Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Vegetation dynamics induced by climate change and human activities: Implications for coastal wetland restoration

Coastal wetlands are valuable ecosystems that have been gravely threatened by climate change and human activities. Understanding vegetation dynamics and relevant driving mechanisms is important for the management and restoration of coastal wetlands. Here, based on Landsat data and field surveys, the spatiotemporal variations in normalized difference vegetation index (NDVI) were analyzed for the Beidagang Wetland Nature Reserve in northern China to understand the vegetation response to climate change during periods with different human impacts (i.e., low-disturbance, high-disturbance, and recovery stages). The results showed that the average growing-season NDVI (NDVIgs) over the area exhibited a significant decreasing trend from 1984 to 2023 at -0.0025 a-1 (p < 0.001), even during the recovery stage (2014-2023); however, NDVIgs across the area revealed varying trends due to the interactive impacts of climate change and human activities. Specifically, NDVIgs showed significant increasing trends in less human disturbed areas due to rising temperature (T); whereas, this increasing trend was greatly weakened in human disturbed areas. During the recovery stage, the legacy impact of human activities, particularly the excavation of aquaculture ponds in the high-disturbance stage, persistently prohibited vegetation recovery; moreover, the increase in open water area due to ecological water replenishment also contributing to the declining NDVIgs. By comparison, appropriate restoration measures (e.g., constructing embankments and connecting drainage ditches) aided vegetation recovery during the same stage. This study demonstrates the interactive impacts of climate change and human activities on coastal wetland vegetation dynamics, which provides an important perspective for improving restoration efforts in coastal wetlands.

Decadal hydroclimatic changes in the Pantanal, the world's largest tropical wetland

The Pantanal, the world's largest tropical wetland, experienced unusual drying in 2000-2021, but the causes are poorly understood. Combining remotely sensed data of wetland extent and land cover with observed water level discharge and meteorological data, we quantify the relative contributions of climate and land use to changes in Pantanal wetland extent. Climate variability drove 96% of the runoff changes over four major hydroclimate regimes, including two wet (1951-1964; 1976-2000) and two dry (1965-1975; 2001-2021) periods. Reduced precipitation, runoff, and wetland shrinkage observed in 2001-2021 resembled the previous dry period (1965-1975), indicating decadal climatic variability. However, the higher aridity index in the recent period exacerbated the duration of the drought, and the rainfall-runoff relationship shifted over time, with more runoff for a given rainfall amount in recent periods. Wetland area is highly sensitive to climate variability, contracting to 25% of the maximum during dry years. Future warming and reduced rainfall will likely continue the recent drying trend, further reducing runoff, wetland area, and the Pantanal biodiversity.

Rise in wetland carbon uptake linked to increased potential evapotranspiration

Precisely assessing wetland net ecosystem productivity (NEP) is important for accurately evaluating global carbon budgets. However, constrained by the quality of observational data and insufficient understanding of driving mechanisms, assessments of China's wetland NEP still have considerable uncertainties. Therefore, this study assessed continuous observations from 30 eddy covariance flux towers across various wetland types in China and applied the random forest (RF) model to simulate the spatiotemporal dynamics of China's wetland NEP. The results showed that from 1982 to 2020, China's wetlands represented a net C-CO2 sink overall, with an average NEP of 21.61 ± 0.04 mg C m-2 h-1 and annual net C-CO2 absorption of 56.23 Tg C. Riverine and coastal wetlands had the highest NEP, while freshwater marshes had the lowest. From 1982 to 2020, the wetland NEP in China exhibited a significant increasing trend. Further analysis indicated that potential evapotranspiration (PET) is the main driving factor behind the significant increase in NEP in China's wetlands, with a clear threshold effect: NEP rises with PET up to a certain point (e.g., 160 mm), after which it declines. This study accurately quantified the spatiotemporal dynamics of China's wetland NEP and revealed the critical impact of PET on NEP, thus providing a new perspective for performing wetland carbon cycle research and formulating climate change mitigation strategies.

Warming-Induced Plant Species Shifts Lead to Substantial Losses of Wetland Soil Carbon

Wetlands are large reservoirs of soil organic carbon (SOC), storing one-third of global SOC within 6% of the land surface. However, the feedback direction and magnitude of wetland SOC storage to climate warming remain unclear. Here we present results from an 8-year (2014-2022) wetland warming experiment in the Yellow River Delta, revealing that wetland SOC storage responds to warming in a phase-dependent manner. We found that warming initially reduced both carbon input and output but did not change SOC storage. However, SOC storage abruptly decreased by 21.4% in 2020, which persisted over the following 2 years. This occurred mainly due to shifts in the biomass of dominant plant species (P. australis) under warming, reducing carbon input, increasing microbial carbon degradation, and resulting in microbial necromass carbon loss. These results highlight the critical role of dominant plant species in driving the wetland soil carbon cycle and its feedback to climate change.

To Understand the Elusive: How to Avoid the Disappearance of the Black Grouse at the Edge of Its Continuous Range?

Galliformes are one of the most rapidly declining groups of bird species in Europe. The black grouse belongs to a species closely related to the types of habitats that are disappearing due to environmental changes caused by man, the climate crisis, and an increase in the number of predator species. While the populations of this species in Northern and North-Eastern Europe are still relatively stable, in Central and Western Europe the black grouse is declining very quickly. For example, in Poland, there has been an approximately 100-fold decrease in its population over the last 50 years. However, there is a difference between the rate of decline in black grouse numbers in Central European lowlands and mountain refuges-for example, the Alps and the Carpathians. The European mountains, still offering habitats shaped by relatively severe climate, may soon be the only type of habitat for this species to survive in this part of the continent. Our study aimed to indicate the main environmental factors determining the occurrence of the species in a mountain refuge, on the southwestern border of this species' continuous range. Based on a comprehensive model containing data on land cover by vegetation, topography, and human disturbance, we assessed environmental factors that shape the probability of black grouse occurrence in one of its last refuges in Europe. Our results reveal a trend for black grouse to prefer habitats of an early succession stage, and those can only persist in specific climatic conditions, or thanks to active protection. Detailed knowledge of the habitat choice of an endangered species constitutes valuable data necessary to avoid the fragmentation of remaining patches of its habitat, to assess the state of the environment in times of climate crisis, and to protect its features that ensure and increase the survival of vulnerable species, such as black grouse.

An automatic classification method with weak supervision for large-scale wetland mapping in transboundary (Irtysh River) basin using Sentinel 1/2 imageries

Wetlands are essential ecosystems that play a significant role in biodiversity conservation and environmental stability. Monitoring their changes is crucial for understanding ecological dynamics and informing conservation strategies, particularly those in transboundary basins. This study introduces a novel automatic classification method for mapping and detecting wetland changes in the Irtysh River Basin. Utilizing Google Earth Engine (GEE) as the primary platform, this method integrates unsupervised classification, sample transfer techniques, and object-oriented random forest (OORF) algorithms to generate accurate training samples and delineate wetlands. Using Sentinel-1 and Sentinel-2 satellite data, we created high-resolution wetland distribution maps. The process begins with unsupervised classification to identify wetland inundation zones, followed by overlaying permanent water bodies and surface depressions to refine the sample set. Sample transfer, using spectral similarity metrics with the GWL_FCS30 product, further enhances the robustness of the training data. The selected features from Sentinel-1 and Sentinel-2 data, including spectral indices, phenological parameters, and textural features, were optimized, resulting in 18 optimal features for the OORF classification. The classification achieved a high overall accuracy of 96.96 %, with a sample accuracy of 98.1 %, and both User's and Producer's Accuracies consistently above 88 %. Spatiotemporal analysis of wetland changes from 2017 to 2023 revealed significant fluctuations, including a net loss of approximately 1,743.92 km2 of wetlands in the Irtysh River Basin. This study provides an effective and innovative method for large-scale wetland monitoring, offering valuable insights to support conservation and management efforts.

