Wetland Research Articles

“Liquid assets”: Coastal wetlands, regional parks, and the protection of Mediterranean deltas

After a century of accelerating drainage, in the 1960s coastal wetlands became the object of unprecedented protection campaigns around the world. This paper compares the history of three successful cases of coastal wetland protection in the Mediterranean between the 1960s and 1980s: the Rhône (France), Po (Italy), and Ebro (Spain) River deltas. As most of the coast of Mediterranean Europe, these three cases were at the center of renewed redevelopment attempts, to further expand intensive agriculture, industry, and seaside tourism, which invariably involved wetlands drainage. In these three cases, protection was achieved by establishing “regional parks” in the deltas. We argue that it was not by chance. Wetland advocates at the international, national, and local scales coated their plea for protection in the language of economics, making the case for wetlands’ value as “liquid assets.” They argued that wetland protection could rhyme with development and, abandoning initial projects to protect deltas as national parks, focused their efforts on creating regional parks instead. Stemming from the European regional planning movement, the regional park framework proved expedient to combine development expectations and wetland protection. Thanks to modular land use zoning, it promised to combine productive activities with protected areas, without imposing uniform restrictions on the entire deltas such as those often associated with national parks. The history of these three coastal parks, therefore, sheds light on the counterintuitive but strong relationship existing between coastal development and protection by uncovering the discursive strategies and unlikely coalitions that made conservation possible.

Are Water Use Efficiency and Effectiveness Relatively Lower in Arid Zones? Comparative Analyses of the Water Productivity of Typical Crops

Agriculture is the largest water user of all sectors. In arid regions in particular, achieving efficient water use in agriculture is an important way to solve water scarcity. However, the difference in water use efficiency between arid and humid regions has long been a focus of academic debate. Many studies consider water use efficiency to be higher in humid areas due to the abundance of water resources. This view is based on the fact that less irrigation in humid areas may lead to higher crop yields and better conditions for agricultural production; however, it ignores the efforts of researchers and agricultural workers in arid zones who have attempted to develop efficient water-saving technologies, as well as the effect of natural conditions on agricultural production. Correctly evaluating the efficiency of agricultural water use in arid zones is important for achieving efficient use of water resources, as well as for water management decisions. This study calculates the yield structure and water productivity of typical crops in both arid and humid regions in China based on the footprint theory and other methodologies. This approach allows for an accurate assessment of irrigation water benefits in various regions, providing a scientific basis for improving agricultural water use efficiency under different climatic conditions. The study results indicate that the average reliance on blue water for wheat and cotton gradually increases from 49.9% to 93.6% as regional aridity intensifies, ranging from the Central China Humid Region to the Northwest China Arid Region. Similarly, the average contribution of blue water to crop yield rises from 31.0% to 100%, while irrigation water productivity increases from 0.27 kg·m−3 to 0.53 kg·m−3. Finally, this study concludes that, in arid zones with lower precipitation and more hours of sunshine, a higher dependence on blue water for crop growth and development leads to a higher productivity of irrigation water. In addition, in arid zones, the focus should be on optimizing the use of irrigation water and improving irrigation technology and efficiency, while, in humid zones, there should be more use of natural precipitation to efficiently reduce dependence on irrigation water.

The role of building mass configuration and material selection for mitigating the intensity of the urban heat island

The knowledge of urban heat island (UHI) mitigation for the materials and geometry of urban areas requires enrichment. This study compares to the thermal conditions on two different building mass configurations (Superblock and horizontal residential areas), that involve geometry aspect (density, orientation) and materials aspect (softscape, pavement, roof, wall). A surface urban heat island (SUHI) survey was conducted using Landsat thermal imagery, followed by ground surveys in selected areas. Data collected in both areas included air temperature, relative humidity, air velocity, and globe temperature area. The results show that the superblock configuration had a low SUHI intensity due to the proportional orientation of East-West-North-South (0.56–0.44) and large shading (average of 0.31 m2). In contrast, in the dense residential areas, the intensity of SUHI was high because the proportion of East-West walls was wider than North-South (0.8–0.2), and the shading was low (average of 0.15–0.16 m2). Façade and ground heating occurred owing to the use of heavy-weight materials, which was indicated in the thermal imagery, with a solar heating index in a vertical cluster mass configuration of 21.7 and a horizontal grid of 55.9. Convective cooling occurred in a vertical geometry because the buildings generated turbulence that removed warm air, whereas it did not occur in a horizontal geometry. The convective cooling index for the vertical cluster mass configuration was 0.62, whereas that for the horizontal grid configuration was 0.09. This indicates that regional planning must incorporate geometric and material considerations to control the urban thermal environments.

