Natural Wetlands Research Articles

Biodiversity during Pre and Post Hula Valley (Israel) Drainage

The natural ecosystem of the Hula Valley (Israel) comprising shallow old lake Hula, swamps and partly cultivated land was altered by drainage. The drained area was converted for agricultural development. The natural wetland–lake ecosystem was demolished. A reduction in biodiversity and a negative impact on the downstream Lake Kinneret water quality were predicted. Forty years later, a reclamation project was implemented aimed at renovation of the hydrological conditions, and agricultural development was improved. The recorded inventory of plants, birds and fish pre- and post-drainage and reclamation was comparatively evaluated resulting in an indication of Biodiversity Index (BDI) and Species Richness (SR) enhancement in the present. It is suggested that the resulting increase in ecological habitat varieties suitable for terrestrial, semi-aquatic and aquatic organisms enhanced the biodiversity. Nevertheless, it is not impossible that the newly created conditions which enhanced the biodiversity require a risk assessment to ensure the long-term sustainability of the integration of agriculture and nature.

Natural way of treatment of domestic waste water by using anaerobic unit and engineered wetlands with phytoremediation

Population of world increase day by day and it may raise more than 9 billion upto 2040. Fresh potable water for drinking, domestic and agricultural use is life line of human, animals, plants. In present situation most of the countries fight with this scarcity of potable water. And in future situation will be very tuff. Construction of engineered wetlands is concept based on natural wetlands. Now days reduction of natural wetlands cause of water pollution, soil pollution and reduction of bio diversity. Processes of engineered wetlands surpass the problems of natural wetlands and will increase the capacity of waste water treatment process. Constructed wetland treated waste water on basis of natural process which is completely non-hazardous, eco-friendly and non-consumption of energy. At in present condition, land is costlier and most of the wetlands vanish due to effective use of lands, hence we found various hazardous changes like ground water depletion, increase of greenhouse gases (Methane, CO2), disturbance/vanishing of bio diversity lived into wetlands. Wetlands are also play a major role for flying animals, water animals for food chain and food web. Development of wetland is always cost effective, durable as compare to others conventional waste water treatments and engineered developed waste water treatment plants. Now a day’s, it very necessary to develop the techniques to reduce carbon foot prints and adopts those technology completely based on natural processes. Nature provides the techniques to humans but it need some scientific and engineered way to develop. Engineered developed wetlands have beautified locality/area and without any kind of odour, smell, nuisance of flying kits etc. Wetlands with pollution absorbent plants create bio diversity and beautified locality.

Identification of bird conservation gaps of protected areas in high-intensity development area: A case study of Tianjin, China.

Due to the long-term disturbance of human activities, natural habitats in the high-intensity development areas have been seriously degraded, causing serious threat to local biodiversity. The conservation efficiency of natural reserves in these regions needs to be improved urgently. Scientific evaluation of conservation efficiency of nature reserves and identification of biodiversity conservation hotspots and conservation gaps in high-intensity development areas are of great significance to sustainable development of urbanization. With birds as the indicator group for biodiversity, we used MaxEnt and InVEST models to calculate the hot spots of bird diversity and habitat quality, and compared with current boundaries of protected areas in Tianjin to accurately identify the conservation gaps. The results showed that 228 bird species belonging to 54 families and 19 orders were recorded. All kinds of natural and artificial wetlands in the coastal area were the most suitable habitats for birds, accounting for 66.8% of bird diversity hotspots in Tianjin, and the artificial wetlands of reservoirs and fish ponds had high suitability as bird habitats due to sufficient food sources, which indicated that moderate anthropogenic interference would improve species diversity. The coverage rate of protected areas for bird diversity hotspots was only 37.7% in Tianjin, which indicated a serious conservation gap. The gaps mainly included wetlands in Dashentang and Lin'gang areas, the river junction and the estuary wetland, which should be planned as the key protected areas in the future. The method of collaborative analysis of the two models could improve the identification accuracy in detecting the conservation gaps and has certain universality for improving the efficiency of biodiversity conservation in high-intensity development areas.