Developing and Validating Species Distribution Models for Wetland Plants Across Europe

Drainage, agricultural conversion, and climate change threaten wetlands and their unique biodiversity. Species distribution models (SDMs) can help to identify effective conservation measures. However, existing SDMs for wetland plants are often geographically limited, miss variables representing hydrological conditions, and neglect moss species, essential to many wetlands. Here, we developed and validated SDMs for 265 vascular plant and moss species characteristic of European wetlands, using environmental variables representing climate, soil, hydrology, and anthropogenic pressures. We validated the spatial predictions of the SDMs through cross-validation and against independent data from the Global Biodiversity Information Facility (GBIF). Further, we validated the niche optima of the species, as obtained from the modelled species response curves, with empirical niche optima. The spatial validation revealed good predictive power of the SDMs, especially for diagnostic mosses, for which we obtained median cross-validated values of the area under the curve (AUC) and true skill statistic (TSS) of 0.93 and 0.73, respectively, and a median true positive rate (TPR) based on GBIF records of 0.77. SDMs of diagnostic vascular plants performed well, too, with median AUC, TSS, and TPR of 0.91, 0.69, and 0.67, respectively. SDMs of non-diagnostic plants had the lowest performance, with median AUC, TSS, and TPR values of 0.84, 0.53, and 0.62, respectively. Correlations between modelled and empirical niche optima were typically in the expected direction. Climate variables, particularly the mean temperature of the coldest month, were the strongest predictors of species occurrence. At the same time, groundwater table depth was a significant predictor for diagnostic vascular plants but not for mosses. We concluded that our SDMs are suitable for predicting broad-scale patterns of wetland plant species distributions as governed by climatic conditions. Alternative or additional variables or a different modelling approach might be needed to represent better the local heterogeneity in the hydrological conditions of wetlands.

Carbon sequestration potential of wetlands and regulating strategies response to climate change

Wetlands are important carbon sinks for mitigating climate warming. In this paper, greenhouse gas (GHG) fluxes and carbon sequestration capacity of freshwater wetlands, coastal wetlands and constructed wetlands around the world are evaluated, and strategies to improve carbon sequestration by wetlands are proposed based on the main influencing factors. Air temperature and average annual rainfall are significantly positively correlated with CH4 flux and N2O flux in freshwater wetlands and coastal wetlands. While chemical oxygen demand (COD) and total nitrogen (TN) concentrations of influent are found to be the main factors affecting GHG fluxes in constructed wetlands. The main factors affecting wetland carbon storage include the presence and species of wetland vegetation, ecological water level, and ecological pattern. Strategies for protecting and restoring existing wetlands, creating new wetlands, and strengthening the carbon sequestration capacity of wetlands are proposed. Fully realizing the carbon sequestration potential of wetlands holds the prospect of a more effective and sustainable response to global climate change.

Global environmental change mediated response of wetland plants: Evidence from past decades

Wetland ecosystems are critically affected by global environmental changes, yet understanding the impact of these changes on wetland plants remains a challenge. This review article employs a comprehensive approach, including bibliographic analysis, utilization of various climate models for historical data retrieval, and extensive literature survey, to investigate the response of wetland plants to environmental shifts over the past decades. The analysis conducted in this study uncovers a multitude of climatic parameters that exhibit an influence on the dynamics of wetland vegetation. Results indicated a significant positive trend in atmospheric CO2 concentration, leading to increased water use efficiency in some plant species, particularly C3 plants. However, C4 plants did not show the same positive response. Nitrous oxide growth rate showed a weaker, less consistent trend than CO2, highlighting the need for further investigation into the complex factors influencing Nitrous oxide emissions from wetlands. Methane growth rate and global mean sea level demonstrated a strong positive linear trend. Ocean pH exhibited a statistically significant downward trend (acidification), while sea surface temperature showed a moderate but statistically significant upward trend. Glacier mass balance revealed a significant negative trend. Although some plants may benefit from increased CO2 initially, but the combined effects of rising sea levels, ocean acidification, and temperature changes pose substantial threats to the overall health and diversity of wetland plant life.

Research Status and Development Trend of Greenhouse Gas in Wetlands: A Bibliometric Visualization Analysis

With the intensification of global warming, wetland greenhouse gas (GHG) emissions have attracted worldwide attention. However, the scientific understanding of wetland GHGs is still limited. To gain a comprehensive and systematic understanding of the current research status and development trends in wetland GHGs. We selected 1627 papers related to wetland GHG research from the Web of Science Core Collection database and used the bibliometric visualization analysis method to reveal the annual publication, main core research forces, research hotspots, and trends in this field. The results showed that the research in this field shows a steady upward trend. United States research institutions and scholars play a key role in this field. The research on "climate change" based on three major wetland GHGs (carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) has been continuously gaining popularity. In recent years, "water" has become an emerging core topic. More and more studies have focused on enhancing wetland pollutant treatment capacity, improving wetland ecosystem productivity, maintaining water level stability, strengthening blue carbon sink function, exploring remote sensing applications in wetlands, and promoting wetland restoration to reduce GHG emissions. Furthermore, we discussed the influencing factors of the emission of CO2, CH4, and N2O in wetlands and summarized the potential methods to reduce GHG emissions. The findings provide scientific guidance and reference on wetland sustainable development and GHG emission reduction.

Mapping of water spread dynamics of a tropical Ramsar wetland of India for conservation and management

Wetlands are dynamic ecosystems vital for sustaining ecological health and development at regional and global scales. Geospatial tools have emerged as essential for managing wetland ecosystems. This study assessed the spatiotemporal dynamics of water spread in the Point Calimere Wetland, a coastal Ramsar site located along the Bay of Bengal, India, from 1984 to 2023. The analysis based on Global Surface Water Explorer (GSWE) and Normalized Difference Water Index (NDWI) derived from Landsat 5, 7, and 8 data revealed that 21% of the total wetland area showed an increasing trend. In comparison, 5.7% of the area showed a decreasing trend of surface water coverage, largely driven by erosion and climatic variability. The mean water spread increased from 119.47 km2 (2000-2003) to 160.88 km2 (2020-2023), with notable seasonal fluctuations. Among all seasons, the monsoon with the highest surge (41.1%) in water dynamics reported the largest water spread in 2020-2023 (221.87 km2). A moderate positive and negative relationship was noted between rainfall and water spread (r = 0.35) and temperature and water spread (r = - 0.43). A marked increase in habitat patches and edge density between 2000-2003 and 2020-2023 indicates the wetland's vulnerability to changing climatic conditions and the critical role of seawater intrusion, shoreline changes, and tidal forces in shaping its hydrological dynamics. The data presented on the historical water dynamics in this study is invaluable for the conservation planning and management of wetlands to support the associated coastal biodiversity and livelihood of the dependent communities.

Metagenomic Analysis Revealing the Impact of Water Contents on the Composition of Soil Microbial Communities and the Distribution of Major Ecological Functional Genes in Poyang Lake Wetland Soil

Poyang Lake is the largest freshwater lake in China, which boasts unique hydrological conditions and rich biodiversity. In this study, metagenomics technology was used to sequence the microbial genome of soil samples S1 (sedimentary), S2 (semi-submerged), and S3 (arid) with different water content from the Poyang Lake wetland; the results indicate that the three samples have different physicochemical characteristics and their microbial community structure and functional gene distribution are also different, resulting in separate ecological functions. The abundance of typical ANME archaea Candidatus Menthanoperedens and the high abundance of mcrA in S1 mutually demonstrate prominent roles in the methane anaerobic oxidation pathway during the methane cycle. In S2, the advantageous bacterial genus Nitrospira with ammonia oxidation function is validated by a large number of nitrification functional genes (amoA, hao, nxrA), manifesting in that it plays a monumental role in nitrification in the nitrogen cycle. In S3, the dominant bacterial genus Nocardioides confirms a multitude of antibiotic resistance genes, indicating their crucial role in resistance and their emphatic research value for microbial resistance issues. The results above have preliminarily proved the role of soil microbial communities as indicators predicting wetland ecological functions, which will help to better develop plans for restoring ecological balance and addressing climate change.

The increasing rate of net carbon uptake in Eurasia has been declining since the early 2000s

The analysis of terrestrial ecosystem carbon dynamics, based on scarce carbon flux observations or carbon flux products simulated by reanalysis meteorological data, has great uncertainties. A more accurate understanding of carbon dynamics in Eurasia was achieved by using a carbon flux dataset (CFD) from meteorological stations with quasi-observational characteristics. The growth of net carbon uptake of ecosystems over Eurasia has been decreasing since the early 2000s. The net ecosystem productivity (NEP) increased significantly with the growth rate of 8.7 × 10-3 g C m-2d-1 yr-1 in spring, summer, and autumn (SSA) during 2003-2011 (p < 0.05), which was correlated with the enhanced vegetation index (EVI) and land surface water index (LSWI). This growth was mostly in dry subhumid and humid regions. However, the change in Eurasian NEP was not significant after 2011. Additionally, about 79 % of the stations in Eurasia were in net carbon uptake in SSA, and net carbon emission stations were mainly located in southwestern Eurasia. The intensity of net carbon uptake was highest in the forest, with a mean carbon uptake of 1.73 ± 0.76 g C m-2d-1 in SSA during 2003-2018, and almost all stations demonstrated carbon uptake. During 2011-2018, the number of stations experiencing reduced NEP exceeded those with increased NEP, and this ratio was higher compared to 2003-2011, mainly due to the decrease in EVI and LSWI. The rate of NEP decline at stations with reduced NEP was 5.2 × 10-3 g C m-2d-1 yr-1 faster during 2011-2018 than in the previous period (p < 0.01). Most of the decreases in NEP during 2011-2018 occurred in cropland, grassland and urban land. The spatio-temporal dynamic analysis of Eurasian NEP could provide references for effective carbon management.