Blue carbon storage of tidal flats and salt marshes: A comparative assessment in two Chinese coastal areas

Coastal wetlands are blue carbon (C) reservoirs and play an important role in mitigating climate change by efficiently capturing and storing organic carbon (OC). However, assessments of blue C sequestration focus primarily on soil organic carbon (SOC) inventories of vegetated coastal ecosystems and often neglect the potential of tidal flats to sequestrate C. To address the issue, a comparative assessment was carried out for two representative coastal wetlands in China: the Yellow River Delta and Yancheng coastal wetlands. The study focused on distinct types of coastal ecosystems including unvegetated tidal flats and three types of salt marshes vegetated by either Spartina alterniflora, Suaeda salsa, or Phragmites australis. We combined field sampling and data synthesis to assess the OC stock of different coastal areas and evaluate the regional OC storage. The results indicated that vegetated salt marshes exhibited higher OC stocks per unit area compared to unvegetated tidal flats in both regions. Interestingly, tidal flats in the Yellow River Delta displayed comparable OC stocks to S. salsa marsh on the Yancheng coast. The regional OC storage was estimated to be 5.64 ± 0.61 Tg C for the Yellow River Delta and 9.96 ± 1.52 Tg C for the Yancheng coast. Tidal flats with low SOC stock per unit area were the primary contributors to regional OC storage, accounting for over 75 % of the total. This predominance was attributed to the extensive distribution of tidal flats along China's coast, indicating their significant potential as blue C sinks. Overall, this study provides insights into the OC storage potential of various wetland types in China and highlights the importance of considering tidal flats in estimates of blue C sequestration.

The effect of Sesuvium portulacastrum for reducing inorganic nitrogen pollution in coastal mariculture wetland

Mariculture ponds are essential components of the coastal wetland, which are often criticized by eutrophication risk for the dissolved inorganic nitrogen (DIN) input to the coastal zone by the culture tailwater. However, the reduce of this DIN pollution was difficult because the tailwater is hard to collect and the treatment is inefficient and expensive. Sesuvium Portulacastrum is a coastal vegetation which has high efficiency in DIN absorption from the seawater and sediment. In this study, we use Sesuvium Portulacastrum as a tool species to study the control behavior of the DIN in mariculture ponds wetland. The change trend of DIN in pond water and benthic species in pond sediment was investigated. The results showed that Sesuvium Portulacastrum reduced NH4+, NO3-, and NO2- in the pond water by 83.21%, 95.22%, and 91.32%, respectively. The species number of benthic organisms was enhanced from 2 to 5 and the species structure was more optimized in Sesuvium Portulacastrum pond than control pond. At the end of the experiment, eutrophication indicator species (Capitella capitata) was disappeared in the Sesuvium Portulacastrum pond. Those suggest that the coastal vegetation (Sesuvium Portulacastrum) have great potential to eliminate DIN pollutants in mariculture pond wetland.