Research on Art Design of Urban Wetland Park Planning Based on the Concept of Sustainable Development

Abstract With the development of the social economy, the scale of cities has expanded rapidly, and the urban ecological imbalance has become increasingly severe, which has caused many urban problems. People gradually realise that cities and human beings develop more harmoniously and healthily by building and developing cities on the basis of natural ecology and seeking the harmonious coexistence of ecology and humanity. The results of the sustainable landscape ecological evaluation of Anhui Shilonghu National Wetland Park show that the park has good ecological, social, and economic benefits and functions. The urban ecological environment and social and economic development have a good supporting effect on the park, and its overall evaluation grade is good. Compared with other waterscape parks, the ecological function of urban wetland parks is the most basic and essential function of the landscape. It has multiple functions, such as popular science education and being close to nature and entertainment. Developing wetland ecological experience tourism activities benefits wetland protection and ecologically coordinated, sustainable development. It can also comprehensively improve wetland parks’ ecological, social, and economic benefits.

The Changes in Dominant Driving Factors in the Evolution Process of Wetland in the Yellow River Delta during 2015–2022

Most of the previous studies exploring the changing patterns of wetland in the Yellow River Delta (YRD) were conducted based on sparse time-series images, which ignored its severe environmental gradient and rapid evolution process of the wetland. The changes in the dominant factors in the evolution of the wetland in the YRD are not clear. This study used the dense time-series Sentinel-2 images to establish a wetland database of the YRD, and then analyzed the spatial distribution characteristics of, and temporal changes in, the wetland during 2015–2022. Finally, the dominant factors of the spatio-temporal evolutions of the wetland were explored and revealed. The results showed the following. (1) During 2015–2022, the wetland in the YRD was dominated by artificial wetland, accounting for 54.02% of the total wetland area in the study area. In 2015–2022, the total wetland area increased by 309.90 km2, including an increase of 222.63 km2 in natural wetlands and 87.27 km2 in artificial wetlands. In the conversion between wetland types, 218.73 km2 of artificial wetlands were converted into natural wetlands, and 75.18 km2 of natural wetlands were converted into artificial wetlands. The patch density of rivers, swamps, and salt pans increased, showing a trend of fragmentation. However, the overall degree of landscape fragmentation in wetlands weakened. The trend of changes in the number of patches and landscape shape index was the same, while the trend of changes in Shannon’s diversity index and Contagion index was completely opposite. (2) Natural factors, such as precipitation (0.51, 2015; 0.65, 2016), DEM (0.57, 2017; 0.47, 2018; 0.49, 2020; 0.46, 2021), vegetation coverage (0.59, 2019), and temperature (0.48, 2022), were the dominant influencing factors of wetland changes in the YRD. The dominant single factor causing the changes in artificial wetlands was vegetation coverage, while socio-economic factors had lower explanatory power, with the average q value of 0.18. (3) During 2015–2022, the interactions between the natural and artificial factors of the wetland changes were mostly nonlinear and showed double-factor enhancement. The interactions between temperature and sunshine hours had the largest explanatory power for natural wetland change, while interactions between precipitation and vegetation coverage, and between temperature and vegetation coverage, had large contribution rates for artificial wetland change. The interactions among natural factors had the greatest impacts on wetland change, followed by interactions between natural factors and socio-economic factors, while interactions among socio-economic factors had more slight impacts on wetland change. The results can provide a scientific basis for regional wetland protection and management.

The Importance of Spatial Resolution in the Modeling of Methane Emissions from Natural Wetlands

An important uncertainty in the modeling of methane (CH4) emissions from natural wetlands is the wetland area. It is difficult to model wetlands’ CH4 emissions because of several factors, including its spatial heterogeneity on a large range of scales. In this study, we investigate the impact of model resolution on the simulated wetland methane emission for the Fennoscandinavian Peninsula. This is carried out using a high-resolution wetland map (100 × 100 m2) and soil carbon map (250 × 250 m2) in combination with a highly simplified CH4 emission model that is coarsened in five steps from 0.005° to 1°. We find a strong relation between wetland emissions and resolution, which is sensitive, however, to the sub-grid treatment of the wetland fraction. In our setup, soil carbon and soil moisture are positively correlated at a high resolution, with the wetland location leading to increasing CH4 emissions with increasing resolution. Keeping track of the wetland fraction reduces the impact of resolution. However, uncertainties in CH4 emissions remain high because of the large uncertainty in the representation of wetland the area, as demonstrated using the output of the WetChimp intercomparison over our study domain. Because of wetland mapping uncertainties, existing models are unlikely to realistically represent the correlation between soil moisture and soil carbon availability. The correlation is positive in our simplified model but may be different in more complex models depending on their method of representing substrate availability. Therefore, depending on the correlation, CH4 emissions may be over- or underestimated. As increasing the model resolution is an effective approach to mitigate the problem of accounting for the correlation between soil moisture and soil carbon and to improve the accuracy of models, the main message of this study is that increasing the resolution of global wetland models, and especially the input datasets that are used, should receive high priority.