Greenhouse gas emissions from rotating biological contactors combined with hybrid constructed wetlands treating polluted river

The rotating biological contactors combined with hybrid constructed wetlands (R-HCWs) has promising treatment performance, however, concerns persisted regarding greenhouse gases (GHGs) emissions. In this study, GHGs in the R-HCWs was evaluated, and results revealed that R-HCWs facilitated nitrogen conversion and provided alternating oxygen environments, thereby promoting the reduction of N2O and CH4 emissions. Therefore, the comprehensive global warming potential (8.7±2.7 g CO2-eq·m-3·d-1) for handling unit volume of river water was low, thus, greater ecological benefits were achieved. The relative abundance of functional microorganisms such as Bacillus, Acinetobacter, Nitrospira and norank_f__norank_o__SBR1031, increased due to warm season, which promoted the nitrogen cycle and N2O emission reduction. Anammox and denitrifying bacteria showed significantly correlated with N2O and CH4 emissions (p < 0.01). This study provides valuable insights for the potential adoption of biological and ecological integrated treatment approach optimized for improving water and mitigating GHGs emissions.

Microbiology of wetlands and the carbon cycle in coastal wetland mediated by microorganisms

Wetlands are highly diverse and productive and are among the three most important natural ecosystems worldwide, among which coastal wetlands are particularly valuable because they have been shown to provide important functions for human populations. They provide a wide variety of ecological services and values that are critical to humans. Their value may increase with increased use or scarcity owing to human progress, such as agriculture and urbanization. The potential assessment for one coastal wetland habitat to be substituted by another landscape depends on analyzing complex microbial communities including fungi, bacteria, viruses, and protozoa common in different wetlands. Moreover, the number and quality of resources in coastal wetlands, including nutrients and energy sources, are also closely related to the size and variety of the microbial communities. In this review, we discussed types of wetlands, how human activities had altered the carbon cycle, how climate change affected wetland services and functions, and identified some ways to promote their conservation and restoration that provide a range of benefits, including carbon sequestration. Current data also indicated that the coastal ocean acted as a net sink for atmospheric carbon dioxide in a post-industrial age and continuous human pressure would make a major impact on the evolution the coastal ocean carbon budget in the future. Coastal wetland ecosystems contain diverse microbial communities, and their composition of microbial communities will tend to change rapidly in response to environmental changes, as can serve as significant markers for identifying these changes in the future.

Microplastics exacerbate the ecological risk of antibiotic resistance genes in wetland ecosystem

Wetlands are vital components of the global ecosystem, significantly influencing the retention and dissemination of microplastics (MPs) and antibiotic resistance genes (ARGs). However, the effects of different types of MPs on the environmental dynamics of ARGs within these ecosystems remain poorly understood. This study focused on the distribution and composition of ARGs associated with two primary types of MPs-polyethylene and polypropylene-within the Poyang Lake wetland, the largest freshwater lake in China, utilizing metagenomic analysis. The findings demonstrated that the bacterial communities and ARG profiles in the plastisphere were markedly distinct from those in the surrounding water. Specifically, thirteen opportunistic pathogens and forty subtypes of ARGs, primarily related to multidrug, bacitracin, and β-lactam resistance, were identified in the plastisphere. Notably, polyethylene exhibited four times more specific ARG subtypes than polypropylene. Procrustes analysis combined with network analysis indicated a lack of strong correlation between ARG abundance and bacterial populations, suggesting potential horizontal transfer of ARGs within the microbiota of the plastisphere. Additionally, three novel and functional β-lactamase genes were identified within this environment. This investigation highlights the role of MPs as reservoirs for ARGs, facilitating their exchange and posing risks to both ecological integrity and human health, thereby underscoring the need for increased attention in future research efforts.

Iron-bound organic carbon declined after estuarine wetland reclamation into paddy fields

Iron-bound organic carbon (Fe-OC) is a main pathway for the long-term maintenance of soil organic carbon (SOC), but research on its mechanism is still relatively weak. We investigated the coupling relationships among iron (Fe), carbon (C) and Fe-reducing bacteria (FeRB) in the soil of a reclaimed paddy field in comparison with natural Phragmites australis wetland in the Minjiang River estuary in southeastern China. The results showed that conversion of P. australis wetland to paddy cultivation changed the soil redox process. After reclamation, soil Fe(II), Fe(III), HCl-Fet, free iron oxide (Fed) and amorphous iron (Feo) contents and Fe(III)/Fe(II) decreased significantly (p < 0.05), while the content of complexed iron (Fep) increased. Nonmetric multidimensional scaling analysis (NMDS) demonstrated variability in FeRB across soil types (r = 0.900, p = 0.001). The lower Fe-OC concentration in soil after wetland reclamation may be the result of Fe reduction by dissimilatory FeRB (e.g., Bacillus, Anaeromyxobacter). On average, both Fe-OC and SOC contents decreased significantly (p < 0.05), while the contribution of Fe-OC to total SOC (fFe-OC) increased significantly (p < 0.05), after conversion to paddy cultivation. Structural equation modeling (SEM) showed that SOC, dissolved organic C, and Fe-OC were affected by FeRB and the speciation of Fe. In addition, Fe (III) concentration affected SOC concentration (r = 0.60, p < 0.05) and DOC concentration (r = 0.58, p < 0.05), and Fed affected DOC concentration (r = 0.69, p < 0.05). We conclude that after rice field reclamation in estuarine wetlands, Fe-reducing bacteria can mediate iron-bonded organic C decoupling, affecting SOC stabilization.

Looking beyond the surface: Understanding the role of multiple stressors on the eutrophication status of the Albufera Lake (Valencia, Spain)

Aquatic ecosystems face significant impacts from human-related stressors, demanding a deep understanding of their dynamics and interactions for effective management and restoration. The Albufera Lake (Valencia, Spain) presents a complex scenario of multiple interacting stressors affecting its eutrophic status. In this study, we compiled a 50-year dataset and used Generalized Additive Models (GAMs) to analyse the dynamics of the main stressors affecting the ecological status of the Albufera Lake. Then, we assessed their individual and combined effects on eutrophication using chlorophyll-a concentration as a proxy and provided recommendations to enhance water quality. Overall, we found a decrease in annual water inflow and a clear effect of rice cultivation on the seasonal patterns of the Lake's residence time. Our analysis also shows an increase of average water temperature of 2 °C for the last 50 years, and an increase in the frequency and severity of heat waves. In contrast, we found a slightly negative long-term trend in conductivity, despite the occurrence of seasonal peaks in summer. Regarding nutrients, we identified a clear reduction of total phosphorus (from 1.08 mg/L in 1987 to 0.20 mg/L in 2022), while nitrate concentrations have been rather stable. Our results also point at an increase of toxic pressure exerted by organic and inorganic contaminants during the last years, with seasonal toxicity peaks occurring during rice field drainage periods. The main stressors affecting the chlorophyll-a levels were found to be temperature, water scarcity, and nitrate concentration as well as the interactions between temperature and conductivity, conductivity and nitrate, conductivity and water scarcity, and nitrate and total phosphorus. We found that stressor interactions are highly dynamic and result in synergistic and antagonistic effects that vary according to different stressor levels. Finally, our GAM framework points to two potential scenarios: increasing freshwater inflows or deregulating hydrology to allow seawater exchange, which are key for improving the ecological status of the Albufera Lake in the short-term.

Quantitative assessment of the key drives shaping the long-term dynamics of geographically isolated wetlands: A case study within the Nenjiang River Basin, Northeast China

Geographically isolated wetlands (GIWs) offer a diverse array of ecosystem services and contribute largely to landscape functions. Numerous studies have documented the substantial pressures on wetland ecosystems from both natural changes and human activities worldwide. However, the quantification of these impacts on GIWs remains scarce. This study presents an assessment of the spatiotemporal dynamics of GIWs in the downstream portion of the Nenjiang River Basin, Northeast China, over a 38-year period (1978-2015). We quantitatively evaluated the impacts of anthropogenic activities and natural changes using a five-stage wetland dataset (1978, 1990, 2000, 2008, and 2015) and four-stage (1990, 2000, 2010, and 2015) land use datasets. Our findings indicate that 86% of the GIWs in the study area have vanished, primarily replaced by unused land (28.39%) and farmland (54.90%). Anthropogenic activities were identified as the main cause of wetland loss from 1978 to 2008, whereas natural changes have played a more significant role in recent years of GIWs. Considering the ongoing regional trends of warming and drying, it is imperative to conserve and restore GIWs to maintain their ecosystem services for a broad spectrum of beneficiaries.

