Understanding trends in wood production and carbon sequestration in the Northern Forest region is critical for societal priorities related to climate mitigation, economic development and managing for resilient forests of the future. Despite a wealth of research on forest carbon cycling, researchers still do not have a sense of how these variables will change in the coming years. At the Bartlet Experimental Forest in NH, data from an intensively studied carbon flux research site indicate decadal-scale reductions in wood growth and carbon storage, but an increase total carbon uptake by photosynthesis. These contrasting trends are surprising, but are consistent with emerging data pertaining to the effects of rising atmospheric CO2 on plant growth and nutrient availability.

Increasing evidence from research sites in the Northern Forest region and elsewhere suggest that rising CO2 has caused declines in nitrogen (N) availability by increasing N demand and reducing decomposition through production of more carbon-rich plant litter. The proposed research will assess the degree to which relations among wood growth, carbon sequestration and N availability has changed over time by revisiting a network of plots that our research team last sampled 25 years ago. We will supplement this approach by making additional carbon flux measurements at the Bartlett and Howland, Maine carbon flux tower sites that will clarify mechanisms responsible for observed trends. This approach represents a unique opportunity to resolve questions about forest growth and carbon sequestration that will help plan for more sustainable and resilient forests of the future.

Publications:

Bergl, D.D., Carbone, M.S., Hollinger, D., Liu, Y., Lucas, B., Ollinger, S.V., Ouimette, A.P., Templer, P., Richardson, A.D. Increasing Respiration Weakens the Carbon Sink over Two Decades in a Temperate Deciduous Forest. Global Change Biology Communications.

Ouimette, A.P., Hastings, J.H., D’Amato, T., Battles, J.J., Ducey, M., Foster, J.R., Fuss, C., Goodale, C., Johnson, C., Lang, A., Ollinger, S.V., 2026. Can Coarse Woody Material Account for the Nitrogen Imbalance at Hubbard Brook Experimental Forest, New Hampshire, USA? Biogeochemistry.

Liu, Y., Stoy, P., Chu, H., Hollinger, D.Y., Ollinger, S.V., Ouimette, A.P., Durden, D.J., Sturtevant, C., Lucas, B. and Richardson, A.D., 2026. A tale of two towers: comparing NEON and AmeriFlux data streams at Bartlett Experimental Forest. Agricultural and Forest Meteorology, 378, p.110939.

Sullivan, F.B., Hastings, J.H., Ollinger, S.V., Ouimette, A., Richardson, A.D. and Palace, M., 2026. Parsing the Relative Contributions of Leaf and Canopy Traits in Airborne Spectrometer Measurements. Remote Sensing, 18(2), p.355.

Zhou, Z., Gustafson, E.J., Ollinger, S.V., Ouimette, A.P., Miranda, B.R., Duveneck, M.J., Foster, J.R., Sturtevant, B.R., Bronson, D.R. and Laflower, D., 2025. Integrating nitrogen and carbon cycling into LANDIS-II/PnET-Succession to improve forest landscape modeling: methods and sensitivity analyses. Ecological Modelling, 510, p.111285. 

Presentations: 

Dionis, J., Kotulak, A., Contosta, A., Ouimette, A., Blommel, C., Hastings, J., Tetreault, E., Vandewater, V., Ollinger, S.V., 2025. Assessing Shifts in Carbon Allocation Over Two Decades in a Mixed Northern Hardwood Forest. Poster presentation at the American Geophysical Union Annual Meeting, New Orleans, LA, December 15-19.

Kotulak, A., Dionis, J., Frey, S., Ouimette, A., Blommel, C., Hastings, J.H., Tetreault, E., Vandewater, V., Ollinger, S.V., 2025. Long-Term Patterns of Forest Productivity and Nitrogen Availability in a Northeastern Temperate Forest. Poster presentation at the American Geophysical Union Annual Meeting, New Orleans, LA, December 15-19.

Dionis, J., 2025. Is rising atmospheric CO₂ and nutrient limitation driving changes in carbon allocation in northeastern temperate forests? Talk at the UNH Department of Natural Resources Spring Seminar.

Kotulak, A., 2025. Long-term changes in forest C allocation, N availability, and mediation by mycorrhizal fungi. Talk at the UNH Department of Natural Resources Spring Seminar.

Student Involvement:

John Dionis, MS
Arielle Kotulak, MS