Fate of soil organic carbon in estuarine mangroves: Evidences from stable isotopes and lignin biomarkers

Coastal wetlands are increasingly recognized for their role in climate change mitigation, particularly through the sequestration of soil organic carbon (SOC). Despite widespread acknowledgement of their importance, the variation in organic carbon (OC) sources among different estuarine mangrove wetlands, and how these sources interact with environmental factors, is not fully elucidated. This research focuses on the role of estuarine mangrove wetlands in climate change mitigation through SOC sequestration. It explores the distribution, sources, and decomposition of SOC in a wetland with four mangrove communities along a tidal gradient. These include a tidal flat, a Sonneratia apetala forest, a mixed S. apetala and Kandelia obovata forest, and a K. obovata forest. The study employs biogenic element analysis (C, N, lignin phenols) and natural stable carbon isotope ratios (δ13C and δ15N) to assess SOC. Key findings show a decrease in SOC and total nitrogen (TN) from the upstream K. obovata forest to the downstream tidal flat. A stable isotope mixing model reveals a diminishing mangrove-derived OC contribution in topsoil (0–40 cm), estimated at 62 % in the K. obovata forest, 45 % in the central region, and 24 % in tidal flats. Soil profiles suggest microbial decomposition as the main isotope fractionation mechanism, with lignin analysis indicating woody angiosperms as the primary OC source. These findings enhance understanding of OC origins and decomposition in coastal wetlands and inform “blue carbon” management, highlighting the terrestrial-estuary continuum's significance.

Assessing sediment CO2 effluxes in the coastal ecosystem of North Sumatra, Indonesia

Coastal wetlands including mangrove play a vital role in regulating the local and global carbon cycle. Coastal areas contribute greatly to the carbon exchange process due to the complex interactions that occur between the atmosphere, land, and oceans. One of the important components in coastal carbon dynamics is CO2 gas exchange between soil, water and the atmosphere. This study aims to assess CO2 efflux across various land covers (namely natural mangrove, restored mangrove, and converted mangroves to oil palm and aquaculture pond) in the coastal areas of North Sumatra Province, and analyze the effect of sea tides and ebbs on the rate of CO2 efflux and their connection with the number and area of macrozoobenthos burrows. We applied direct sampling by using the static closed chamber method attached to portable CO2 analyzer. The mean of CO2 efflux in natural mangrove forest land covers was 866±585 mgCO2/m2/h during low tide conditions and 1137±792 mgCO2/m2/h during high tide conditions, followed by oil palm plantations at 760.71±341 mgCO2/m2/h, restored mangroves during low tide of 575.24±326 mgCO2/m2/h and 597.11±180 mg CO2/m2/h during high tide conditions, and the lowest was recorded in ponds at 588.55±358 mgCO2/m2/h. Further, we observed that tidal conditions affect the magnitudes of CO2 efflux in natural and restored mangrove forests, and we did not observe similar pattern in oil palms and ponds since these land covers were not influenced by regular tidal input. We also observed that no significant relationship between the number and area of macrozoobenthos burrows and CO2 efflux. Our findings suggest that CO2 effluxes in coastal wetlands are highly dynamic and presumably driven by complex factors and therefore, understanding their magnitudes and drivers requires extensive measurement covering large spatial and temporal scales.

Spatiotemporal Distribution and Habitat Characteristics of Shorebirds in the Coastal Wetlands of Dalian, Liaoning, China

The coast of Dalian in Liaoning Province, China, is one of the most important habitats for migratory shorebirds along the East Asia–Australasian Flyway. However, the coastal areas of Dalian have been modified extensively by various projects, including reclamation and the construction of aquaculture and port facilities, embankment buildings, cross-sea passages, and wind farms, which have led to significant damage to the coastal habitats of shorebirds. Assessing the spatiotemporal distribution and habitat characteristics of shorebirds is of great importance to biodiversity conservation. The present study involved a 15-month-long survey of shorebirds in nine coastal wetlands of Dalian from August 2021 to October 2022. In total, 31 species of shorebirds, belonging to five families, were recorded. Migratory shorebirds were the most frequently observed, accounting for 77% of the recorded shorebirds. Dunlin (Calidris alpina), Kentish plover (Charadrius alexandrinus), Eurasian curlew (Numenius arquata), and Far Eastern curlew (Numenius madagascariensis) were the most abundant species. Both species richness and species abundance peaked in May and again in September. The Zhuanghe Estuary boasted the highest species diversity, while the Huli Estuary wetland exhibited the greatest species abundance. The type of habitat and the spatial extent of natural wetlands were the main variables influencing the spatial distribution of waterbirds. By identifying the population characteristics and habitat status of shorebirds in Dalian, the results provide support for shorebird conservation and habitat management.

