About the Trace Gas Biogeochemistry Group

A young man and woman draw water from a bog while squatting on a boardwalk.

About Us

We study the response of carbon, nitrogen and other element cycles to climate and land use change. Our research is located in subarctic, temperate, and tropical biomes that include tundra, forested, urban, and agricultural areas. We focus on trace gas biogeochemistry within these ecosystems, developing and utilizing a variety of techniques such as in-situ sensors, remote sensing, and process-based modeling from local to global scales. We work at the intersection between science and society, collaborating with students, educators, stakeholders, and citizens.

We seek to advance scientific discovery through collaboration, mentorship and outreach by building a strong, diverse and inclusive research community. We pursue questions of both fundamental scientific interest and broad societal relevance, while at the same time encouraging our group members’ unique motivations and interests and the benefits they bring. We communicate research in creative ways to increase the broader impact of our work by engaging stakeholders, the public and K-12 teachers and students.

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Principal Investigators

Ruth Varner
Alexandra Contosta

Research Staff

Apryl Perry
Florencia Fahnestock NA

Graduate Students

Apryl Perry – Drivers of CH4 ebullition in a temperate fen

Cheristy Jones – Terrestrial-Aquatic interaction in Arctic catchments

Shannon Van Hise – Assessing how forestry armoring mitigates soil disturbances during winter logging operations

Chelsea Oti – Microbial influence in methane oxidation in arctic lake sediments

Claudia Guillot-Wallace – Water-rock interactions in a peatland ecosystem undergoing permafrost thaw

Sadid Hossain – Impact of Seaweed-Supplemented Dairy Cow Excreta on Soil Greenhouse Gas Emissions

Brendan Murphy – Effects of livestock grazing on soil C & N

Peter Tansey – Effects of foundational species loss on soil carbon storage

Jannatul Ferdous – Focus is on Climate-Smart Agriculture, finding ways to reduce greenhouse gas emissions while improving soil health

<< Content coming soon  >>

  • From Archaea to the Atmosphere (NASA IDS: R. Varner PI) This project aims to scale emissions of methane across the arctic using a combination of microbial and isotopic measurements, UAS surveys to map vegetations, biogeochemical modeling and remote sensing. This project is part of NASA's Arctic Boreal Vulnerability Experiment (ABoVE).
  • Exploring the interactions between carbon cycling, land use and climate change (NASA CCS; J. Xiao PI). This project examines land use-climate interactions in the human-dominated region of southern New Hampshire that includes urban, suburban, agricultural, and forested land uses.
  • Soil carbon storage and greenhouse gas losses in intensively grazed pastures (USDA ORG; A. Contosta PI). This study explores linkages among grazing management, soil carbon storage, and greenhouse gas losses through a combination of field measurements, lab analyses, and process-based modeling. We are translating our research into a decision support system that will enable organic dairy farmers to make science-based pasture management decisions that promote soil C sequestration and reduce soil greenhouse gas emissions.
  • Promoting ecosystem services during the conversion of forests to fields in New England (USDA AFRI; R. Smith PI). This project seeks to determine how forest-to-agriculture conversions, particularly pasture and silvopasture, affect ecosystem services such as nutrient retention, water availability, climate regulation, and forage supply.
  • Winter Climate Change in the Northern Forest (NSRC; A. Contosta). The goal of this work is to determine how climate change impacts winter ecological and biogeochemical processes, and how this changing winter landscape affects Northern Forest communities.
  • Winter Weather Whiplash (SESYNC; A. Contosta). This project is developing a suite of winter weather whiplash indices and associated physical, ecological, biogeochemical, and socioeconomic response metrics to determine the extent to which winter weather whiplash events have cascading impacts on ecosystems and their services.
  • DOE funded Isogenie project (R. Varner).
  • Global Sustainable Bioenergy Initiative (N. Campbell).
  • Bringing DNDC into the Predictive Ecosystem Analyzer (PEcAn) project (ESRC; R. Varner, A. Contosta, N. Campbell). This project is expanding our capacity for ecosystem model analyses at scales relevant for policy and land management by integrating the ecosystem model DeNitrification-DeComposition (DNDC) into the PEcAn system.