Metagenomics Insight into Veterinary and Zoonotic Pathogens Identified in Urban Wetlands of Los Lagos, Chile

Wetlands are ecosystems that are essential to ecological balance and biodiversity; nevertheless, human activity is a constant threat to them. Excess nutrients are caused by intensive livestock and agricultural operations, pollution, and population growth, which in turn leads to uncontrolled microbiological development. This impairment in water quality can constitute a risk to animal, human, and environmental health. To thoroughly characterize the microbial communities, shotgun metagenomics was used to characterize the taxonomic and functional pattern of microorganisms that inhabit urban wetlands in the Los Lagos Region of Chile. The main objective was to identify microorganisms of veterinary relevance, assess their potential antibiotic resistance, and characterize the main virulence mechanism. As expected, a high diversity of microorganisms was identified, including bacteria described as animal or human pathogens, such as Pasteurella multocida, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Also, a diverse repertory of antimicrobial-resistant genes (ARGs) was detected in metagenomic assembled sequences and inside the sequence of mobile genetic elements, genes that confer mainly resistance to beta-lactams, consistent with the families of antibiotics most used in Chile. In addition, a diverse collection of virulence mechanisms was also identified. Given the significance of the relationship between environmental, animal, and human health-a concept known as One Health-there is a need to establish molecular surveillance programs that monitor the environmental biohazard elements using molecular tools. This work is the first report of the presence of these harmful biological elements in urban wetlands subjected to anthropogenic pressure, located in the south of Chile.

Effect of channel morphological changes on wetland transformation

Keeping aside the traditional approaches to investigating floodplain wetland transformation, the current study investigated various aspects of it through changes in river channel morphology and drainage pattern. The study analyzed wetland transformation using satellite image-based machine learning and intensive fieldwork. Ordinary Least Square (OLS) regression was applied to identify dominant influencing factors among 24 contributing factors under six clusters to eight dependent phenomena of transformation. The result showed that 57 % of wetland area lost since 1991, and existing wetland has also experiencing hydrological scarcity. From 1991 to 2021, the area under low water depth (<1 m.) inflated from 18.55 % to 50.54 %, the hydro-period narrowed down, and the appearance of water become inconsistent. The OLS result showed that changes in channel morphology (bottle neck channel, embankment-driven carrying capacity enhancement, etc.), interruptions in river and wetland connecting channels (source closure, breaching the continuity, conversion in to agricultural land, etc.), and changes in flood ambience (regulated by dam construction, erection of embankments, etc.) majorly contributed to wetland transformation. Very high explainability was found in the cases of rate of wetland loss, decreasing water depth under greater depth, narrowing hydro-period (R2 > 0.9). The findings of this work would be a good policy document for floodplain wetland management.

Addressing pollution challenges for enterprises under diverse extreme climate conditions: artificial intelligence-driven experience and policy support of top Chinese enterprises

Introduction

This study investigates the experiences of leading Chinese companies in environmental conservation under varying extreme climate conditions, focusing on the role of artificial intelligence (AI) and governmental assistance.

Methods

A survey was conducted involving 200 participants to assess recognition and endorsement of AI's role in environmental protection and to explore the adoption of AI technologies by firms for enhancing environmental management practices.

Results

The survey revealed widespread recognition of Tencent's green initiatives and strong support for AI's role in environmental protection. Many firms are considering adopting AI technologies to optimize energy management, deploy intelligent HVAC systems, and improve the operations of data centers and smart lighting systems.

Discussion

The findings highlight a strong belief in AI's potential to advance environmental protection efforts, with a call for increased governmental support to foster this development. The study underscores the importance of a partnership between businesses and governments to leverage AI for environmental sustainability, contributing significantly to conservation efforts.

Spatiotemporal patterns of greenhouse gas fluxes in the subtropical wetland ecosystem of Indian Himalayan foothill

The study characterized the temporal and spatial variability in greenhouse gas (GHG) fluxes (CO2, CH4, and N2O) between December 2020 and November 2021 and their regulating drivers in the subtropical wetland of the Indian Himalayan foothill. Five distinct habitats (M1-sloppy surface at swamp forest, M2-plain surface at swamp forest, M3-swamp surface with small grasses, M4-marshy land with dense macrophytes, and M5-marshy land with sparse macrophytes) were studied. We conducted in situ measurements of GHG fluxes, microclimate (AT, ST, and SMC(v/v)), and soil properties (pH, EC, N, P, K, and SOC) in triplicates in all the habitat types. Across the habitats, CO2, CH4, and N2O fluxes ranged from 125 to 536 mg m-2 h-1, 0.32 to 28.4 mg m-2 h-1, and 0.16 to 3.14 mg m-2 h-1, respectively. The habitats (M3 and M5) exhibited higher GHG fluxes than the others. The CH4 flux followed the summer > autumn > spring > winter hierarchy. However, CO2 and N2O fluxes followed the summer > spring > autumn > winter. CO2 fluxes were primarily governed by ST and SOC. However, CH4 and N2O fluxes were mainly regulated by ST and SMC(v/v) across the habitats. In the case of N2O fluxes, soil P and EC also played a crucial role across the habitats. AT was a universal driver controlling all GHG fluxes across the habitats. The results emphasize that long-term GHG flux monitoring in sub-tropical Himalayan Wetlands has become imperative to accurately predict the near-future GHG fluxes and their changing nature with the ongoing climate change.

Climate risk and green total factor productivity in agriculture: The moderating role of climate policy uncertainty

In light of the escalating global warming and the escalating frequency of extreme weather events, the agricultural sector, being a fundamental and pivotal industry worldwide, is encountering substantial challenges due to climate change. Using Chinese provincial panel data for 2000-2021, this paper utilizes a two-way fixed-effect model to investigate the impact of Climate Risk (CR) on green total factor productivity in agriculture (AGTFP), with China's climate policy uncertainty (CPU) being introduced as a moderating variable within the research framework to scrutinize its influence in this context. The findings reveal a noteworthy adverse effect of CR on AGTFP, further exacerbated by CPU. Heterogeneity analysis results show that there is a clear regional variation in the effect of CR on AGTFP across different Chinese regions, with CR significantly inhibiting AGTFP development in the northern regions and provinces in major grain producing regions. Consequently, there is a pressing necessity to bolster the establishment of climate change monitoring infrastructures, devise tailored climate adaptation strategies at a regional level, and enhance the clarity and predictability of climate policies to fortify the resilience and sustainability of agricultural production systems.

Factors governing the dynamics of soil organic carbon and nitrogen in wetlands undergoing management changes in a semi-arid region

Soil organic carbon and nitrogen play pivotal roles as indicators of soil quality and ecological functioning in wetlands. The escalating impact of human activities and climate change has led to a severe degradation of wetland soils, particularly in semi-arid regions. However, an understanding of the factors governing the dynamics of total soil organic carbon (TSOC) and total soil nitrogen (TSN) in semi-arid areas remains elusive, impeding a comprehensive understanding of wetland ecological functions. The present study investigated variations in TSOC and TSN content as well as vegetation and soil physicochemical properties under five different land management practices (mowed wetlands, mowed and slightly grazed wetlands, moderately grazed wetlands, heavily grazed wetlands, and natural wetlands unaffected by human interference) in the semi-arid Songnen Plain region of China. The results revealed significant decreases in TSOC and TSN content within managed wetlands compared to natural wetlands. Moreover, positive correlations were observed between pairs of SOC-TN or their storage values for SOC (TSOC)-TN (TSN). Furthermore, TSOC and TSN exhibited significant positive associations with aboveground and belowground biomass levels, stem C:N, stem C:P, soil C:P, and soil N:P. Additionally, redundancy analysis indicated that species diversity accounted for 37.4% of the variations in TSOC-TSN while belowground biomass accounted for 8.5% of the variations. Furthermore, nutrient content within stems (particularly N content and C:P) contributed to a 37.2% variation in TSOC and TSN whereas root nutrient content (especially N:P, C:N, and C:P) contributed to a 15.3% variation. Soil C:P, C:N, and total phosphorous (TP) content accounted for 65.7%, 9.6%, and 7.5% of variations of TSOC and TSN, respectively. Besides, variation partitioning analysis revealed that plant community characteristics, community nutrient content, and soil physicochemical properties collectively influenced the dynamics of TSOC and TSN. Among these factors, soil physicochemical properties emerged as the primary drivers of carbon and nitrogen dynamics in degraded wetlands in semi-arid regions. The impact on TSN was more pronounced than that of TSOC. This study provides valuable insights for understanding the processes and mechanisms underlying carbon and nitrogen accumulation in degraded wetlands, facilitating the development of regionally adaptive management plans under different management practices.