High salinity restrains microplastic transport and increases the risk of pollution in coastal wetlands

Microplastics (MPs) pollution in coastal wetlands has attracted global attention. However, few studies have focused on the effect of soil properties and structure on MP transport in coastal wetlands. Salinity is one of the most pivotal environmental factors and varies in coastal wetlands. Here, we conducted column experiments and employed fluorescent labeling combined with Derjaguin–Landau–Verwey–Overbeek (DLVO) theoretical calculations to reveal the vertical transport behavior of MPs. Specifically, we investigated the influence of five salinity levels (0, 0.035, 0.35, 3.5, and 35 PSU) on MP transport in different coastal wetlands soils and a sand through the X-ray photoelectron spectroscopy and nondestructive computed tomography technique. The results indicated that the migration capability of MPs in soils is significantly lower than in quartz sand, and that the migration capability varies depending on the soil type. This variability may be due to soil minerals and microporous structures providing numerous attachment sites for MPs and may be explained by the DLVO energy barrier of MP-Soil (6568–7767 KT) and MP-sand (5250 KT). Salinity plays a crucial role in modifying the chemical properties of pore water (i.e., zeta potential) as well as altering the soil elemental composition and pore structure. At 0 PSU, the maximum C/C0 of MPs through the sand, Soil 1, and Soil 2 transport columns were 37.86 ± 2.36 %, 23.96 ± 1.71 %, and 3.94 ± 0.68 %, respectively. When salinity increased to 3.5 PSU, MP mobility decreased by over 20 %. Additionally, a salinity of 35 PSU may alter the soil pore distribution, thereby changing water flow paths and velocities to constrain the migration of MPs in soils. These findings could provide valuable insights into understanding the environmental behavior and transport mechanisms of MPs, and lay a solid scientific basis for accurately simulating and predicting the fate of MPs in coastal wetland water–soil systems. We highlight the effect of salinity on the fate of MPs and the corresponding priority management of MPs risks under the background of global climate change.

Leaf Physiological Responses and Early Senescence Are Linked to Reflectance Spectra in Salt-Sensitive Coastal Tree Species

Salt-sensitive trees in coastal wetlands are dying as forests transition to marsh and open water at a rapid pace. Forested wetlands are experiencing repeated saltwater exposure due to the frequency and severity of climatic events, sea-level rise, and human infrastructure expansion. Understanding the diverse responses of trees to saltwater exposure can help identify taxa that may provide early warning signals of salinity stress in forests at broader scales. To isolate the impacts of saltwater exposure on trees, we performed an experiment to investigate the leaf-level physiology of six tree species when exposed to oligohaline and mesohaline treatments. We found that species exposed to 3–6 parts per thousand (ppt) salinity had idiosyncratic responses of plant performance that were species-specific. Saltwater exposure impacted leaf photochemistry and caused early senescence in Acer rubrum, the most salt-sensitive species tested, but did not cause any impacts on plant water use in treatments with <6 ppt. Interestingly, leaf spectral reflectance was correlated with the operating efficiency of photosystem II (PSII) photochemistry in A. rubrum leaves before leaf physiological processes were impacted by salinity treatments. Our results suggest that the timing and frequency of saltwater intrusion events are likely to be more detrimental to wetland tree performance than salinity concentrations.

A comparative analysis of dendrometric, macromorphological, and micromorphological characteristics of Pistacia atlantica subsp. atlantica and Pistacia terebinthus in the middle Atlas region of Morocco.

