Greenhouse Gas Fluxes Research Articles

Ecological restoration reduces greenhouse gas emissions by altering planktonic and sedimentary microbial communities in a shallow eutrophic lake.

Ecological restoration reduces greenhouse gas emissions by altering planktonic and sedimentary microbial communities in a shallow eutrophic lake.

Rodent-induced grassland degradation increases annual non-CO2 greenhouse gas fluxes and NO losses despite CH4 uptake enhancement

Rodent-induced grassland degradation increases annual non-CO2 greenhouse gas fluxes and NO losses despite CH4 uptake enhancement

Greenhouse gas flux measurements from agricultural sites within the Swiss FluxNet network

The Swiss FluxNet provides ecosystem scale flux data for the major land use types in Switzerland. While the current station network includes long-term eddy covariance flux measurements from two forest sites (mixed deciduous forest Lägeren and evergreen spruce forest Davos), three permanent grassland sites (Chamau, Früebüel and Alp Weissenstein) as well as three cropland sites (Oensingen, Tänikon and Forel) complement the network. In addition, the measurements cover an altitude gradient ranging from 393 to 1978 m.a.s.l. Carbon dioxide (CO2) and water vapor (H2O) fluxes are measured continuously at all sites, while nitrous oxide (N2O) and methane (CH4) fluxes are also quantified at some sites. Currently, 123 site-years of data are openly shared with FLUXNET. Ancillary meteorological and soil microclimate data are collected continuously as well; plant growth is routinely monitored at all agricultural sites, i.e., grasslands and croplands. Together with the management data, such continuous measurements allow integrated multi-year (Feigenwinter et al. 2023b) and multi-site (Zeeman et al. 2010) comparisons, identification of drivers for greenhouse gas (GHG) fluxes (Maier et al. 2022, Feigenwinter et al. 2023a), quantification of C sequestration (Emmel et al. 2018), as well as assessments of management practices towards sustainable agriculture (Fuchs et al. 2018). Here, we will present long-term CO2 fluxes (since 2004) as well as CH4 and N2O fluxes measured at the six agricultural Swiss FluxNet sites, i.e., three permanent grasslands and three croplands with their typical Swiss crop rotation. Moreover, the contribution of abiotic and biotic drivers to intra- and interseasonal variations in GHG fluxes will be discussed, potential trade-offs among climate mitigation goals identified, and the importance of management information emphasized. We encourage other research teams to use the open-access dataset, growing annually, and seek collaboration in integrated flux measurements worldwide.

Greenhouse gas fluxes in an oxbow lake and its exposed sediments during periods of hydraulic connection and disconnection

After decades of systematic simplification of river ecosystems through hydraulic interventions that have reduced the interactions between the river and its floodplain, projects are now underway to reconnect rivers with riparian areas and lateral canals. The navigation groynes separating the Po River from the Gussola oxbow lake (Cremona, northern Italy) underwent a requalification intervention in March 2023, which consisted of lowering them in order to increase the frequency of flooding and, consequently, the interaction between the river and the oxbow lake. Before and after the requalification, the oxbow lake saturation and fluxes of CO2, CH4 and N2O were measured to analyse the effects of connectivity and rewetting on the sink or source role for greenhouse gases. Other parameters included temperature, conductivity, pH, dissolved oxygen, nutrients and chlorophyll. We hypothesised that the disconnection of the Gussola oxbow lake from the Po River would result in isolated, stagnant ponds prone to algal blooms, reducing CO2 concentrations and fluxes, and bottom hypoxia/anoxia, leading to anaerobic pathways in sediments and the accumulation and evasion of CH4 and N2O. We also hypothesized that evaporation would set to zero CH4 and N2O fluxes to the atmosphere through exposed sediments, but increase those of CO2 due to increased air and oxygen penetration. All greenhouse gas fluxes were carried out on a seasonal basis along 2023 and 2024, and intensified during hydrological extremes. Measurements were made in situ, using portable analysers connected to floating or benthic chambers when fluxes were the target, or to 1 L glass bottles half-filled with in situ water when saturations were the target. The results suggest that when the Gussola oxbow lake is isolated, it rapidly stratifies, the bottom water becomes anoxic and releases large amounts of CH4. Evaporation leads to fragmentation of the oxbow lake into ponds, where algal blooms can be replaced by macrophytes, if hydraulic disconnection persists. Macrophyte meadows, especially those with emergent plants, are CO2 sink hotspots. Floods set to zero primary producer communities, destratify the water column, restore oxic conditions and result in large nutrient and sediment input to the oxbow lake. Floods reduce CH4 saturation and evasion, but large nitrate inputs stimulate denitrification in the oxbow lake and N2O evasion. In exposed sediments, water saturation gradients regulate CO2 and N2O emissions (peaking in unsaturated sediments) and CH4 emissions (peaking in saturated sediments). In the case of sediments, N2O is likely to be released as a consequence of increased nitrification rates. The results of this study shed light on the multiple mechanisms regulating greenhouse gas dynamics, which are activated or deactivated during periods of flooding and hydraulic connectivity, and during period of low discharge and isolation of lateral canals as oxbow lakes.