Growth and survival of native wetland species in shallow capped centrifuged tailings and co-mixed tailings: a meso-scale greenhouse study

This 3-year meso-scale greenhouse study used 55-gallon columns to evaluate the survival and growth of boreal wetland communities planted on centrifuge (CF) tailings and co-mixed (CM) tailings capped with different reclamation cover soil capping designs. The CF tailings were capped with a shallow layer (10 and 30 cm) of peat reclamation material (PRM) and the CM tailings were capped with a shallow layer (5 cm) of PRM above 15 or 35 cm of reclamation subsoil (till). After 3 years, plant survival and growth on CF tailings showed significant improvement with a 10 cm PRM cap compared to the uncapped tailings, and plants growing on a 30 cm PRM cap outperformed those on the 10 cm PRM cap. Plant growth on CM tailings was significantly improved with a soil cover containing 5 cm PRM and at least 15 cm till. Among the seven native wetland species included in this study, the top performing species in terms of survival and above-ground biomass were Salix bebbiana, Scirpus microcarpus, and Carex aquatilis.

Influence of seasonal variation to the population growth and ecophysiology of Typha domingensis (Typhaceae).

Precipitation is an important climatic element that defines the hydrological regime, and its seasonal variation produces annual dry and wet periods in some areas. This seasonality changes wetland environments and leverages the growth dynamics of macrophytes present, including Typha domingensis Pers. This study aimed to evaluate the influence of seasonal variation on the growth, anatomy and ecophysiology of T. domingensis in a natural wetland. Biometric, anatomical and ecophysiological traits of T. domingensis were evaluated over one year at four-month intervals. Reductions in photosynthesis were evidenced at the end of the wet periods and during the dry periods, and these reductions were associated with thinner palisade parenchymas. Increased stomatal indexes and densities as well as thinner epidermis observed at the beginning dry periods can be associated with higher transpiration rates during this period. The plants maintained their water contents during the dry periods, which may be related to the storage of water in leaf trabecular parenchyma, as this is the first time that results indicate the function of this tissue as a seasonal aquiferous parenchyma. In addition, increasing proportions of aerenchymas were evident during the wet periods, which may be related to a compensation mechanism for soil waterlogging. Therefore, the growth, anatomy and ecophysiology of T. domingensis plants change throughout the year to adjust to both the dry and wet periods, providing conditions for the survival of the plants and modulating population growth.

Coupled anaerobic methane oxidation and metal reduction in soil under elevated CO2.

Continued current emissions of carbon dioxide (CO2 ) and methane (CH4 ) by human activities will increase global atmospheric CO2 and CH4 concentrations and surface temperature significantly. Fields of paddy rice, the most important form of anthropogenic wetlands, account for about 9% of anthropogenic sources of CH4 . Elevated atmospheric CO2 may enhance CH4 production in rice paddies, potentially reinforcing the increase in atmospheric CH4 . However, what is not known is whether and how elevated CO2 influences CH4 consumption under anoxic soil conditions in rice paddies, as the net emission of CH4 is a balance of methanogenesis and methanotrophy. In this study, we used a long-term free-air CO2 enrichment experiment to examine the impact of elevated CO2 on the transformation of CH4 in a paddy rice agroecosystem. We demonstrate that elevated CO2 substantially increased anaerobic oxidation of methane (AOM) coupled to manganese and/or iron oxides reduction in the calcareous paddy soil. We further show that elevated CO2 may stimulate the growth and metabolism of Candidatus Methanoperedens nitroreducens, which is actively involved in catalyzing AOM when coupled to metal reduction, mainly through enhancing the availability of soil CH4 . These findings suggest that a thorough evaluation of climate-carbon cycle feedbacks may need to consider the coupling of methane and metal cycles in natural and agricultural wetlands under future climate change scenarios.