Assessing the Impact of Anthropogenically Modified Land Uses on Wetland Health: Case of Witbank Dam Catchment in South Africa

Wetlands are critical ecological infrastructures that improve water quality, serve as habitat for fish and other aquatic life, accumulate floodwaters, and maintain surface water flow during dry periods. However, the health of wetlands has been compromised by anthropogenic activities that affect the constant supply of ecosystem services. This study assessed the impact of anthropogenically modified land use on wetland health in the Witbank Dam Catchment in South Africa, whose land use has been severely modified for agriculture and mining purposes. The study developed a model linking surface runoff generated in the catchment with land use and wetland typology to comprehend diffuse pollution from pollution-source land uses. Runoff data and related wetland spatial information were processed and analysed in a Geographic Information System (GIS) to estimate pollutants (agricultural nutrients and acid mine drainage) from runoff detained and released by wetlands. The analysis facilitated the assessment of the value of wetlands in enhancing water quality, as well as human and environmental health. The runoff volume from pollution-source land uses (urban areas, farmlands, and mining) was used to evaluate annual pollution levels. Wetland types are ranked according to their efficiency levels to filter pollutants. The assumption is that the difference between filtered and unfiltered runoff is the quantity of polluted runoff water discharged into the river system. The analysis has shown that 85% of polluted runoff generated in the catchment ends up in the river system. An important observation is that although wetlands have a substantial ability to absorb excess pollutants, they have finite boundaries. Once they reach their full holding capacity, they can no longer absorb any further pollutants. The excess is discharged into the river system, risking human and environmental health. This explains why the Limpopo River is heavily polluted resulting in the death of fish, crocodiles and other aquatic life.

Aquatic Condition Index: optimization of a rapid wetland assessment tool for evaluating urban wetland health

Urbanization poses significant threats to wetland ecosystems, leading to habitat loss, hydrological alterations, and the introduction of invasive species that adversely affect essential ecosystem services. This widespread threat underscores the need to develop a robust management tool for gauging urban wetland health. The Aquatic Condition Index (ACI) was developed as a diagnostic tool for monitoring urban wetland health in Calgary, Alberta, Canada. The ACI evaluates wetland health by incorporating functional indicators (i.e., hydrological, ecological, and water quality functions) chosen by scientific experts to provide municipal wetlands with relative condition scores that can inform citywide habitat management budgeting and prioritization. Gathering the data necessary to generate wetland indicators for the ACI requires substantial financial resources, time, and a high degree of analytical expertise for data collection (e.g., field surveys). This investigation aimed to enhance the widespread applicability and cost-efficiency of wetland monitoring by optimizing the ACI. This optimization entailed a sensitivity-driven indicator reduction, which strategically minimizes the number of indicators essential for ACI calculations. Our findings demonstrate that the refined selection of indicators produces comparable results to the original ACI. This highlights the potential of transitioning to more rapid and cost-efficient monitoring methods, creating a streamlined approach to enhance the efficiency of monitoring and assessment processes. Ultimately, this approach can facilitate long-term urban wetland assessments and promote the sustainability and management of these vital urban features .

Supplementary Information

The online version contains supplementary material available at 10.1007/s11252-024-01596-0.

Greenhouse gases emissions and carbon budget estimation in horizontal subsurface flow constructed wetlands with different plant species

Constructed wetlands (CWs) are pivotal for wastewater treatment due to their high efficiency and numerous advantages. The impact of plant species and diversity on greenhouse gas (GHG) emissions from CWs requires a more comprehensive evaluation. Moreover, controversial perspectives persist about whether CWs function as carbon sinks or sources. In this study, horizontal subsurface flow (HSSF) CWs vegetated with Cyperus alternifolius, Typhae latifolia, Acorus calamus, and the mixture of these three species were constructed to evaluate pollutant removal efficiencies and GHG emissions, and estimate carbon budgets. Polyculture CWs can stably remove COD (86.79 %), NH4+-N (97.41 %), NO3--N (98.55 %), and TP (98.48 %). They also mitigated global warming potential (GWP) by suppressing N2O emissions compared with monoculture CWs. The highest abundance of the Pseudogulbenkiania genus, crucial for denitrification, was observed in polyculture CWs, indicating that denitrification dominated in nitrogen removal. While the highest nosZ copy numbers were observed in CWs vegetated with Cyperus alternifolius, suggesting its facilitation of denitrification-related microbes. Selecting Cyperus alternifolius to increase species diversity is proposed for simultaneously maintaining the water purification capacity and reducing GHG emissions. Carbon budget estimations revealed that all four types of HSSF CWs were carbon sinks after six months of operation, with carbon accumulation capacity of 4.90 ± 1.50 (Cyperus alternifolius), 3.31 ± 2.01 (Typhae latifola), 1.78 ± 1.30 (Acorus calamus), and 2.12 ± 0.88 (polyculture) kg C/m2/yr. This study implies that under these operation conditions, CWs function as carbon sinks rather than sources, aligning with carbon peak and neutrality objectives and presenting significant potential for carbon reduction efforts.

Methane emissions and microbial communities under differing flooding conditions and seasons in littoral wetlands of urban lake

Wetlands are the largest natural sources of methane (CH4) emissions worldwide. Littoral wetlands of urban lakes represent an ecotone between aquatic and terrestrial ecosystems and are strongly influenced by water levels, environmental conditions, and anthropogenic activities. Despite these littoral zones being potential "hotspots" of CH4 emissions, the status of CH4 emissions therein and the role of physicochemical properties and microbial communities regulating these emissions remain unclear. This study compared the CH4 fluxes, physicochemical properties, and CH4-cycling microbial communities (methanogens and methanotrophs) of three zones (a non-flooded supralittoral zone, a semi-flooded eulittoral zone, and a flooded infralittoral zone) in the littoral wetlands of Lake Pipa, Jiangsu Province, China, for two seasons (summer and winter). The eulittoral zone was a CH4 source (median: 11.49 and 0.02 mg m-2 h-1 in summer and winter, respectively), whereas the supralittoral zone acted as a CH4 sink (median: -0.78 and -0.09 mg m-2 h-1 in summer and winter, respectively). The infralittoral zone shifted from CH4 sink to source between the summer (median: -10.65 mg m-2 h-1) and winter (median: 0.11 mg m-2 h-1). The analysis of the functional genes of methanogenesis (mcrA) and methanotrophy (pmoA) and path analysis showed that CH4 fluxes were strongly regulated by biotic factors (abundance of the mcrA gene and alpha diversity of CH4-cycling microbial communities) and abiotic factors (ammonia nitrogen, moisture, and soil organic carbon). In particular, biotic factors had a major influence on the variation in the CH4 flux, whereas abiotic factors had a minor influence. Our findings provide novel insights into the spatial and seasonal variations in CH4-cycling microbial communities and identify the key factors influencing CH4 fluxes in littoral wetlands. These results are important for managing nutrient inputs and regulating the hydrological regimes of urban lakes.

Spatial and temporal variation of net primary productivity of herbaceous marshes and its climatic drivers in China

Herbaceous marshes are widely distributed in China and are vital to regional ecological security and sustainable development. Vegetation net primary productivity (NPP) is a vital indicator of vegetation growth. Climatic change can significantly affect NPP, but variations in NPP of herbaceous marsh and their responses to climate change in China remain unclear. Using meteorological data and MODIS NPP data during 2000-2020, this study analyzed the spatial and temporal variations of NPP and their responses to climate change in Chinese herbaceous marshes. We found that the annual NPP of herbaceous marshes in China increased significantly at a rate of 3.34 g C/m2/a from 2000 to 2020, with an average value of 336.60 g C/m2. The increased annual total precipitation enhanced the national average NPP, whereas annual mean temperature had no significant effect on the national average NPP. Regionally, precipitation had a significant positive effect on the NPP in temperate semi-arid and arid and temperate semi-humid and humid marsh regions. For the first time, we discovered asymmetry effects of daytime and nighttime temperatures on NPP in herbaceous marshes of China. In temperate humid and semi-humid marsh regions, increased summer daytime temperature decreased the NPP while increased summer nighttime temperature increased the NPP. In the Tibetan Plateau, increased autumn daytime temperature, as well as summer daytime and nighttime temperatures could increase the NPP of herbaceous marshes. This study highlights the different influences of seasonal climate change on the NPP of herbaceous marshes in China and indicates that the differential effects of daytime and nighttime temperatures should be considering in simulating the NPP of herbaceous marshes in terrestrial ecosystem models, especially under the background of global asymmetric diurnal warming.