The genus Pistacia, with its species having notable ecological, economic, and medicinal implications, demonstrates remarkable environmental adaptability. The central objective of the study is to analyze interspecific variations between Pistacia atlantica subsp. atlantica and Pistacia terebinthus across three distinct bioclimatic zones in the Middle Atlas region of Morocco. The methodology includes collecting dendrometric measurements and conducting macromorphological examinations on these two taxa, with a detailed analysis of 27 qualitative and quantitative variables. A micro-morphological analysis of leaves, using scanning electron microscopy (SEM), is employed to explore specific features such as size and stomatal density, as well as qualitative aspects like epidermal cell shape and trichomes. Dendrometric measurements have revealed that the canopy surface and the number of trunks per tree can serve as distinctive features between the two species. Regarding the sex ratio of Pistacia atlantica subsp. atlantica, 59% of the examined trees are males, primarily associated with the jujube tree in arid zones and the dwarf palm in humid areas. In contrast, female Pistacia terebinthus exhibit a similar percentage, predominantly associated with oak groves and cade juniper in their distribution areas. Principal component analysis of biometric measurements emphasized a significant disparity between the two species, representing 60.25% of the total variance. The use of SEM unveiled new features facilitating the identification of the two species. By leveraging the macromorphological and micromorphological variability of pistachio trees, we can qualify those best suited to diverse bioclimates. In this regard, we suggest incorporating them into reforestation and rehabilitation programs aimed at restoring our declining ecosystems.

A comprehensive analysis of new particle formation across the northwest Atlantic: Analysis of ACTIVATE airborne data

New particle formation (NPF) is a critical source of particles and cloud condensation nuclei, yet there are scarce vertically-resolved measurements addressing NPF across different seasons in marine regions. This study leverages a multi-season set of airborne data from the NASA ACTIVATE mission between 2020 and 2022 to examine NPF characteristics over the northwest Atlantic ranging from the polluted U.S. East Coast to as far downwind (>1000 km) as Bermuda. Using the number concentration ratio above 3 and 10 nm (N3:N10) as a NPF indicator, we observe the highest ratios in the coldest months and comparable ratios over Bermuda relative to the U.S. East Coast. Within seasons, the highest and lowest ratios are found immediately above cloud tops and at the lowest possible flight altitudes (∼150 m above sea level), respectively. The ratio of (N3-N10)/N3 ranges from 0.16 to 0.29 depending on altitude, proximity to clouds, and season. The N3:N10 and (N3-N10)/N3 ratios increase with altitude up to as high as 9 km, with a case study showing favorable conditions around relatively thicker and precipitating cloud systems presumably due to high actinic fluxes and reduced aerosol surface area. Regression modeling reveals that increased N3:N10 is influenced most by reductions in temperature, relative humidity, and aerosol surface area. This work emphasizes the importance of both NPF in remote marine regions like Bermuda and vertical heterogeneity that exists in its contribution to aerosol and cloud condensation nuclei number budgets.

Reconstructing the rapid transitions of ecosystems during the mid-late Holocene: A pollen record from Haixing wetland in Bohai Bay, North China

Vegetation in coastal regions is sensitive to climate and sea-level changes. However, currently there is still a lack of understanding about the stability of the Holocene coastal ecosystem and the rapid conversion processes of different coastal wetland ecosystems. In this study, the high-resolution vegetation succession history of the southwest coast of Bohai Bay during the mid-late Holocene was revealed, based on pollen analysis and REVEALS model, and the rate of vegetation change was estimated. Furthermore, the characteristics and mechanisms of different ecosystem changes were explored. The results indicate that there was a prolonged transition from shallow sea to lagoon before the formation of the Haixing wetland during the interval of 7500–4100 cal yr BP. The rate of watershed vegetation change increase significantly under the common influence of the 4.2 ka event and human activities, causing a regime shift in the mountain forest ecosystems and a decrease in landscape resilience. It was characterized by a substantial reduction in broad-leaved forests (from>30% to<5%), especially for Quercus (∼3%), which have not recovered to pre-event levels since the end of the 4.2 ka event. Since 3500 cal yr BP, the Haixing area was completely detached from the influence of the Bohai Sea, forming freshwater wetlands. The local vegetation rapidly shifted from alkali-tolerant communities that followed the sea retreat to freshwater marsh plant communities. During 2000–1100 cal yr BP, under the strong impact of human activities, the succession of forest and grassland communities in the basin became more frequent. The area of coastal salt marshes expanded, with salt-tolerant plant communities taking the absolute advantage. The wetland vegetation landscape became closer to the modern appearance. Overall, our study provides new evidence for understanding the rapid evolution of coastal ecosystems in East Asia influenced by a combination of climate, hydrology and humans. It will help guide the coastal regions in facing the challenges of future global climate changes.