Restoration of former peat extraction areas is a key measure to enhance biodiversity and mitigate climate change.

The restoration of former peat extraction areas offers an opportunity to integrate nature-based solutions (NbS) into post-extraction land use, enhancing carbon sequestration, biodiversity, and water retention. By rewetting degraded peatlands and implementing NbS-based land-use strategies such as wetland creation and Sphagnum moss re-establishment, these areas can regain essential ecosystem functions while contributing to the EU Green Deal’s climate objectives. However, obtaining sciece-based evidence for the long-term success of these measures requires continuous monitoring to assess their effectiveness in reducing greenhouse gas emissions and improving ecosystem resilience. This study examines how different post-extraction land-use options affect water quality, greenhouse gas emissions, and biodiversity in the former Komppasuo peat extraction area. Baseline measurements were conducted before restoration, and ongoing monitoring tracks the site's recovery into a carbon sink. Key methods include hydrological monitoring, greenhouse gas flux measurements, and standardized vegetation and bird surveys. Active and passive vegetation reintroduction and optimized water level management have been tested to reduce peat decomposition. Drone imagery has been used to monitor spatial changes, providing valuable insights into vegetation development and wetland formation dynamics. Results show that vegetation recovery has progressed rapidly, especially in ash-treated areas, where the pre-treatment has enhanced plant establishment. Wetland habitats have developed diverse ecological conditions, supporting increased species diversity and altering bird community composition. The introduction of water level management structures has facilitated hydrological stabilization, but further adjustments may be needed to optimize conditions for peat-forming vegetation. Initial greenhouse gas data indicate that CO₂ emissions have decreased, but methane fluxes remain variable and require further long-term monitoring to determine net climate effects. Water quality results show that restoration has increased nutrient loading to downstream waters, and after removing peat extraction-related water protection structures, runoff is more nutrient-rich than during peat extraction. These findings underline the importance of site-specific management strategies to minimize unintended environmental impacts while maximizing restoration benefits. Peatland restoration requires balancing multiple, sometimes conflicting, objectives. Hydrological restoration can improve carbon sequestration potential but may temporarily increase methane emissions and nutrient leaching. Long-term monitoring is essential to determine whether degraded peatlands can become carbon sinks and how different land-use strategies influence this process. A critical zone approach is needed in the monitoring framework to fully understand complex interactions between hydrology, soil processes, vegetation dynamics, and greenhouse gas fluxes. Restoring hydrological connectivity is particularly important for ensuring long-term ecosystem recovery and stability.

Carbon and Water Fluxes in a Temperate Scots Pine Chronosequence Study in Poland: An EC Measurement Story from an ICOS-Aspiring Country