Tracking economic-driven coastal wetland change along the East China Sea

Coastal wetlands provide various ecological functions but are threatened by land reclamation and urbanization, which cause wetland degradation and loss. Understanding wetland transition trends and driving factors is challenging. Here, we used the Environmental Kuznets curve (EKC) to analyze the relationship between coastal wetlands, as classified by the Google Earth Engine (GEE), and socio-economic indicators along the East China Sea. Structural equation modeling (SEM) was used to explore the driving factors. We found that the (1) wetland transition depended on geomorphic units and socio-economic development; (2) wetland area changes from 1985 to 2020 had a typical EKC pattern and can be divided into three periods due to policy changes; and (3) economic development and urbanization were the primary reasons for wetland changes, with a strong correlation between natural wetland area, GDP per capita, and impervious surface, but a lower correlation with aquacultural area.

Peruvian Wetlands: National Survey, Diagnosis, and Further Steps toward Their Protection

Wetlands are crucial hydrological features that provide benefits, including ecosystem services and habitat conservation, protection from flooding associated with sea level rise and extreme events, water storage and treatment, recreation, and aesthetics, among others. Peru is one of the few countries in Latin America that has not developed a national wetland inventory. While this can in part be attributed to the limited availability of peer-reviewed publications in the English literature, a larger quantity of Peruvian wetland-related publications are available in Spanish, and are less accessible to the global population. In this paper, we developed an extensive review and synthesis of the Spanish literature, including university theses, peer-reviewed articles, and government reports. Our report focuses on evaluating the state of the art of Peruvian wetlands in terms of temporal evolution, geographical distribution, vested institutions, research topics (e.g., water quality, fauna, flora, microorganisms, etc.), and advances toward the conservation of wetlands. The analysis identified 274 wetland-related publications in Spanish (188 theses, 83 peer-reviewed, and 6 government reports) and a temporal increase in dissemination over the past two decades. The reports encompassed 161 distinct wetlands distributed nationwide; however, most of the investigations focused on only a few wetland bodies with a disproportionate concentration in just three administrative regions. This reveals that wetland-related research is unevenly distributed in Peru, and highlights a need to extend this knowledge to underrepresented systems and regions. Although Peru ranks third in South America for protected (Ramsar) wetland areas, case studies have revealed that wetlands in the country are vulnerable to human activities. Recent national legislation established in 2021 should help to address this challenge, as before this time, there was a more decentralized approach, whereby each administrative region held responsibility for the protection of their own wetlands. Collective findings indicate that research activity should be increased nationally in order to better understand the function and benefits of wetlands throughout Peru, in addition to the continued development and enforcement of regulations designed to protect these valuable ecosystems. Finally, since a national Peruvian wetland inventory is urgently needed, this analysis provides a baseline for this development of, as well as identifying gaps in, knowledge needed for appropriate national representation.

Biomonitoring trace metal contamination in Guangzhou urban parks using Asian tramp snails (Bradybaena similaris)

Anthropogenic activities have caused environmental metal contamination in urban areas. Biomonitoring using organisms such as invertebrates can evaluate metal pollution, supplementing chemical monitoring, which cannot comprehensively reflect how metals influence organisms in the urban environment. To assess metal contamination in Guangzhou urban parks and its source, Asian tramp snails (Bradybaena similaris) were collected from ten parks in Guangzhou in 2021. The metal concentrations (Al, Cd, Cu, Fe, Mn, Pb, and Zn) were measured by ICP–AES and ICP–MS. We evaluated the metal distribution characteristics and correlations among metals. The probable sources of metals were determined by the positive matrix factorization (PMF) model. The metal pollution levels were analysed using the pollution index and the Nemerow comprehensive pollution index. The mean metal concentrations were ranked Al > Fe > Zn > Cu > Mn > Cd > Pb; metal pollution level in the snails was ranked Al > Mn > CuFe > Cd > Zn > Pb. Pb–Zn–Al–Fe–Mn and Cd–Cu–Zn were positively correlated in all samples. Six major metal sources were identified: an Al–Fe factor corresponding to crustal rock and dust, an Al factor related to Al-containing products, a Pb factor indicative of traffic and industries, a Cu–Zn–Cd factor dominated by the electroplating industry and vehicle sources, an Mn factor reflecting fossil fuel combustion, and a Cd–Zn factor related to agricultural product use. The pollution evaluation suggested heavy Al pollution, moderate Mn pollution, and light Cd, Cu, Fe, Pb, and Zn pollution in the snails. Dafushan Forest Park was heavily polluted; Chentian Garden and Huadu Lake National Wetland Park were not widely contaminated. The results indicated that B. similaris snails can be used as effective biomarkers for monitoring and evaluating environmental metal pollution in megacity urban areas. The findings show that snail biomonitoring provides a valuable understanding of the migration and accumulation pathways of anthropogenic metal pollutants in soil‒plant–snail food chains.