Nighttime warming and nitrogen addition effects on the microclimate of a freshwater wetland dominated by Phragmites australis

The critical impacts of microclimate on carbon (C) cycling have been widely reported. However, the potential effects of global change on wetland microclimate remain unclear, primarily because of the absence of field manipulative experiment in inundated wetland. This study was designed to examine the effects of nighttime warming and nitrogen (N) addition on air, water, and sediment temperature and also reveal the controlling factors in a Phragmites australis dominated freshwater wetland on the North China Plain. Nighttime warming increased daily air, water, and sediment temperature by 0.24 °C, 0.27 °C, and 0.36 °C, respectively. The diurnal temperature range of water was decreased by 0.44 °C under nighttime warming, whereas warming had no effect on diurnal temperature range of air and sediment. In addition, N addition caused a reduction of 0.20 °C and 0.14 °C in daily water and sediment temperature by increasing vegetation coverage. There was a significant interaction between nighttime warming and N addition on water temperature. Furthermore, the vapor pressure deficit is the main factor affecting the extent of the warming-induced increases in air temperature. The changes of height and leaf area index of Phragmites australis are responsible for the cooling effects in the N addition plots. This study provides empirical evidence for the positive climate warming - microclimate feedback in freshwater wetland. However, N deposition leads to decreased water and sediment temperature. Our findings highlight the importance of incorporating the differential impacts of nighttime warming and N addition on air, water, and sediment temperature into the predictions of wetland C cycling responses to climate change.

Elemental mercury production from contaminated riparian soil suspensions under air and nitrogen bubbling conditions

The dynamic change of redox conditions is a key factor in emission of elemental mercury (Hg0) from riparian soils. The objective of this study was to elucidate the influences of redox conditions on Hg0 emission from riparian soils. Soil suspension experiments were conducted to measure Hg0 emission from five Hg-contaminated soil samples in two redox conditions (i.e., treated with air or with N2). In four of the five samples, Hg0 emission was higher in air treatment than on N2 treatment. Remaining one soil, which has higher organic matter than other soils, showed no distinct difference in Hg0 production between air and N2 treatment. In soil suspensions subject to N2 treatment, the dissolved organic carbon (DOC) and Fe2+ concentrations were 3.38- to 1.34-fold and 1.44- to 2.28-fold higher than those in air treatment, respectively. Positive correlations were also found between the DOC and Fe2+ (r = 0.911, p < 0.01) and Hg2+ (r = 0.815, p < 0.01) concentrations in soil solutions, suggesting Fe2+ formation led to the release of DOC, which bound to Hg2+ in the soil and, in turn, limited the availability of Hg2+ for reduction to Hg0 in N2 treatment. On the other hand, for remaining one soil, more Hg2+ might be adsorbed onto the DOM in the air treatment, resulted in the inhibition of Hg0 production in air treatment. These results imply that the organic matter is important to prevent Hg0 production by changing redox condition. Further study is needed to prove the role of organic matter in the production of Hg0.

CH4 control and nitrogen removal from constructed wetlands by plant combination

Global warming trend is accelerating. This study proposes a green and economical methane (CH4) control strategy by plant combination in constructed wetlands (CWs). In this study, a single planting of Acorus calamus L. hybrid constructed wetland (HCW-A) and a mixed planting of Acorus calamus L. and Eichhornia crassipes (Mart.) Solms hybrid constructed wetland (HCW-EA) were constructed. The differences in nitrogen removal performance and CH4 emissions between HCW-A and HCW-EA were compared and analyzed. The findings indicated that HCW-EA demonstrated significant improvements over HCW-A, with NH4+-N and TN removal rates increasing by 21.61% and 16.38% respectively, and CH4 emissions decreased by 43.36%. The microbiological analysis results showed that plant combination promoted the enrichment of Proteobacteria, Alphaproteobacteria and Bacillus. More nitrifying bacteria carrying nxrA genes and denitrifying bacteria carrying nirK genes accelerated the nitrogen transformation process. In addition, the absolute abundance ratio of pmoA/mcrA increased, reducing the release of CH4.

Diversity and Population Sizes of Wintering Waterbirds in the Wetlands of the Saïss-Middle Atlas Region (North-Central Morocco): Main Survival Factors and Evaluation of Habitat Loss

Moroccan wetlands host up to half a million wintering birds and provide a stopover for tens of thousands of migrants, while they are inhabited by few nesting species. Most of this avifauna prefers to use the large coastal wetlands or reservoirs, while many species are dispersed across hundreds of small inland wetlands of various types. In this study, we monitored the wintering avifauna of 11 wetlands of the Saïss plain and its adjacent Atlas Mountains (north-center of Morocco), during six wintering seasons (2017-2018 to 2022-2023), with the objective of assessing the importance of this region as a waterbird wintering area. Using the richness of the species, we determine the bird population changes during this pentad and between the different types of wetlands (natural, human-made, and natural wetlands). During this study, we recorded 51 species, belonging to 17 families, among which exist four remarkable birds: the endangered Oxyura leucocephala, the vulnerable Aythya ferina and the near-threatened Aythya nyroca and Limosa limosa. Bird diversity is higher in human-made ecosystems than in peri-urban and natural ecosystems, while the populations' size is similar in urban and non-urban wetlands. With regard to bird conservation, these inland wetlands, mainly the small ones, are threatened by recurrent droughts and various anthropic stressors, which we describe using our observations of the two last decades (2003-2023). The loss of habitat is significant, reaching 348.5 hectares, while the impacts of reduced precipitation and temperature increase are particularly evident in the mountainous natural lakes.

Analysis of the evolution of water culture and water security in the Weihe River Basin over a 100 year-period

The significance of water culture in addressing water crises and ensuring water security has garnered considerable attention, emerging as a focal point in global change and water science research. Water culture is a societal adaptation to changes in hydrological systems. However, this needs to be acknowledged within contemporary discourse on water security governance. This study utilized historical policy document data from many sources, including local municipal records from Shaanxi and Gansu, and water conservancy records. It aimed to identify the significant nodes and stages of policy transformation in the Weihe River Basin (WRB) during the last century (1949-2020). This study employed a content analysis method to elucidate the evolutionary patterns of water culture in the study region during the previous century. Drawing on the co-evolution framework, our investigation delved into the reciprocal relationship between changes in water culture and the evolution of water security in the WRB. Our findings indicated that water culture transformation in the WRB has undergone four significant stages: the Disaster-Resistant Hydraulic (1949-1966), Irrigation Hydraulic (1967-1998), Resources Hydraulic (1999-2010), and Ecological Hydraulic (2011-2020) phases. Water security assessment showed that policy attention varied across the different stages. The disaster-resistant hydraulic phase primarily addressed water-related disaster concerns, whereas the irrigation hydraulic phase emphasized the scarcity of water resources. The resource hydraulic phase focused on ensuring the security of the water environment, while the ecological hydraulic phase placed emphasis on safeguarding water sustainability. Moreover, we found that prevailing water policies prioritize resolving isolated issues; however, water security is a multifaceted systemic matter that requires a comprehensive approach. This study has the potential to offer policy makers a more comprehensive and systematic perspective, enabling them to enhance their understanding of the underlying nature of the problems. Additionally, this study can assist in developing future water security policies.

Climate change will reduce North American inland wetland areas and disrupt their seasonal regimes

Climate change can alter wetland extent and function, but such impacts are perplexing. Here, changes in wetland characteristics over North America from 25° to 53° North are projected under two climate scenarios using a state-of-the-science Earth system model. At the continental scale, annual wetland area decreases by ~10% (6%-14%) under the high emission scenario, but spatiotemporal changes vary, reaching up to ±50%. As the dominant driver of these changes shifts from precipitation to temperature in the higher emission scenario, wetlands undergo substantial drying during summer season when biotic processes peak. The projected disruptions to wetland seasonality cycles imply further impacts on biodiversity in major wetland habitats of upper Mississippi, Southeast Canada, and the Everglades. Furthermore, wetlands are projected to significantly shrink in cold regions due to the increased infiltration as warmer temperature reduces soil ice. The large dependence of the projections on climate change scenarios underscores the importance of emission mitigation to sustaining wetland ecosystems in the future.

Nexus of food waste and climate change framework: Unravelling the links between impacts, projections, and emissions

This communication explores the intricate relationship between food waste and climate change, considering aspects such as impacts, projections, and emissions. It focuses on the pressing issue of waste generation and its potential consequences if current trends persist, and emphasises the importance of efficient solid waste management in improving environmental quality and fostering economic development. It also highlights the challenges faced by developing countries in waste collection and disposal, drawing comparisons with the waste utilisation methods used by developed nations. The review delves into the link between food waste and climate change, noting the paradoxical situation of food wastage against the backdrop of global hunger and malnutrition. It underscores the scientific evidence connecting food waste to climate change and its implications for food security and climate systems. Additionally, it examines the environmental burden imposed by food waste, including its contribution to greenhouse gas emissions and the depletion of resources such as energy, water, and land. Besides environmental concerns, this communication also highlights the ethical and socioeconomic dimensions of food waste, discussing its influence on Sustainable Development Goals, poverty, and social inequality. The communication concludes by advocating for collective action and the development of successful mitigation strategies, technological solutions, and policy interventions to address food waste and its climate impacts. It emphasises the need for collaboration, awareness, and informed decision-making to ensure a more sustainable and equitable future.