Long-term measurements of greenhouse gases, and consequently the carbon, water, and nitrogen cycles, have been the focus of numerous studies for decades. Currently, the most accurate and widely used method for real-time, spatially-averaged estimates of these fluxes is the eddy covariance technique (EC). Over time, individual sites across Europe have been integrated into the Integrated Carbon Observation System (ICOS), creating a network with standardized measurement and data processing protocols, thereby producing high-quality, directly comparable results. Since forests play a major role in the land CO2 sink both globally and in Europe, there is naturally a substantial number of forest EC sites within ICOS. However, there are still well-equipped research sites that, for various reasons, are not yet included in this network. A notable example is Poland, the ninth largest country in Europe by area (and seventh by population), which also marks the eastern border of the European Union. In this presentation, we aim to highlight the most interesting results from a network of Scots pine forest sites in Poland, which have been measuring EC CO2 and H2O fluxes for periods ranging from a few to over 10 years. The primary goal is not only to share the results of our analysis but also to explore new collaboration opportunities with the eLTER network to fully utilize the potential of our sites beyond greenhouse gas fluxes. To provide context for why Scots pine (Pinus sylvestris) was chosen for the Polish network, it is the most widespread pine species globally and the second most distributed conifer after the common juniper (Juniperus communis). Its natural Euro-Asian range spans vast areas, and in Poland, Scots pine dominates 58.6% of the total forest area. Additionally, the mean age of Scots pine trees in Poland is 62 years, meaning that most of them are mature stands. After several years of continuous EC and basic meteorological measurements, complemented by carbon stock inventories in soil and biomass, we addressed the following research questions: What is the nature of the relationship between the age of temperate, managed Scots pine stands, and their sequestration abilities (chronosequence approach)? At what age do these stands reach their maximum sequestration potential? Does the classic forest inventory-based carbon accumulation in woody biomass align with the EC-derived Net Ecosystem Exchange estimates at both annual (based on dendrometers) and multiannual (forest inventory) scales? What is the nature of the relationship between the age of temperate, managed Scots pine stands, and their sequestration abilities (chronosequence approach)? At what age do these stands reach their maximum sequestration potential? Does the classic forest inventory-based carbon accumulation in woody biomass align with the EC-derived Net Ecosystem Exchange estimates at both annual (based on dendrometers) and multiannual (forest inventory) scales? Additional questions related specifically to the impact of different forest management practices on the carbon budget of temperate Scots pine forests were also explored and will be discussed here. In conclusion, although the presented Scots pine EC sites are not yet part of ICOS, the results may be of significant interest to other forest site Principal Investigators (PIs) in this network. This comprehensive, long-term dataset on carbon and water flux exchange between the atmosphere and one of Europe’s most common forest tree species holds relevance not only for climate-related impacts but also for socio-economic factors, as Scots pine is a crucial wood source species.

REWET (REstoration of WETlands to minimise emissions and maximise carbon uptake – a strategy for long-term climate mitigation) – Carbon and methane fluxes at the peatland Ylpässuo in Kiuruvesi, Finland

Ylpässuo is an aapa-mire peatland complex dominated by oligo-mesotrophic Sphagnum fen vegetation, located in the middle boreal zone in the North-Savonia province, Finland. In the past decades, some marginal areas were drained due to forestry activities, changing the carbon pools and possibly triggering the shifting of dominant species, which is little known. Since 2020, Ylpässuo has been protected by the Natural Heritage Foundation with a donation from the University of Eastern Finland, aiming to restore the original watery mire characters. In 2022, Ylpässuo was developed as an open lab under the REWET/EU-Horizon project (2022-2026). To better understand the capacity of carbon sequestration and the impact of species shifting on greenhouse gases at Ylpässuo. In 2023, the eddy covariance monitoring system was successfully established, and greenhouse gas fluxes, including carbon dioxide (CO2) and methane (CH4) fluxes, have been successfully collected since August of 2023. Results from 2024 showed that the eddy covariance system has a good energy closure, and the coefficient of determination between energy in and out was 0.92 (Fig. 1), indicating the good quality of carbon flux measurements at Ylpässuo (Mauder et al. 2024). Moreover, variations of CO2 fluxes show that the maximum gross primary productivity (GPP) and ecosystem respiration (Reco) occurred in the middle of June, whereas the minimum net ecosystem exchange (NEE) occurred in the mid of July (Fig. 2). In the beginning of May, when the long winter finished and snow was melted, CH4 flux was already active as a source until the end of the growing season (September) (Fig. 2). In conclusion, our preliminary results indicate that Ylpässu was a CO2 sink and CH4 source. However, overall, the carbon released as methane can still be offset by wet peatlands acting as carbon sinks, highlighting the importance of peatland restoration to mitigate climate warming. The impact of species composition and species shift on greenhouse gas emissions needs long-term continuous monitoring.