Impacts of land-use change on carbon dynamics in China's coastal wetlands

The impact of land-use and land-cover change (LULCC) on ecosystem carbon (C) dynamics has been previously documented at local and global scales, but uncertainty persists for coastal wetlands due to geographical variability and field data limitations. Field-based assessments of plant and soil C contents and stocks of various LULCC types were conducted in nine regions along the coastline of China (21°–40°N). These regions cover natural coastal wetlands (NWs, including salt marshes and mangroves) and former wetlands converted to different LULCC types, including reclaimed wetlands (RWs), dry farmlands (DFs), paddy fields (PFs) and aquaculture ponds (APs). The results showed that LULCC generally decreased the C contents and stocks of the plant–soil system by 29.6 % ± 2.5 % and 40.4 % ± 9.2 %, respectively, while it slightly increased the soil inorganic C contents and stocks. Wetlands converted to APs and RWs lost greater ecosystem organic C stocks (EOC, sum of plants and top 30 cm of soil organic C stocks) than other LULCC types. The annual potential CO2 emissions estimated from EOC loss depended on the LULCC type, with an average emission of 7.92 ± 2.94 Mg CO2-eq ha−1 yr−1. The change rate of EOC in all LULCC types showed a significantly deceasing trend with increasing latitude (p < 0.05). The loss of EOC due to LULCC was larger in mangroves than in salt marshes. The results showed that the response of plant and soil C variables to LULCC was mainly related to differences in plant biomass, median grain size, soil water content and soil NH4+-N content. This study emphasized the importance of LULCC in triggering C loss in natural coastal wetlands, which strengthens the greenhouse effect. We suggest that the current land-based climate models and climate mitigation policies must account for specific land-use types and their associated land management practices to achieve more effective emission reduction.

Wetland Restoration Dilemma in Uganda: Investigation of Alternative Livelihood Options for Restoring Limoto Wetland in Eastern Uganda

Purpose: Motion 145 adopted by the 5th IUCN World Conservation Congress in 2012, called for an evaluation of alternative livelihood programs' contributions to biodiversity conservation. And since then, alternative livelihood opportunities are employed globally as a way to protect biodiversity, notably for wetlands. This study aims to advance the evaluation of alternative livelihood options' effects on biodiversity. The objective of the study is to describe the effectiveness of alternative livelihood options in the restoration of the Limoto wetland. &#x0D; Methodology: A cross-sectional research design was adopted. Both quantitative and qualitative data were collected using Focus Group Discussions (FGD) and interviews. FGDs were conducted with five groups of beneficiaries of livelihoods options. Interviews were carried out with seven key informants who were considered to be knowledgeable about the wetland restoration alternative livelihood options. These included village local council chairpersons from communities near the wetland, opinion leaders, district natural resources officers, IUCN Representative, NEMA official and wetland department.&#x0D; Findings: The study revealed that the livelihood options initiated for Limoto wetland restoration were ineffective and unsustainable. While, the study further revealed that the wetland restoration program had led to food shortages due to loss of wetland farmland. The study findings showed that re-encroachment was substantially due to a lack of perceived relevance and dissatisfaction with the alternative livelihood options.&#x0D; Unique Contribution to Theory, Practice and Policy: The study concludes that wetland re-encroachment is caused by the beneficiaries’ dissatisfaction of the alternative livelihood options introduced. Therefore, the study recommends the alternative livelihood options be determined using a co-creating design, where the communities are involved and this is in accordance with National Environment Act No.5, 2019 Uganda.&#x0D;

Occurrence dataset of birds in the Xinjizhou National Wetland Park, Nanjing, China.

Xinjizhou National Wetland Park is located in Jiangning District, Nanjing, Jiangsu, China. With diverse wetland landscape types, Xinjizhou National Wetland Park maintains high biodiversity all year around. Meanwhile, as an important hub on the East Asian-Australasian Flyway, Xinjizhou National Wetland Park also occupies a core ecological position in the middle and lower reaches of the Yangtze River in Jiangsu Province. Therefore, carrying out systematic bird surveys and consequently understanding the distribution of birds and the seasonal variation of their communities can provide important insights for conservation. We conducted a one-year bird survey in the Xinjizhou National Wetland Park from 2021 to 2022 and provided occurrence datasets, including detailed species and geographic information.This dataset fills the knowledge gap in avian community composition for the Wetland Park and more importantly provides a basis to assess the conservation effectiveness of conservation measures taken in the Wetland Park. This occurrence dataset is the first public record of birds in Xinjizhou National Wetland Park. All data have been published on GBIF.