Reassessing the greenhouse effect of biogenic carbon emissions in constructed wetlands

Biogenic carbon emissions, including carbon dioxide (CO2) and methane (CH4), have emerged as a major concern during organic pollutant degradation within constructed wetlands (CWs). Since these organic compounds primarily originate from the photosynthetic fixation of atmospheric CO2, it potentially introduces uncertainty when assessing the greenhouse effect of biogenic carbon emissions in CWs based on direct field observations. To objectively assessing this effect, this study proposed a new strategy by quantifying CO2-equivalent (CO2-eq) changes as carbon passes through CWs and tested it in various types of CWs based on 64 literature records. The findings reveal that CWs can contribute to CO2-eq additions, yet are only responsible for 15.6% derived from direct field observations. The type of CWs plays a crucial role in these CO2-eq additions, with vertical flow CWs causing the lowest levels (6.8%), followed by surface flow CWs (14.2%). In contrast, horizontal flow CWs are associated with the strongest CO2-eq addition (25.7%). The findings provide new insights for the objective assessment of the greenhouse effect of biogenic carbon emissions in CWs, which will be beneficial for future life cycle assessment.

Analysis of long-term spatio-temporal changes of plateau urban wetland reveals the response mechanisms of climate and human activities: A case study from Dianchi Lake Basin 1993-2020

Wetlands serve many functions, including conserving water, providing habitats for animals and plants, and regulating climate change. Their unique ecological effects on the natural environment are indispensable in the whole ecosystem. Dianchi Lake Basin is located in Yunnan-Guizhou Plateau, China, and mainly in Kunming. It is a typical plateau urban wetland area. Based on spatio-temporal hotspot mining, spatio-temporal geographically weighted regression, and adaptive multidimensional grey prediction, we conducted correlation analyses of the wetland changes in Dianchi Lake Basin from 1993 to 2020 under the influence of human activities and natural conditions. The results show that (1) the active wetland change zone in Dianchi Lake Basin is mainly located around Dianchi Lake, and (2) the wetlands in some areas on the north and south of Dianchi Lake declined in the early 21st century, but under the protection policy in recent years, the wetlands in these areas gradually recovered. Meanwhile, the wetlands in most areas around Dianchi Lake showed a significant growth trend from 2018 to 2020. The results suggest that the wetland change in Dianchi Lake Basin is mainly related to the urbanization of Kunming, and it can be divided into five regions (strong negative correlation, weak negative correlation, weak correlation, weak positive correlation, and strong positive correlation) according to the different correlation of human activity intensity, among which the main factors affected by nature are different, but they are all related to temperature. This study shows that, although wetlands in plateau cities can be properly restored under proper protection, wetland protection should be kept in step with the development of plateau cities to support sustainable urban development and carbon neutrality.

Spatiotemporal analysis of transition probabilities of wet and dry days under SSPs scenarios in the semi-arid Susurluk Basin, Türkiye

Precipitation, especially in regions dominated by the Mediterranean climate, is one of the most critical parameters of the hydrological cycle and the environment affected by climate change. One the one hand, the transition probabilities of wet and dry days in precipitation occurrence are a relatively new topic, on the other hand these are essential in defining the regional climate. For the first time, spatiotemporal variations of transition probabilities of wet and dry days in the Susurluk Basin, northwestern Türkiye, dominated by a semi-arid Mediterranean climate and also having a mountain climate, were analyzed based on the observation (1979-2014) and future terms (2030-2059 as short and 2070-2099 as long), under four Shared Socioeconomic Pathways (SSPs) scenarios. To do this, statistical downscaling was performed for 14 general circulation models (GCMs) from the CMIP6. By applying an ensemble of four high-performing GCMs, four indices for transition probabilities of wet and dry, i.e., a dry day following a dry day (FDD), a wet day following a dry day (FDW), a dry day following a wet day (FWD), and a wet day following a wet day (FWW), were calculated, and their changes were determined statistically. Monotonic and partial trends of the indices were also analyzed. According to the results, the FDD will increase in water year and wet period and autumn in the future, especially for the long term, in the basin dominated by the FDD (75 % in water year). The risks are higher in the western part of the basin, where human activities are intense, as the FDD is higher in this part than other parts especially in summer (90-100 %) in SSP3-7.0 and SSP5-8.5 scenarios for the long term. So, the length of consecutive dry days in the wet period and water year will increase in the basin, thus increasing the likelihood of droughts. As for the intra-term trends, the FDD increases and the FWW decreases in the water year and seasons in SSP3-7.0 and SSP5-8.5, contrary to the observation term.

Climate Change Will Impact Surface Water Extents and Dynamics Across the Central United States

Climate change is projected to impact river, lake, and wetland hydrology, with global implications for the condition and productivity of aquatic ecosystems. We integrated Sentinel-1 and Sentinel-2 based algorithms to track monthly surface water extent (2017-2021) for 32 sites across the central United States (U.S.). Median surface water extent was highly variable across sites, ranging from 3.9% to 45.1% of a site. To account for landscape-based differences (e.g., water storage capacity, land use) in the response of surface water extents to meteorological conditions, individual statistical models were developed for each site. Future changes to climate were defined as the difference between 2006-2025 and 2061-2080 using MACA-CMIP5 (MACAv2-METDATA) Global Circulation Models. Time series of climate change adjusted surface water extents were projected. Annually, 19 of the 32 sites under RCP4.5 and 22 of the 32 sites under RCP8.5 were projected to show an average decline in surface water extent, with drying most consistent across the southeast central, southwest central, and midwest central U.S. Projected declines under surface water dry conditions at these sites suggest greater impacts of drought events are likely in the future. Projected changes were seasonally variable, with the greatest decline in surface water extent expected in summer and fall seasons. In contrast, many north central sites showed a projected increase in surface water in most seasons, relative to the 2017-2021 period, likely attributable to projected increases in winter and spring precipitation exceeding increases in projected temperature.

Opposite response of constructed wetland performance in nitrogen and phosphorus removal to short and long terms of operation

Constructed wetlands (CWs) have been widely used for treating polluted water since the 1950s, with applications in over 50 countries worldwide. Most studies investigating the pollutant removal efficiency of these wetlands have focused on differences among wetland designs, operation strategies, and environmental conditions. However, there still remains a gap in understanding the variation in wetland pollutant removal efficiency over different time scales. Therefore, the main aim of the study is to address this gap by conducting a global meta-analysis to estimate the variation in nitrogen (N) and phosphorus (P) removal by wetland in short- and long-term pollutant treatment. The findings of this study indicated that the total efficiencies of N and P removal increased during short-term wetland operation but decreased during long-term operation. However, for surface flow CWs specifically, the efficiencies of N and P removal increased during short-term operation and remained stable during long-term operation. Moreover, the study discovered that wetland N removal efficiency was influenced by seasons, with an increase in spring and summer and a decrease in autumn and winter. Conversely, there was no significant seasonal effect on P removal efficiency. Additionally, high hydraulic load impaired wetland N and P removal efficiency during long-term operation. This study offers a critical review of the role of wetlands in wastewater treatment and provides valuable reference data for the design and selection of CWs types during wastewater treatment in the aspect of sustainability.

Monitoring of wetland turbidity using multi-temporal Landsat-8 and Landsat-9 satellite imagery in the Bisalpur wetland, Rajasthan, India

Satellite imagery has emerged as the predominant method for performing spatial and temporal water quality analyses on a global scale. This study employs remote sensing techniques to monitor the water quality of the Bisalpur wetland during both the pre and post-monsoon seasons in 2013 and 2022. The study aims to investigate the prospective use of Landsat-8 (L8) and Landsat-9 (L9) data acquired from the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) for the temporal monitoring of turbidity. Concurrently, the study examines the relationship of turbidity with water surface temperature (WST) and chlorophyll-a (Chl-a) concentrations. We utilized visible and near-infrared (NIR) bands to conduct a single-band spectral response analysis of wetland turbidity. The results reveal a notable increase in turbidity concentration in May 2022, as this timeframe recorded the highest reflectance (0.28) in the NIR band. Additionally, the normalized difference turbidity index (NDTI) formula was used to assess the overall turbidity levels in the wetland. The results indicated that the highest concentration was observed in May 2013, with a value of 0.37, while the second-highest concentration was recorded in May 2022, with a value of 0.25. The WST was calculated using thermal band-10 in conjunction with Chlorophyll-a, utilizing the normalized difference chlorophyll index (NDCI). The regression analysis shows a positive correlation between turbidity and WST, as indicated by R2 values of 0.41 in May 2013 and 0.40 in May 2022. Furthermore, a robust positive relationship exists between turbidity and Chl-a, with a high R2 value of 0.71 in May 2022. These findings emphasize the efficacy of the L8 and L9 datasets for conducting temporal analyses of wetland turbidity, WST, and Chl-a. Additionally, this research underscores the critical role of satellite imagery in assessing and managing water quality, particularly in situations where in-situ data is lacking.