Groundwater driven carbon fluxes in a restored coastal saltmarsh wetland: Implications for coastal wetland restoration

Coastal wetlands play a crucial role in the global carbon cycle, yet they have been extensively degraded over the past decade. Though restoration efforts are underway worldwide, there is limited understanding of the role groundwater plays in transporting dissolved carbon within restored wetlands. Here, we address this knowledge gap by investigating water and carbon fluxes in the restored Tomago Wetlands in coastal NSW, Australia. We aim to 1) quantify surface water exports of the main carbon components, 2) estimate greenhouse gas emissions from the aquatic parts of the wetland, and 3) determine the contribution of groundwater discharge to the surface water carbon export and greenhouse gas emissions from the wetland. Sampling took place following a wet period and a freshening event. A radon mass balance model estimated groundwater discharge contributing 10 % to the surface water flow in the restored wetland. The wetland was a source of four of the five main carbon components including DOC, DIC, alkalinity, and CO2, with most of the exported carbon being in the form of alkalinity. Surface water DOC, DIC, alkalinity, and CO2 exports were, 1.3 ± 0.5, 35.5 ± 13.1, 39.4 ± 14.6 and 6.5 ± 2.1 mmol/m2/d, respectively. The average water to atmosphere flux of CO2 and CH4 were 104 ± 209 (mmol/m2/d) and 21 ± 42 (µmol/m2/d). Groundwater-driven carbon fluxes contributed 100 % of the surface water DOC, 30 % of the DIC, 15 % of the alkalinity exports, and 5 % of the overall CO2 losses (lateral aqueous export + atmospheric emissions) from the wetland, with minor contributions to CH4. Carbon exports from both the wetland and groundwater observed in this restored wetland were found to be lower than those reported in the literature for natural or mature wetlands. This would have important implications when developing carbon accounting methods. Overall, our findings highlight the importance of groundwater in carbon transport within restored wetlands and emphasise the need for inclusion of shallow groundwater dynamics in carbon budgets and inventories of coastal wetlands that have or will undergo restoration.

Evaluation of subsurface soil water content estimate methods: Maximum entropy vs. exponential filter

Profile soil water content (SWC) is a vital variable in the atmosphere-vegetation-soil system. Although remote sensing currently can provide reliable surface SWC data (∼5 cm depth), acquiring accurate subsurface SWC data from existing reanalysis products remain challenging. In this study, we evaluated two widely used methods in estimating subsurface SWC, namely the exponential filter (ExpF) and the principle of maximum entropy (POME). The evaluation is carried out in two distinct areas on the Tibetan Plateau using ground observations collected from two monitoring networks: the Maqu network area characterized by cold humid climate and grassland and the Shiquanhe network area characterized by cold arid climate and bare ground. The results indicate that POME generally performs better than ExpF in both areas, particularly in deeper soil layers. Specifically, the accuracy of estimated SWC using the ExpF method decreases with depth, while it increases with depth using the POME method. Additionally, both methods achieve commendable performance at a depth of 10 cm in both areas. The deficiency of ExpF is mainly reflected in underestimations for dry cases, which is amplified with increasing depth. Dry cases account for 51 % in the humid area and 68 % in the arid area throughout the study period. Consequently, the ExpF method yields higher root mean square differences (RMSD) by 30 % and 113 % in the humid area at depths of 20 and 40 cm, respectively, compared to the POME method. Similarly, it results in higher RMSD values by 220 % and 200 % in the arid area. As expected, the superior performance of POME in deeper soil layers is primarily attributed to the incorporation of additional bottom and profile mean SWC observations. However, it also potentially introduces uncertainties when integrated with satellite-based data, which inherently contains errors compared to ground observations. To assess the potential of these two methods in large-scale applications combined with satellite-based datasets, this study conducted further evaluation of both methods with required input data derived from the soil moisture active and passive mission (SMAP). The results demonstrate that the performance of both methods in estimating subsurface SWC is acceptable in both humid and arid areas, although some bias is transferred from the input data. They achieve average RMSD values of 0.034 and 0.055 m3/m−3(−|−) in the humid area for the ExpF and POME methods, respectively, and 0.021 and 0.014 m3/m−3(−|−) in the arid area.