Study on the Spatial and Temporal Evolution of the Ecological Environmental Quality in Linghekou Wetland

Coastal wetlands are located in the overland area between land and sea and play an important ecological role, but social and economic development and the acceleration of urbanization have resulted in the degradation of the ecological functions of coastal wetlands and serious pollution within the wetlands. The study of the spatial and temporal changes in the ecological environmental quality of coastal wetlands can suggest feasible response strategies for the ecological construction of coastal wetlands. This study uses RS and GIS technology, based on the PSR model, AHP method and InVEST model, to study the spatial and temporal changes in the ecological environmental quality of the Linghekou wetland and to propose early warning on future ecological and environmental conditions. The results show the following: (1) The natural wetland area decreased, the landscape fragmentation index increased and the wetland landscape showed a degradation trend between 2005 and 2020. (2) The composite indices for the evaluation of the ecological environmental quality of the Linghekou wetland in 2005, 2010, 2015 and 2020 were 0.473, 0.380, 0.353 and 0.378, respectively, with the ecological environmental quality declining from a sub-healthy state in 2005 to a sub-sick state in 2020, with increasing interference from human activities, increasing differentiation of the internal organization of the wetlands and degradation of ecological services. (3) The habitat quality of the Linghekou wetland has improved since 2015 due to the implementation of local conservation measures, but the habitats are still under strong pressure from anthropogenic disturbance. (4) The predicted results for 2025 and 2030 show that the ecological environmental quality of the Linghekou wetland will continue to deteriorate in the future, especially in the northwestern and central-eastern parts of the study area, where anthropogenic disturbance will continue to intensify and habitat degradation will become more severe in the future. This study provides a scientific reference for coastal wetland management and ecological construction, and also enriches the research results on coastal wetlands in the field of ecological and environmental assessment.

Response of methanogenic community and their activity to temperature rise in alpine swamp meadow at different water level of the permafrost wetland on Qinghai-Tibet Plateau.

Wetlands are an important source of atmospheric methane (CH4) and are sensitive to global climate change. Alpine swamp meadows, accounting for ~50% of the natural wetlands on the Qinghai-Tibet Plateau, were considered one of the most important ecosystems. Methanogens are important functional microbes that perform the methane producing process. However, the response of methanogenic community and the main pathways of CH4 production to temperature rise remains unknown in alpine swamp meadow at different water level in permafrost wetlands. In this study, we investigated the response of soil CH4 production and the shift of methanogenic community to temperature rise in the alpine swamp meadow soil samples with different water levels collected from the Qinghai-Tibet Plateau through anaerobic incubation at 5°C, 15°C and 25°C. The results showed that the CH4 contents increased with increasing incubation temperature, and were 5-10 times higher at the high water level sites (GHM1 and GHM2) than that at the low water level site (GHM3). For the high water level sites (GHM1 and GHM2), the change of incubation temperatures had little effect on the methanogenic community structure. Methanotrichaceae (32.44-65.46%), Methanobacteriaceae (19.30-58.86%) and Methanosarcinaceae (3.22-21.24%) were the dominant methanogen groups, with the abundance of Methanotrichaceae and Methanosarcinaceae having a significant positive correlation with CH4 production (p < 0.01). For the low water level site (GHM3), the methanogenic community structure changed greatly at 25°C. The Methanobacteriaceae (59.65-77.33%) was the dominant methanogen group at 5°C and 15°C; In contrast, the Methanosarcinaceae (69.29%) dominated at 25°C, and its abundance showed a significant positive correlation with CH4 production (p < 0.05). Collectively, these findings enhance the understanding of methanogenic community structures and CH4 production in permafrost wetlands with different water levels during the warming process.