Use of CMIP6 scenarios as a reference to understand the responses of macrophyte germination and seedling growth to future warming and allelopathy co-stressors

The application of appropriate references such as CMIP6 climate scenarios for benchmarking studies of climate change on ecosystems can promote consistency among different climate change research. However, the use of CMIP6 climate scenarios is not common among experiments on the effects of climate change on freshwater ecosystems. Also, little is known about the impact of ecological factor such as allelopathy of alien species on macrophyte germination and seedling growth under different climate scenarios. In our study, by simulating three annual mean temperature changes at global warming levels of 1.5 °C (low warming scenario), 2 °C (medium warming scenario) and 4 °C (high warming scenario) corresponding to CMIP6 multi-model mean change at the corresponding global warming level, we conducted a mesocosm experiment to investigate their possible effects of different climate scenarios and allelopathy co-stressors on macrophyte germination and seedling growth. Our study showed that three warming scenarios all can facilitate macrophyte propagule germination and seedling growth, but the effect paths vary with CMIP6 warming scenarios and there are more influence pathways under high warming scenarios than under low and medium warming scenarios. Higher aqueous extract concentrations of Eichhornia crassipes can significantly stimulate macrophyte propagule germination and seedling growth. And the medium and high warming scenarios may exacerbate the impacts of allelopathic substances on macrophyte germination and seedling growth, and their effects depend on the combination of the two stressors. These results indicated that medium- and high-temperature scenarios may have greater ecological effects on macrophytes than low-temperature scenarios. Thus, our results highlighted that future climate studies need proper benchmarks such as CMIP6 warming scenarios, because it can provide relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supportive coordination among researchers.

A meta-analysis highlights globally widespread potassium limitation in terrestrial ecosystems

Potassium (K+ ) is the most abundant inorganic cation in plant cells, playing a critical role in various plant functions. However, the impacts of K on natural terrestrial ecosystems have been less studied compared with nitrogen (N) and phosphorus (P). Here, we present a global meta-analysis aimed at quantifying the response of aboveground production to K addition. This analysis is based on 144 field K fertilization experiments. We also investigate the influences of climate, soil properties, ecosystem types, and fertilizer regimes on the responses of aboveground production. We find that: K addition significantly increases aboveground production by 12.3% (95% CI: 7.4-17.5%), suggesting a widespread occurrence of K limitation across terrestrial ecosystems; K limitation is more prominent in regions with humid climates, acidic soils, or weathered soils; the effect size of K addition varies among climate zones/regions, and is influenced by multiple factors; and previous N : K and K : P thresholds utilized to detect K limitation in wetlands cannot be applied to other biomes. Our findings emphasize the role of K in limiting terrestrial productivity, which should be integrated into future terrestrial ecosystems models.

Exploring Dynamics of Water, Energy, and Food Systems in Agricultural Landscapes Using Mental Modeling: A Case of Varamin Plain, Iran

This study applies the mental model and cognitive mapping method to involve stakeholders in delineating the mutual relations between sources of water, energy, and food (WEF) production in the Varamin Plain (VP). Through involving farmers and managerial experts, the approach facilitates the deployment of community communication patterns to recognize and comprehend problems and move from single-loop learning to double-loop learning. The dynamic model was driven from the final mental model of the participants to reflect changes in the systems over time. The system dynamic (SD) model incorporates three scenarios for enhancing irrigation efficiency, managing groundwater extraction, and satisfying environmental needs. The results uncovered that the surface and underground water resources of the VP will gradually decrease within the next two decades in the range of 158 and 2700 million cubic meters (MCM) per year. Also, the plain suffers from water insecurity and a 162 MCM shortage. Consequently, focusing on understanding the nexus and nexus governance can enhance resource management and achieve sustainable development goals. Essentially, promoting collaborative governance, such as creating cooperative organizations and implementing double-loop learning, and instituting a water market, regulatory governance, and monitoring laws can improve the state of Varamin Plain's resources. These results carry important policy implications for using mental models to consider dynamics for discussions on participatory management of the WEF system nexus and environmental management.

Review: Research progress on seasonal succession of phyllosphere microorganisms

Phyllosphere microorganisms have recently attracted the attention of scientists studying plant microbiomes. The origin, diversity, functions, and interactions of phyllosphere microorganisms have been extensively explored. Many experiments have demonstrated seasonal cycles of phyllosphere microbes. However, a comprehensive comparison of these separate investigations to characterize seasonal trends in phyllosphere microbes of woody and herbaceous plants has not been conducted. In this review, we explored the dynamic changes of phyllosphere microorganisms in woody and non-woody plants with the passage of the season, sought to find the driving factors, summarized these texts, and thought about future research trends regarding the application of phyllosphere microorganisms in agricultural production. Seasonal trends in phyllosphere microorganisms of herbaceous and woody plants have similarities and differences, but extensive experimental validation is needed. Climate, insects, hosts, microbial interactions, and anthropogenic activities are the diverse factors that influence seasonal variation in phyllosphere microorganisms.

Greenhouse gas emissions from constructed wetlands: A bibliometric analysis and mini-review

Constructed wetlands (CWs) have been widely applied in wastewater treatment; however, the degradation of organic pollutants within CWs leads to substantial emissions of greenhouse gases (GHGs), such as carbon dioxide, methane and nitrous oxide. Under the low-carbon economy, GHG emissions have emerged as a major concern, and have been intensively studied in the CW field. In this study, we conducted a bibliometric review using CiteSpace and a global-scale analysis of GHG emission levels based on 286 records and proposed potential approaches for the future control of GHG emissions in CWs. We found that the research has generally evolved through three stages over the past 15 years: GHG emission level assessment (2007-2010), mechanisms (2011-2016), and control (2017-2022). The type of CWs is closely related to GHG emissions, with free water surface CWs emitting higher levels of methane and vertical subsurface flow CWs emitting higher levels of carbon dioxide and nitrous oxide. By optimizing CW operation, it is conceivable to synergistically reduce GHG emissions while enhancing pollutant removal.

Revealing viral diversity in the Napahai plateau wetland based on metagenomics

We focused on exploring the diversity of viruses in the Napahai plateau wetland, a unique ecosystem located in Yunnan, China. While viruses in marine environments have been extensively studied for their influence on microbial metabolism and biogeochemical cycles, little is known about their composition and function in plateau wetlands. Metagenomic analysis was employed to investigate the viral diversity and biogeochemical impacts in the Napahai wetland. It revealed that the Caudoviricetes and Malgrandaviricetes class level was the most abundant viral category based on phylogenetic analysis. Additionally, a gene-sharing network highlighted the presence of numerous unexplored viruses and demonstrated their unique characteristics and significant variation within the viral community of the Napahai wetland. Furthermore, the study identified the auxiliary metabolic genes (AMGs). AMGs provide phages with additional functions, such as protection against host degradation and involvement in metabolic pathways, such as the pentose phosphate pathway and DNA biosynthesis. The viruses in the Napahai wetland were found to influence carbon, nitrogen, sulfur, and amino acid metabolism, indirectly contributing to biogeochemical cycling through these AMGs. Overall, the research sheds light on the diverse and unique viral communities in the Napahai plateau wetland and emphasizes the significant roles of viruses in microbial ecology. The findings contribute to a deeper understanding of the characteristics and ecological functions of viral communities in plateau wetland ecosystems.

Nanoenabled Enhancement of Plant Tolerance to Heat and Drought Stress on Molecular Response

Global warming has posed significant pressure on agricultural productivity. The resulting abiotic stresses from high temperatures and drought have become serious threats to plants and subsequent global food security. Applying nanomaterials in agriculture can balance the plant's oxidant level and can also regulate phytohormone levels and thus maintain normal plant growth under heat and drought stresses. Nanomaterials can activate and regulate specific stress-related genes, which in turn increase the activity of heat shock protein and aquaporin to enable plants' resistance against abiotic stresses. This review aims to provide a current understanding of nanotechnology-enhanced plant tolerance to heat and drought stress. Molecular mechanisms are explored to see how nanomaterials can alleviate abiotic stresses on plants. In comparison with organic molecules, nanomaterials offer the advantages of targeted transportation and slow release. These advantages help the nanomaterials in mitigating drought and heat stress in plants.