Long-term effects of drought and rewetting manipulations on the greenhouse gas balance of a temperate forest soil.

Climate change is increasing the frequency and intensity of extreme weather events such as drought and episodic heavy rainfall events in large areas of the world, including Central Europe. These disturbances affect fundamental biogeochemical processes and alter greenhouse gas fluxes in forest soils. In this framework, we operate an in-situ lab to investigate long-term effects on forest soils due to altered precipitation patterns. At Lehrforst Rosalia, an eLTER site, we have been performing active manipulations since 2013, involving different frequencies and intensities of drought and rewetting cycles. Since 2020, we have expanded the experiment to include increased atmospheric N-deposition. Soil greenhouse gas fluxes (CO2, CH4 , N2O) are measured at high temporal resolution, together with soil moisture and temperature. Furthermore, periodic soil sampling campaigns are conducted to explore dynamics of soil chemical and microbiological properties. Our long-term data shows that increased frequency and intensity of drought and rewetting results in a reduction of soil respiration rates together with an increase in soil CH4 uptake. This pattern is associated with both altered water dynamics and changes in soil microbial communities. Overall, our results clearly show that the effects of drought dominate the effects of rewetting. The data we generate at Lehrforst Rosalia are critical for understanding how ecosystems react to environmental stressors and feed process-based models to develop further scenarios.

Comparing greenhouse gas dynamics and soil conditions in a newly restored wetland and a long-established natural site

Wetland restoration often aims to re-establish native vegetation and improve ecosystem functions, including greenhouse gas (GHG) regulation and biodiversity support. This study compares a newly restored spruce plantation, where managed vegetation was recently removed to encourage the return of native species, with a control site restored over a decade earlier, where natural vegetation and ecosystem functions have achieved greater stability. The objective was to assess how restoration stages influence GHG fluxes and associated soil conditions. Over one year, methane (CH4) and carbon dioxide (CO2) fluxes were measured bi-weekly using closed chambers with a LI-7810 trace gas analyzer (LICOR Biosciences). Sampling focused on five key zones: three sections within the newly restored site (one near a water channel (NS), an area adjacent to a closed ditch (NCD), and an area far from the ditch (FDC)), one partly dominated by old-native vegetation (Wood), and a mature, naturally vegetated control site (Control). GHG measurement results revealed significant variations among the sampling sites. The control site showed the lowest CH4 emissions, ranging from -3.62 to 0.47 nmol CH4 m⁻² s⁻¹, and Reco ranging from 0.05 to 3.93 µmol CO2 m⁻² s⁻¹. In contrast, the unrestored site with old vegetation and the newly restored site showed greater variability, with CH4 fluxes ranging from -0.68 to above 84.88 nmol CH4 m⁻² s⁻¹, while Reco ranged from 0.01 to above 28.49 µmol CO2 m⁻² s⁻¹. Additionally, soil parameters, including pore water electrical conductivity, temperature, moisture content, and soil carbon (C%) and nitrogen (N%) concentrations, were measured at each sampling site. The control site showed the highest soil nutrient levels (C% = 12.7, N% = 0.73), indicating greater organic matter accumulation. By contrast, the other sites showed lower and variable nutrient levels, with C% ranging from 3.7 to 10.5% and N% from 0.21 to 0.61%. Other measured parameters also varied significantly across the sampling sites. These findings highlight the significant impact of restoration stages on GHG dynamics and soil properties. The control site, with its mature vegetation, represents a stable ecosystem. Meanwhile, the newly restored areas are characterized by higher GHG emissions and variable soil parameters, likely driven by ongoing ecological transitions. This study provides valuable insights into the processes that guide ecosystem recovery by comparing an established ecosystem to a site in the early stages of restoration. The results can inform future restoration strategies to enhance wetland functionality, improve biodiversity, and support climate regulation.