Trace gas analysis using CH4 using a gas chromatograph equipped with a flame ionization detector (GC-FID; Shimadzu 8A); and CH4, CO2, and H2O vapor  (Cavity Enhanced Absorption Spectroscopy (OF-CEAS); LI-COR 7810).  We also have a laser to measure del13-CH4 (Aerodyne, Inc.).

Yousuf, M. F., Siddique, T., Mahmud, M. S., Campbell, J. L., Contosta, A., & Burakowski, E. (2025). Innovative Pressure-Sensing Wireless Network for High-Resolution Real-Time Monitoring of Soil Frost Depth and Freeze/Thaw Dynamics. IEEE Sensors Journal, 25(17), 33564-33578. doi:10.1109/jsen.2025.3589914

Pastore, M. A., Nelson, S. J., Burakowski, E. A., Contosta, A. R., D'Amato, A. W., Garlick, S., . . . Weiskittel, A. (2025). Snow refugia: Managing temperate forest canopies to maintain winter conditions. Ecosphere, 16(7). doi:10.1002/ecs2.70302

Li, Z., Riley, W. J., Marschmann, G. L., Karaoz, U., Shirley, I. A., Wu, Q., . . . Brodie, E. L. (2025). A framework for integrating genomics, microbial traits, and ecosystem biogeochemistry.. Nat Commun, 16(1), 2186. doi:10.1038/s41467-025-57386-5

Blais, N. D., O’Brien, J. M., Holland-Moritz, H., Farnsworth, L., Barbato, R. A., Douglas, T. A., . . . Ernakovich, J. G. (2025). Permafrost pore structure and its influence on microbial diversity: Insights from X-ray computed tomography. Geoderma, 454, 117192. doi:10.1016/j.geoderma.2025.117192

Bechtold, E. K., Ellenbogen, J. B., Villa, J. A., de Melo Ferreira, D. K., Oliverio, A. M., Kostka, J. E., . . . Wilkins, M. J. (2025). Metabolic interactions underpinning high methane fluxes across terrestrial freshwater wetlands.. Nat Commun, 16(1), 944. doi:10.1038/s41467-025-56133-0

Herreid, A. M., Fazekas, H. M., Nelson, S. J., Wymore, A. S., Murray, D., Varner, R. K., & McDowell, W. H. (2025). Climate displaces deposition as dominant driver of dissolved organic carbon concentrations in historically acidified lakes.. Biogeochemistry, 168(1), 5. doi: 10.1007/s10533-024-01193-5

Wilson, G., Green, M., Campbell, J., Contosta, A., Lany, N., & Bailey, A. (2024). Long-term measurements of seasonal snowpacks indicate increases in mid-winter snowmelt and earlier snowpack disappearance in the northeastern U.S.. PLOS Climate, 3(12), e0000529. doi:10.1371/journal.pclm.0000529

Knorr, M. A., Contosta, A. R., Morrison, E. W., Muratore, T. J., Anthony, M. A., Stoica, I., . . . Frey, S. D. (2024). Unexpected sustained soil carbon flux in response to simultaneous warming and nitrogen enrichment compared with single factors alone.. Nat Ecol Evol, 8(12), 2277-2285. doi:10.1038/s41559-024-02546-x

Kuhn, M. A., Varner, R. K., McCalley, C. K., Perryman, C. R., Aurela, M., Burke, S. A., . . . Waldrop, M. P. (2024). Controls on Stable Methane Isotope Values in Northern Peatlands and Potential Shifts in Values Under Permafrost Thaw Scenarios. Journal of Geophysical Research: Biogeosciences, 129(7). doi:10.1029/2023jg007837

Perryman, C. R., McCalley, C. K., Shorter, J. H., Perry, A. L., White, N., Dziurzynski, A., & Varner, R. K. (2024). Effect of Drought and Heavy Precipitation on CH4 Emissions and δ13C–CH4 in a Northern Temperate Peatland. Ecosystems, 27(1), 1-18. doi:10.1007/s10021-023-00868-8