Texas Water Observatory: A Distributed Network for Monitoring Water, Energy, and Carbon Cycles Under Variable Climate and Land Use on Gulf Coast Plains

Abstract In the Gulf Coastal Plains of Texas, a state-of-the-art distributed network of field observatories, known as the Texas Water Observatory (TWO), is developed to better understand the water, energy, and carbon cycles across the critical zone (encompassing aquifers, soils, plants, and atmosphere) at different spatiotemporal scales. Using more than 300 advanced real-time / near-real-time sensors, this observatory monitors high-frequency water, energy, and carbon storage and fluxes in the Brazos River corridor, which are critical for coupled hydrologic, biogeochemical, and land-atmosphere process understanding in the region. TWO provides a regional resource for better understanding and/or managing agriculture, water resources, ecosystems, biodiversity, disasters, health, energy, and weather/climate. TWO infrastructure spans common land uses in this region, including (traditional/aspirational cultivated agriculture, rangelands, native prairie, bottomland hardwood forest, and coastal wetlands). Sites represent landforms from low-relief erosional uplands to depositional lowlands across climatic and geologic gradients of central Texas. We present the overarching vision of TWO and describe site design, instrumentation specifications, data collection, and quality control protocols. We also provide a comparison of water, energy, and carbon budget across sites, including evapotranspiration, carbon fluxes, radiation budget, weather, profile soil moisture and soil temperature, soil hydraulic properties, hydrogeophysical surveys, groundwater levels and groundwater quality reported at TWO primary sites for 2018-2020 (with certain data gaps). In conjunction with various earth-observing remote sensing and legacy databases, TWO provides a master testbed to evaluate process-driven or data-driven critical zone science, leading to improved natural resource management and decision support at different spatiotemporal scales.

Invasive wild boar affected feral hog skull evolution over 25 years in Brazilian Pantanal wetland

Abstract The morphological plasticity of the Sus scrofa wild–domestic species complex is evident in both free-ranging morphotypes and domestic breeds. The Brazilian Pantanal feral hog (“porco-monteiro”) evolved after a long-term feralization process and represents a significant proportion of the mammalian biomass in the region. Its coexistence with native fauna brings several ecological impacts, which are mitigated by the Brazilian Pantanal wetland vastness and resource availability. They are a local subsistence game resource but also impact crops and pastures. Around the 2000s to mid-2010s, numerous European wild boar were introduced in Brazil to fulfill a demand for gourmet meat. Wild boar was also introduced to the Brazilian Pantanal as a game species and to breed with porco-monteiro feral hogs in a commercial venture to produce an even more exotic meat. The craze for wild boar meat has since dwindled, but their populations remain widespread and uncontrolled. Moreover, the full impact of the wild boar introduction on feral hog populations is still unknown. This study analyzes the skulls of porco-monteiro feral hogs from the 1990s, 2000s, and 2010s to assess possible morphological and functional variations along with skulls of wild boar and hybrids from Argentina, Uruguay, and Southern Brazil. The results indicate a trend of broadening of feral hog skulls at the coronal plane and a progressive reduction of the semispinalis capitis muscle scars over the decades. Biomechanical analysis denoted a decrease in head-elevation force that could affect the rooting performance of the latest feral hog morphotypes. Taken together, results show that wild boars likely influenced the evolution of the Pantanal feral hog skull. The magnitude of ecomorphological implications of these morphofunctional changes is unknown, as well as its effects in the Brazilian Pantanal wetland ecology.

