Methane fluxes in tidal marshes of the conterminous United States

Ariane Arias-Ortiz; Jaxine Wolfe; Scott D. Bridgham; Sara Knox; Gavin McNicol; Brian A. Needelman; Julie Shahan; Ellen J. Stuart-Haëntjens; Lisamarie Windham-Myers; Patty Oikawa; Dennis D. Baldocchi; Joshua S. Caplan; Margaret Capooci; Kenneth M. Czapla; R. Kyle Derby; Heida L. Diefenderfer; Inke Forbrich; Gina Groseclose; Jason Keller; Cheryl Kelley; Amr E. Keshta; Helena S. Kleiner; Ken W. Krauss; Robert R. Lane; Sarah Mack; Serena Moseman-Valtierra; Thomas Mozdzer; Peter Mueller; Scott C. Neubauer; Genevieve Noyce; Karina V.R. Schäfer; Rebecca Sanders-DeMott; Charles A Schutte; Rodrigo Vargas; Nathaniel B Weston; Benjamin Wilson; J. Patrick Megonigal; James R. Holmquist

doi:10.1111/gcb.17462

Home/Archive/USGS

USGS · 70277021

Methane fluxes in tidal marshes of the conterminous United States

View original source ↗Export metadata ↓

Abstract

Methane (CH 4 ) is a potent greenhouse gas (GHG) with atmospheric concentrations that have nearly tripled since pre-industrial times. Wetlands account for a large share of global CH 4 emissions, yet the magnitude and factors controlling CH 4 fluxes in tidal wetlands remain uncertain. We synthesized CH 4 flux data from 100 chamber and 9 eddy covariance (EC) sites across tidal marshes in the conterminous United States to assess controlling factors and improve predictions of CH 4 emissions. This effort included creating an open-source database of chamber-based GHG fluxes ( https://doi.org/10.25573/serc.14227085 ). Annual fluxes across chamber and EC sites averaged 26 ± 53 g CH 4 m −2 year −1 , with a median of 3.9 g CH 4 m −2 year −1 , and only 25% of sites exceeding 18 g CH 4 m −2 year −1 . The highest fluxes were observed at fresh-oligohaline sites with daily maximum temperature normals (MATmax) above 25.6°C. These were followed by frequently inundated low and mid-fresh-oligohaline marshes with MATmax ≤25.6°C, and mesohaline sites with MATmax >19°C. Quantile regressions of paired chamber CH 4 flux and porewater biogeochemistry revealed that the 90th percentile of fluxes fell below 5 ± 3 nmol m −2 s −1 at sulfate concentrations >4.7 ± 0.6 mM, porewater salinity >21 ± 2 psu, or surface water salinity >15 ± 3 psu. Across sites, salinity was the dominant predictor of annual CH 4 fluxes, while within sites, temperature, gross primary productivity (GPP), and tidal height controlled variability at diel and seasonal scales. At the diel scale, GPP preceded temperature in importance for predicting CH 4 flux changes, while the opposite was observed at the seasonal scale. Water levels influenced the timing and pathway of diel CH 4 fluxes, with pulsed releases of stored CH 4 at low to rising tide. This study provides data and methods to improve tidal marsh CH 4 emission estimates, support blue carbon assessments, and refine national and global GHG inventories.

Explore related subjects

Global Change Biology Article

Source-reported bounding extent: 25.08° to 49.38905° latitude; -124.68721° to -66.96466° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Ariane Arias-Ortiz, Jaxine Wolfe, Scott D. Bridgham, Sara Knox, Gavin McNicol, Brian A. Needelman, Julie Shahan, Ellen J. Stuart-Haëntjens, Lisamarie Windham-Myers, Patty Oikawa, Dennis D. Baldocchi, Joshua S. Caplan, Margaret Capooci, Kenneth M. Czapla, R. Kyle Derby, Heida L. Diefenderfer, Inke Forbrich, Gina Groseclose, Jason Keller, Cheryl Kelley, Amr E. Keshta, Helena S. Kleiner, Ken W. Krauss, Robert R. Lane, Sarah Mack, Serena Moseman-Valtierra, Thomas Mozdzer, Peter Mueller, Scott C. Neubauer, Genevieve Noyce, Karina V.R. Schäfer, Rebecca Sanders-DeMott, Charles A Schutte, Rodrigo Vargas, Nathaniel B Weston, Benjamin Wilson, J. Patrick Megonigal, James R. Holmquist. 2024-09-05. Methane fluxes in tidal marshes of the conterminous United States. https://doi.org/10.1111/gcb.17462

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Phenological flexibility in nesting grassland birds over a half century informs timing of management

