed wetlands improve fluoride removal performance?

The calcium-based substrate, plants and microorganisms and their interactions in constructed wetlands (CWs) could affect the removal performance and transformation of fluoride (F-). CWs with limestone additive enhanced F- removal during the first 40 days. The results of scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) revealed the presence of Ca2+ precipitate components, and X-ray diffraction (XRD) demonstrated the formation of CaF2, Ca5(PO4)3F, and Ca3(PO4)2 precipitation, which all attributed to the synergetic effects of adsorption and co-precipitation. However, the F- removal efficiency of both CWs were diminishing step by step and reached as high as influent concentration around 50th day. The F- effluent concentration stabilized at 3.81 ± 0.02 mg/L and 3.72 ± 0.03 mg/L in calcium-based group and control group, respectively. The weak F- removal performance in plant-uprooted CWs confirmed that plants promoted the release of adsorbed F- and the dissolution of Ca5(PO4)3F by reducing overall pH value of CWs substrate whether with limestone additive or not. Furthermore, the lower relative abundance of fluoride-tolerant bacteria was observed in plant-uprooted CWs compared with planted CWs. This study had important implications for understanding the F- transformation in calcium-based CWs, and could be referenced by the application, design, and construction of constructed wetlands in fluoride-contaminated regions.

Wetland position in the landscape: Impact on water storage and flood buffering

AbstractOn‐going climatic changes and land‐use changes may impact water storage dynamics within wetlandscapes (defined as the entire hydrological catchments of interconnected wetland systems). These dynamics are closely linked to many wetland ecosystem services including flood buffering, nutrient retention and biodiversity support. Here, we investigate if and how current water storage dynamics can differ between wetlands within the same wetlandscape. Based on continuous monitoring of water levels in multiple wetlands throughout a growing season (spring, summer, autumn) in Vattholma, Sweden, we show that there are two distinct storage behaviours depending on the position of the wetland within the landscape. Headwater wetland regions were active in temporary storage of surplus water from regular summer rains while water levels of downstream wetlands dropped to seasonal low values without responding to individual summer precipitation events. Thereby, the downstream wetlands maintained capacity to buffer extreme floods. We also found that headwater wetlands were associated with complex and patchy inundation, which causes habitat conditions to vary over short time scales both within and among these wetlands, in contrast to the prolonged low‐water state of the downstream wetlands. These differences between headwater‐downstream wetlands imply that the functionality of an entire wetlandscape cannot be assessed by simple extrapolation of data from monitoring stations that typically are located downstream of headwater regions. Increased understanding of these differences can support wetland management practices that target location‐specific nature‐based solutions and ecosystem services.

Bat community structure in the Tabasco Plain wetlands

Objective: To describe the diversity of bat communities in two types of wetlands in the coastal region of the Tabasco Plain. Methodology: Sampling was carried out at two different times of the year (dry and wet seasons) for three consecutive years, considering two types of vegetation (mangrove and popal-tular). The samples were collected during 3 effective days (6 h periods with 30 min monitoring intervals) per station, using mist nets. Results: A total of 510 individuals belonging to 22 species of six families were recorded; the phyllostomid bats were the most diverse and abundant. The Artibeus jamaicensis, Noctilio leporinus, and Glossophaga soricina species were the most representative. The vegetation with the greatest diversity was the mangrove with 18 species, while 12 species were found in the popal-tular areas. The diversity of order 1 indicates that the mangrove has 0.78 more diversity than the popal-tular. Seven food guilds were present, including the dominant frugivorous animals. Only three species fall within a protection category, according to NOM-059-SEMARNAT-2010; they comprise 12% of the protected species in the state of Tabasco, Mexico. Implications: In order to determine their diversity and abundance —and ultimately to develop base information—, communities in the wetlands must be evaluated. Conclusions: The mangroves host the greatest diversity and abundance of bats to which they provide shelter and food. Therefore, they are considered crucial for their conservation and, overall, they are important habitats for this group

Remotely sensed data for estimating chlorophyll-a concentration in wetlands located in the Limpopo Transboundary River Basin, South Africa

Wetlands in semi-arid regions are highly productive and biologically diverse ecosystems that contribute significantly to livelihood and economic development and play a substantial role in sustaining rural livelihoods. These ecosystems are not only rich in biodiversity, but also predominantly valuable in terms of the services they provide to people, including water security, hydrological regulation, and other services. Chlorophyll-a concentrations and associated dynamics in two tropical wetland systems were estimated in the Makuleke and Nylsvlei wetlands. The Makuleke and Nylsvlei wetlands are in the Limpopo Transboundary River Basin, South Africa. Moderate-resolution Landsat 8 images for September 2018 and June 2019 and in situ field measurements were used to estimate and map chlorophyll-a concentration from the two wetlands. Landsat-derived chlorophyll-a concentrations were validated using field-derived chlorophyll-a measurements. Validation was implemented to assess the consistency of the remotely sensed chlorophyll-a estimates. The relationship between field-measured chlorophyll estimates and Landsat-derived chlorophyll estimates was determined using the coefficient of determination (r-square: R2) and the root mean square error (RMSE). The results showed that the Makuleke wetland had low estimates of Chl-a during September 2018. The variation of Chl-a concentration in Makuleke ranged from 0 to 1.15 μg/L, whereas for Nylsvlei the wetland range varied between 0 and 1.42 μg/L, for the period under study. The spatial characterization of Chl-a concentration varied significantly between the two wetlands, with much of it concentrated along the wetland shorelines. The finding of this study underscores the relevance of remotely detected data in the evaluation and routine monitoring of wetland water quality, a previously challenging task within situ measurements.