Greenhouse gas emissions and environmental drivers in different natural wetland regions of China

Wetlands sequestrate carbon at the highest rate than any other ecosystems on Earth. However, the spatial and temporal dynamics of GHGs emissions from the wetland ecosystems in China are still elusive. We synthesized 166 publications that contain 462 in situ measurements of GHGs emissions from the natural wetlands in China, and further analyzed the variability and the drivers of GHGs emissions in eight subdivisions of China's wetlands. The results show that the current studies are mainly concentrated in the estuaries, Sanjiang Plain, and Zoige wetlands. The average CO2 emissions, CH4 fluxes and N2O fluxes from Chinese wetlands were 218.84 mg·m−2·h−1, 1.95 mg·m−2·h−1 and 5.8 × 10−2 mg·m−2·h−1, respectively. The global warming potential (GWP) of China's wetlands was estimated to be 1881.36 TgCO2-eq·yr−1, with CO2 emissions contributing more than 65% to the GWP value. The combined GWP values of Qinghai-Tibet Plateau wetlands, coastal wetlands and northeastern wetlands account for 84.8% of GWP of China's wetlands. Correlation analysis showed that CO2 emissions increased with the increasing mean annual temperature, elevation, annual rainfall, and wetland water level, but decreased with soil pH. CH4 fluxes increased with the mean annual temperature and soil water content but decreased with the redox potential. This study analyzed the drivers of GHGs emissions from wetland ecosystems at the national scale, and GWP values of eight wetland subregions of China were comprehensively assessed. Our results are potentially useful for the global GHGs inventory, and can help assess the response of GHGs emissions of wetland ecosystem to environmental and climate change.

Spatiotemporal changes of wetlands in China during 2000–2015 using Landsat imagery

China has abundant wetland resources; however, wetland ecosystems are experiencing critical challenges owing to continuous anthropogenic activities and climate change. Therefore, rapid and accurate mapping of wetlands and analysis of the drivers of spatiotemporal changes in wetlands are of great importance for wetland resource conservation. In this study, we proposed a comprehensive method for wetland mapping in China based on Landsat images, in which inland wetlands were identified by the object-oriented and hierarchical classification method, and coastal wetlands were extracted by visual interpretation based on sea boundaries and sea level nodes. Additionally, partial least squares structural equation modelling was utilized to exploit the mechanisms of spatiotemporal variability in wetlands during 2000–2015. The application of the comprehensive method to Landsat TM/OLI resulted in wetland maps of China with overall classification accuracies above 85%. The national wetland maps demonstrated that the wetland areas of China in 2000 and 2015 were 476,305.68 and 456,262.01 km2, respectively, and swamps accounted for the largest proportion of the total wetland area in China (over 38%). Statistics show that wetlands are mainly located in the northern inland areas, such as Tibet, Inner Mongolia, and Xinjiang Autonomous Region, as well as the Qinghai and Heilongjiang Provinces. Wetland changes were concentrated in the Tibetan Plateau, Loess Plateau, Song-Liao Plain, and middle and lower reaches of the Yangtze River. Human activities and climate change were the primary contributors to wetland changes in China. These two factors can not only directly influence wetland changes but also can be indirectly influenced by other factors, such as soil and topography. The results of this study are intended to provide basic data for monitoring and conserving wetland resources in China.

Heterotrophic aquatic metabolism and sustained carbon dioxide emissions in a mineral-soil wetland restored with treated effluent

Wetlands are economically valuable ecosystems, in part because they purify wastewater by retaining and processing nutrients, organic matter (OM), and other pollutants. While natural wetlands are highly productive and sequester large pools of carbon (C), it is unclear whether the C cycle of restored treatment wetlands is functionally consistent with natural systems. This knowledge gap limits our appreciation for the role that wetland restoration can play as a natural solution to climate change. Here, we quantified metabolic and C cycling patterns of a restored, multi-basin wetland (Frank Lake, Alberta, Canada) receiving municipal and beef processing plant effluents rich in nutrients and OM. We conducted metabolic measurements in all three basins using dissolved oxygen sensors deployed under ice and in open water. Extreme production and respiration indicated that effluent was largely mineralized and replaced with wetland OM in transit. The heterotrophic status of all basins aligned with a published mass budget demonstrating the aquatic habitat of the wetland was an OM sink under current drought conditions that lengthen effluent processing time. Floating chamber measurements in open water zones confirmed that the wetland was a source of CO2 to the atmosphere. From input to outflow, sustained emissions led to declining pCO2 and a decline in the ratio of dissolved inorganic to organic C. Over 30 years post-restoration, the open water habitats in Frank Lake remain heterotrophic and a net source of CO2, suggesting that the trajectory of aquatic C cycling may be distinct from wetlands restored with non-effluent water sources.