Are natural mires warming or cooling Earth’s climate? - A perspective by the new ACME metric

Introduction Mire ecosystems, i.e. peat forming wetlands, have sequestered carbon dioxide (CO2) from the atmosphere for millenia accumulating its carbon (C) into thick peat deposits. This has created a negative perturbation to the atmospheric CO2 content with a consequent climate cooling effect. At the same time, the mires emit methane (CH4) into the atmosphere, which results in a climate warming effect as CH4 is a powerful greenhouse gas (GHG). Thus, the functioning of mire ecosystems involves GHG fluxes with opposing effects on Earth’s radiative balance (e.g. Frolking et al. (2006)). Commensuration of the radiative forcing (RF) of different GHGs is crucial for understanding the effects of land cover and ecosystem changes on the global climate. However, none of the current commensuration approaches, such as those based on the Global Warming Potential (GWP) or Sustained GWP values, are suitable for addressing the current climatic effect of natural mire ecosystems. Here, our aim has been to develop a practical method to correctly quantify the climatic effect of natural mire ecosystems as compared to a situation in which such a mire ecosystem would not exist. Materials and Methods The radiative forcing due to a perturbation to the atmospheric mixing ratio of a well-mixed GHG depends on the magnitude of the perturbation and the radiative efficiency of the GHG in question. The temporal dynamics of the atmospheric GHG content can be modelled by integrating an atmospheric impulse-response function (Enting 2003). For CH4 and nitrous oxide (N2O), we adopted first-order decay functions (Myhre et al. 2013). For CO2, the dynamics are more complex, and the processes acting in widely differing time scales were modelled by dividing the total CO2 mass into several compartments. One of these has a very long perturbation time scale, thus resulting in a permanent change in the atmospheric CO2 content, while in the others an atmospheric mass pulse decays with a characteristic, finite time scale (Joos et al. 2013). The radiative efficiencies were derived from the RF parameterization of Etminan et al. (2016). As discussed earlier by e.g. Frolking et al. (2006), and also shown by the calculations with impulse-response RF model, the current RF of a mire ecosystem depends mostly on its total C storage and its recent CH4 emission. Thus the RF can be quantified by multiplying these two input variables by the corresponding RF coefficients, with further refinement by addition of data on recent Carbon Accumulation Rate (CAR) and N2O emission. We propose a new metric for commensuration of the effects of Accumulated Carbon and Methane Emission (ACME) on Earth’s energy balance. This ACME approach is applicable to natural mires with a significant part of their carbon accumulated more than 1000 years ago. It provides an easy-to-use tool that requires few input data. Results and Discussion We demonstrate the feasibility of the ACME approach by applying it to a set of northern mires. The ACME-based RF estimates indicate that these mires have a cooling effect on the current climate, contrary to what a traditional GWP-based calculation suggests (Fig. 1). This exhibits a clear qualitative difference in the climatic effect of mire systems as suggested by these two approaches. The climatic effect as quantified by the ACME metric is dominated by the C accumulated into the mires over the millennia, which is ignored when using the GWPs and present-day fluxes. Furthermore, by applying the new metric with estimates of the global C storage and CH4 emission of mires north of 45°N, we can demonstrate their global cooling effect and estimate their current RF to range from –0.45 to –0.23 W m-2.

CCD-Rice: a long-term paddy rice distribution dataset in China at 30 m resolution

Abstract. As one of the most widely cultivated grain crops, paddy rice is a vital staple food in China and plays a crucial role in ensuring food security. Over the past decades, the planting area of paddy rice in China has shown substantial variability. Yet, there are no long-term high-resolution rice distribution maps in China, which hinders our ability to estimate greenhouse gas fluxes and crop production. This study developed a new optical satellite-based rice-mapping method using a machine learning model and appropriate data preprocessing strategies to mitigate the impact of cloud contamination and missing data in optical remote sensing observations on rice mapping. This study produced CCD-Rice (China Crop Dataset-Rice), the first high-resolution rice distribution dataset in China from 1990 to 2016. Based on 394 753 validation samples, the overall accuracy of the distribution maps in each provincial administrative region averaged 89.61 %. Compared with 20 544 county-level statistical data, the coefficients of determination (R2) of single- and double-season rice in each year averaged 0.85 and 0.78, respectively. The distribution maps can be obtained at https://doi.org/10.57760/sciencedb.15865 (Shen et al., 2024a).