Inundation prediction in tropical wetlands from JULES-CaMa-Flood global land surface simulations

Abstract. Wetlands play a key role in hydrological and biogeochemical cycles and provide multiple ecosystem services to society. However, reliable data on the extent of global inundated areas and the magnitude of their contribution to local hydrological dynamics remain surprisingly uncertain. Global hydrological models and land surface models (LSMs) include only the most major inundation sources and mechanisms; therefore, quantifying the uncertainties in available data sources remains a challenge. We address these problems by taking a leading global data product on inundation extents (Global Inundation Extent from Multi-Satellites, GIEMS) and matching against predictions from a global hydrodynamic model (Catchment-based Macro-scale Floodplain – CaMa-Flood) driven by runoff data generated by a land surface model (Joint UK Land and Environment Simulator, JULES). The ability of the model to reproduce patterns and dynamics shown by the observational product is assessed in a number of case studies across the tropics, which show that it performs well in large wetland regions, with a good match between corresponding seasonal cycles. At a finer spatial scale, we found that water inputs (e.g. groundwater inflow to wetland) became underestimated in comparison to water outputs (e.g. infiltration and evaporation from wetland) in some wetlands (e.g. Sudd, Tonlé Sap), and the opposite occurred in others (e.g. Okavango) in our model predictions. We also found evidence for an underestimation of low levels of inundation in our satellite-based inundation data (approx. 10 % of total inundation may not be recorded). Additionally, some wetlands display a clear spatial displacement between observed and simulated inundation as a result of overestimation or underestimation of overbank flooding upstream. This study provides timely information on inherent biases in inundation prediction and observation that can contribute to our current ability to make critical predictions of inundation events at both regional and global levels.

Effects of Sediment Types on the Distribution and Diversity of Plant Communities in the Poyang Lake Wetlands

At small scales, sedimentary deposition types mediate hydrological changes to drive wetland vegetation distribution patterns and species diversity. To examine the effects of sediment types on the distribution and diversity of plant communities in a wetland region, 150 quadrats were investigated (elevation range of 10.5–12.5 m) in the lake basin areas of Poyang Lake. We divided the surface soil into three sediment types (lacustrine sediments, fluvio-lacustrine sediments, and fluvial sediments), and then compared and analyzed the distribution and species diversity of the wetland plants among them. The results revealed the following findings: (i) within this elevation range, Carex cinerascens, Carex cinerascens–Polygonum criopolitanum, Polygonum criopolitanum, and Phalaris arundinacea communities exist; (ii) from lacustrine sediments to fluvial sediments, the distribution of plant communities showed a transition trend—with the Carex cinerascens and Phalaris arundinacea communities shifting into the Polygonum criopolitanum community; (iii) detrended correspondence analysis and redundancy analysis demonstrated that the soil particle composition and flood duration in 2017 generated a differential wetland plant distribution under the conditions of three sediment types along the littoral zones of Poyang Lake; and (iv) the plant communities on the lacustrine sediments had a higher species diversity than those established on the fluvio-lacustrine sediments and fluvial sediments.

Temporal and Spatial Variation of Wetland CH4 Emissions from the Qinghai–Tibet Plateau under Future Climate Change Scenarios

Wetlands are an important natural source of methane (CH4), so it is important to quantify how their emissions may vary under future climate change conditions. The Qinghai–Tibet Plateau contains more than a third of China’s wetlands. Here, we simulated temporal and spatial variation in CH4 emissions from natural wetlands on the Qinghai–Tibet Plateau from 2008 to 2100 under Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5. Based on the simulation results of the TRIPLEX-GHG model forced with data from 24 CMIP5 models of global climate, we predict that, assuming no change in wetland distribution on the Plateau, CH4 emissions from natural wetlands will increase by 35%, 98% and 267%, respectively, under RCP 2.6, 4.5 and 8.5. The predicted increase in atmospheric CO2 concentration will contribute 10–28% to the increased CH4 emissions from wetlands on the Plateau by 2100. Emissions are predicted to be majorly in the range of 0 to 30.5 g C m−2·a−1 across the Plateau and higher from wetlands in the southern region of the Plateau than from wetlands in central or northern regions. Under RCP8.5, the methane emissions of natural wetlands on the Qinghai–Tibet Plateau increased much more significantly than that under RCP2.6 and RCP4.5.

Seasonal inundation dynamics and water balance of the Mara Wetland, Tanzania based on multi-temporal Sentinel-2 image classification

Anthropogenic hydrologic alternations are a threat to flood dependent wetland ecosystems like The Mara Wetland in Tanzania, which plays an important role in regulating the quality, timing and magnitude of the flow of water into Lake Victoria and provides natural resources and habitat for a variety of species. Baseline information on the spatiotemporal dynamics of the seasonal inundation is critical to manage potential threats such as dam construction and local climate change, but is challenging to acquire due to the heterogeneity of the landscape caused by the interspersion of open water and emergent vegetation. In this study, intra- and inter-annual inundation pattern of the Mara Wetland are reproduced for 2017–2019 using remotely sensed data. A Random Forest (RF) algorithm is trained bi-seasonally, using eight Sentinel-2 bands, five water- and vegetation-indices and a Digital Surface Model (DSM) to classify the land cover of the wetland region in a semi-automated way, by processing a total of 73 Sentinel-2 scenes based on wet- and dry-state training images for 2017. The scenes are classified into seven classes; three wetland- and four dryland-classes. The overall classification accuracy achieved (based on an independent validation set) is 98.6%. The inundation extents are used in combination with available hydrological field-data to estimate the water balance. The seasonal expansion and contraction of the wetland follows a consistent bi-modal regime, and the results from the water balance affirm the importance of river-flow during the dry-season and local precipitation for the seasonal fluctuations in water-availability.