Unraveling the synergistic promotion mechanism of Fe0 coupling phragmites australis biomass for nitrogen removal in coastal wetland: From low to moderate salinities

The simulated coastal constructed wetlands supplemented with Fe0 and phragmites australis (P.A) biomass (CW-M) were constructed to improve nitrogen removal under different salinities (0–15‰). Results showed that the denitrification performance of CW-M were improved significantly, with the higher NO3−-N removal of 72–94% and lower N2O emission flux, when compared with mono-P.A biomass(CW-bio), mono-Fe0 system (CW-Fe) and control system. The nitrogen removal showed a trend of first increasing (0‰–7‰) and then decreasing (7‰–15‰) with the highest NO3−-N removal of 94% and enhanced removal efficiency of 41%in CW-M. Fe0 and P.A biomass coupling could reduce the stress of salinity on denitrification. Batch experiments have demonstrated that Fe0 and P.A biomass could mutually stimulate more total organic carbon and total iron (TFe) release as electron donors for denitrification. Meanwhile, appropriate salinity could also promote the release of TFe. The typical heterotrophic denitrifying genera Bacillus and iron autotrophic denitrifying genera Thermomonas have the highest proportion in CW-M, with 21.83% and 0.10%, respectively. Fe0 and P.A biomass adding simultaneously promoted the carbon and iron metabolism, further enhancing the nitrogen metabolism process. The joint enhancement of autotrophic and heterotrophic denitrification contributes to NO3−-N removal in CW-M for treating saline, low C/N wastewater in coastal wetlands.

Spatiotemporal Dynamics and Drivers of Coastal Wetlands in Tianjin–Hebei over the Past 80 Years

Coastal wetland ecosystems are critical due to their diverse ecological and economic benefits, yet they have been significantly affected by human activities over the past century. Understanding the spatiotemporal changes and underlying factors influencing these ecosystems is crucial for developing effective ecological protection and restoration strategies. This study examines the Tianjin–Hebei coastal wetlands using topographic maps from the 1940s and Landsat satellite imagery from 1975, 2000, and 2020, supplemented by historical literature and field surveys. The aim is to analyze the distribution and classification of coastal wetlands across various temporal intervals. The findings indicate an expansion of the Tianjin–Hebei coastal wetlands from 7301.34 km2 in the 1940s to 8041.73 km2 in 2020. However, natural wetlands have declined by approximately 44.36 km2/year, while constructed wetlands have increased by around 53.61 km2/year. The wetlands have also become increasingly fragmented, with higher numbers of patches and densities. The analysis of driving factors points to human activities—such as urban construction, cultivated land reclamation, sea aquaculture, and land reclamation—as the primary contributors to these changes. Furthermore, the study addresses the ecological and environmental issues stemming from wetland changes and proposes strategies for wetland conservation. This research aims to enhance the understanding among researchers and policymakers of the dynamics and drivers of coastal wetland changes, as well as the major challenges in their protection, and to serve as a foundation for developing evidence-based conservation and restoration strategies.

World wetlands classification: a new hierarchic hydro-ecological approach

AbstractMany different approaches to classify wetlands at regional and global levels have been proposed, but their use of different classification parameters complicates comparisons of the results. Moreover, none of the international approaches cover global wetland variety with respect to size and environmental conditions. A comparison shows that hydrology is the only parameter that can be used for a hierarchic classification on a global scale. In the approach presented herein, differentiation between coastal, inland and anthropogenic wetlands is proposed. The use of higher classification units (systems, subsystems, orders, suborders and classes) is based on hydrological parameters. Wetlands are separated into small, simply structured types treated by all classification systems, and large wetscapes that, due to their complexity, are not. However, wetscapes represent well-defined landscape units, many of which are the focus of international organizations involved in wetland protection. They have to be treated using a holistic approach given the many interactions of their ecological subunits, their role in regional economies, their targeting by legislation and their value to humans. Considering the large gaps in knowledge about wetlands at a global scale, the new approach is a powerful tool for its classification, because it is flexible enough to include additional classification units, as required. Local classification systems can eliminate higher categories, which do not occur in their regions. Classification at lower rankings (functional units, subclasses, macrohabitats) can be introduced using additional classification parameters such as vegetation, soils and water chemistry. Examples from Brazil are provided.