Effects of different urban vegetation cover and green space types on soil greenhouse gas emissions and carbon sequestration

The development of urbanization has led to the creation of various types of green spaces, which have a direct influence on vegetation types and soil management, This, in turn, results in differences in soil carbon sequestration capacities. However, the factors affecting soil carbon sequestration in different vegetation types within urban green spaces remain largely unexplored. To address this gap, the study focused on the soil of urban green space. A one-year field observation was conducted, utilizing local management archives and historical data, to evaluate variations in soil greenhouse gas (GHG) emission and soil organic carbon sequestration across grassland (GL), shrubs (SH), and forests stands (FS) within three types of green spaces: park green space (P), residential green space (Ra), and street green space (s). The results indicated that: (1) In comparison to grassland (GL), the CO2 flux of shrubs (SH) and forests stands (FS) declined by 10.73% and 14.46%, respectively, while the N2O and CH4 fluxes remained insignificant. Additionally, the annual increase in soil organic carbon was lower by 8.92% and 10.80% in shrub and forests stand, respectively; (2) Variations in greenhouse gas fluxes were also observed among the three types of green spaces. In comparison to park green spaces, the CO2 flux of residential and street soils decreased by 2.11% and 3.25%, respectively, while the N2O flux dropped by 16.61% and 22.41%, respectively. The CH4 flux remained insignificant. The annual increase of SOC in residential and streets was notably lower than that in parks green spaces, by 9.59% and 15.20%, respectively, indicating significant differences. This suggests that soil carbon sequestration capacity is highly responsive to changes in vegetation coverage and green space types, with WSOC, NH4+-N, and pH identified as the primary factors influencing the greenhouse gas flux in the three soils. This study provides data and a theoretical basis for the strategic selection of urban soil management measures, particularly in the context of achieving carbon neutrality goals.

A practical metric for estimating the current climate forcing of natural mires

Abstract Commensuration of the radiative effects of different greenhouse gases (GHGs) is crucial for understanding the effects of land cover and ecosystem changes on the global climate. However, none of the current commensuration approaches are suitable for addressing the current climatic effect of mire ecosystems as compared to the situation in which such mires would not exist. The mire ecosystems have accumulated carbon for millennia, creating a negative perturbation to the atmospheric carbon dioxide content, but at the same time they emit methane into the atmosphere. Thus, the functioning of mires involves GHG fluxes with opposing effects on Earth’s radiative balance. Here, based on a simple radiative forcing (RF) model, we propose a new metric for commensuration of the effects of accumulated carbon and methane emission (ACME) on Earth’s energy balance. This ACME approach is applicable to natural mires with a significant part of their carbon accumulated more than 1000 years ago and requires relatively few input data. We demonstrate the feasibility of the ACME approach by applying it to a set of northern mires. The ACME-based RF estimate indicates that these mires have a cooling effect on the current climate, contrary to what a global warming potential-based calculation suggests, since the climatic effect is dominated by the sustained carbon accumulation. By applying the new metric with varying estimates of the total carbon storage and methane emission of northern mires, we estimate the current RF of these mires to range from –0.49 to –0.26 W m-2.

Springtime soil and tree stem greenhouse gas fluxes and the related soil microbiome pattern in a drained peatland forest

Spring can be a critical time of year for stem and soil methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) emissions as soil freeze–thaw events can be hot moments of gas release. Greenhouse gas fluxes from soil, Downy birch (Betula pubescens) and Norway spruce (Picea abies) stems were quantified using chamber systems and gas analysers in spring 2023 in a northern drained peatland forest. Dissolved gas concentrations in birch sap and soil water, environmental parameters, soil chemistry, and functional gene abundances in the soil were determined. During spring, initially low soil and stem CH4, N2O, and CO2 emissions increased towards late April. Temperature emerged as the primary driver of soil and stem fluxes, alongside photosynthetically active radiation influencing stem fluxes. Soil hydrologic conditions had minimal short-term impact. No clear evidence linked stem CH4 emissions to birch sap gas concentrations, while relationships existed for CO2. Functional gene abundances of the N and CH4-cycles changed between measurement days. Potential for methanogenesis and complete denitrification was higher under elevated soil water content, shifting to methanotrophy and incomplete denitrification as the study progressed. However, our results highlight the need for further analysis of relationships between microbial cycles and GHG fluxes under different environmental conditions, including identifying soil microbial processes in soil layers where tree roots absorb water.