The timing of biological events for wildlife species reflects and influences ecological and evolutionary processes and helps guide management actions to meet conservation objectives. Climate change may cause phenological shifts across trophic levels and ecosystems, which can have broad ecological impacts. Shifts may also result in mistiming between management practices based on historical conditions and current biological events, reducing the effectiveness of natural resource management and conservation efforts. We analyzed nesting phenology patterns over recent decades across North America for 44 species of grassland-nesting birds, including waterfowl, upland gamebirds, shorebirds, and passerines, many of which have experienced precipitous population declines. Understanding nesting phenologies of these species is important to their conservation, as grassland management activities often conflict with reproductive periods leading to high nest and young mortality. We compiled a dataset of over 172,000 nest records spanning five decades and evaluated environmental factors influencing long-term shifts and short-term flexibility in nesting phenology. We found considerable variation in responses among species, with differences in both direction and magnitude of spatiotemporal effects on nest initiation dates. Notably, the community-level nesting season lengthened over time, but shifts exhibited spatial heterogeneity within this community of grassland birds. Nesting dates shifted asymmetrically across the breeding season with differential changes in early, peak, and late nesting dates whereas long-term changes were mediated by weather and geographic gradients. For example, nest initiation was earlier in warmer and wetter years. By applying a quantile-based analysis, we provide estimates of the full nesting period that could serve as a flexible tool for scheduling monitoring efforts and balancing management and human activities with periods of reduced nesting activity. Our collaborative effort illustrates the challenges and opportunities of collecting long-term data on avian communities necessary for answering questions across large regions but highlights the value of research coordination for bird conservation.

Global Change Biology↗

USGS2026

Water quality improvements and hydrogeomorphic change over 20 years contributed to macrophyte community recovery in the Upper Mississippi River

Several large rivers across the globe have recently undergone noticeable improvements to water quality. Yet, the cascading ecological consequences for aquatic life, including macrophytes, are largely unknown, owing to the lack of suitable long-term data and the difficulty of modelling community-level responses. Our study leveraged multiple big datasets from 1998 to 2019 within a 400-km stretch of the Upper Mississippi River in the United States, which experienced major changes to hydrogeomorphology, water quality, and climate during the 22-year study. These decadal changes resulted from both natural processes, such as increased discharge and hydrologic connectivity, and targeted management actions, including water quality improvements and restorations. Using joint species distribution models, we showed how changes to hydrogeomorphology and water quality increased macrophyte taxonomic and ecological (trait) diversity at a macroscale. We uncovered substantial macrophyte community recovery as evidenced by increased species prevalence and diversity, as well as favorable community trait shifts from undesirable free-floating plants towards desirable submersed plants. Submersed species were positively associated with water quality improvements (specifically, reduced concentrations of total phosphorus, chlorophyll a , and total suspended solids). However, total nitrogen concentration modestly increased over the 22-year period and nearly all macrophyte species were locally absent or negatively affected by high nitrogen values. Pollination mode and life form traits responded to environmental changes; as examples, submersed plants recovered with water quality improvements and epihydrophilous plants that pollinate on the water's surface increased with hydrogeomorphic connectivity. Water quality improvements explained approximately 25%–40% of the macrophyte community's temporal variation. Other major environmental drivers of macrophyte distribution included spatial variations of water depth and velocity. Macrophyte community assembly was shaped partially by strong temporal changes in hydrogeomorphology and water quality, and to a greater extent the spatial habitat heterogeneity within the large riverscape.

Iowa, Illinois, Minnesota, Wisconsin↗

USGS2026

Adaptation and response in drylands: A dryland research agenda and campaign strategy

Dryland ecosystems cover 41% of Earth's land surfaces, account for 44% of cultivated lands and 60% of food sources, and make large contributions to the global water and carbon cycles. However, these ecosystems are experiencing unprecedented extremes including heatwaves, floods, and droughts as well as hotter temperatures and often declining water resource availability. These ecosystems are some of the most challenging to monitor given their high temporal variability with rapid response to their environment as well as vast spatial variability with intermixing of different plant species and life forms amongst bare soil coverage. The Adaptation and Response in Drylands (ARID) campaign was selected by National Aeronautics and Space Administration (NASA) as a scoping study to develop a research agenda for a dryland field campaign. Here, we detail our ARID science research agenda and implementation plan that were developed based on an extensive community engagement effort in over 160 events with over a thousand scientists, land managers, and Tribal communities between 2023 and 2024. The selected science themes cover drought and climate variability, ecosystem structure, function, and biodiversity, carbon cycle interannual variability and trends, and social ecological systems (land management and adaptation). We then detail our remote sensing, modeling, and field-based strategies to capture high temporal and high spatial resolution processes. Finally, our implementation strategy is presented which includes focus area selections in a core intensive western U.S. domain and distributed international domains. This strategy includes our overarching guiding principles of using multi-temporal airborne acquisitions and super sites as well as enhancing land management in co-development with end-user partners. While originally developed for NASA, our ARID report creates a blueprint for any future dryland field campaign, at any scale, that can be implemented widely for foundational and applied science objectives.

Global Change Biology↗