Efficient Pollutant Removal and Low-Carbon Emission Mechanisms in Constructed Wetlands Synergistically Driven by Low COD/N Ratio and Coastal Location

Quantifying the variation in wetland greenhouse gas fluxes across large spatial scales and accurately assessing source–sink effects is crucial. However, there remains a limited understanding of the combined impacts of influent COD/N ratios and geographical distribution conditions on pollutant removal and GHG emissions. In this study, five typical constructed wetlands from across the country were selected to evaluate GHG emissions, pollutant removal efficiencies, and the main influencing factors for each wetland. The results showed that temperature, ammonia nitrogen concentration, COD, COD/N ratio, and geographical location were the main regulators of GHG emissions, with complex interactions among the factors. Overall, GHG emissions were higher in the coastal region than in the inland region, highlighting the importance of geographic distribution conditions on wetland operation. In addition, wetlands with a COD/N of 3 showed the best overall performance in terms of pollutant removal and GHG emission reduction. Moreover, COD/N had an important effect on the emission fluxes of all three greenhouse gases, which was an important influencing factor on the emission fluxes of greenhouse gases from constructed wetlands. Wetlands with lower COD/N ratios, especially coastal wetlands, showed stronger performance in pollutant removal and GHG emission reduction. This study emphasizes the need to fully consider the potential influence of influent COD/N ratio on GHG emissions when designing constructed wetlands for municipal wastewater treatment, providing valuable insights for future wetland design and GHG abatement strategies.

Short-term effect of grazing on net ecosystem exchange and fluxes of greenhouse gases in C3 and C4 pastures during the growing season

Short-term effect of grazing on net ecosystem exchange and fluxes of greenhouse gases in C3 and C4 pastures during the growing season

Human-induced N-P imbalances will aggravate GHG emissions from lakes and reservoirs under persisting eutrophication.

Human-induced N-P imbalances will aggravate GHG emissions from lakes and reservoirs under persisting eutrophication.

Differential river-to-sea transfers and CH4 dominance of greenhouse gas emissions in urbanized and impounded estuaries.

Differential river-to-sea transfers and CH4 dominance of greenhouse gas emissions in urbanized and impounded estuaries.

Soil Flooding Increases Greenhouse Gas Fluxes

Soil Flooding Increases Greenhouse Gas Fluxes

Seasonality and Vertical Structure of Microbial Communities in Alpine Wetlands.

The soil microbial community plays a crucial role in the elemental cycling and energy flow within wetland ecosystems. The temporal dynamics and spatial distribution of soil microbial communities are central topics in ecology. While numerous studies have focused on wetland microbial community structures at low altitudes, microbial diversity across seasons and depths and their environmental determinants remain poorly understudied. To test the seasonal variation in microbial communities with contrasting seasonal fluxes of greenhouse gases, a total of 36 soil samples were collected from different depths in the Namco wetland on the Tibetan Plateau across four seasons. We found significant seasonal variation in bacterial community composition, most pronounced in the Winter, but not in archaea. In particular, Proteobacteria decreased by 11.5% in Winter compared with other seasons (p < 0.05). The bacterial alpha diversity showed hump-shaped seasonal patterns with lower diversity in Winter, whereas archaea showed no significant patterns across depths. A PERMANOVA further revealed significant differences in the bacterial community structure between Winter and the other three seasons (p < 0.05). In addition, bacterial and archaeal community structures differed between surface (0-5 cm) and deeper (5-30 cm) soils (p < 0.01). Redundancy analysis showed that soil total nitrogen, soil total phosphorus, and total soil organic carbon significantly influenced bacteria and archaea (p < 0.05). Furthermore, soil moisture content and temperature strongly affected the bacterial community structure (p < 0.001). Our findings highlighted the seasonal variation in the microbial community and the profound influence of soil moisture and temperature on microbial structure in alpine wetlands on the Tibetan Plateau.