The impact of warming on peak-season ecosystem carbon uptake is influenced by dominant species in warmer sites

Authors: BRINKHOFF, ROSE - University Of Michigan; SANDERS, NATHAN - University Of Michigan; HENNING, JEREMIAH - University Of South Alabama; NEWMAN, GREG - University Of Oklahoma; Read, Quentin; SUNDQVIST, MAJA - Swedish University Of Agricultural Sciences; HOVENDEN, MARK - University Of Tasmania; PRAGER, CASE - University Of Michigan; REWCASTLE, KENNA - University Of Michigan; SOUZA, LARA - University Of Oklahoma; VOUGHT, OLIVIA - University Of Michigan; CLASSEN, AIMEE - University Of Michigan

Submitted to: Journal of Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2025
Publication Date: 2/5/2026
Citation: Brinkhoff, R.E., Sanders, N.J., Henning, J.A., Newman, G., Read, Q.D., Sundqvist, M.K., Hovenden, M.J., Prager, C.M., Rewcastle, K.E., Souza, L., Vought, O.K., Classen, A.T. 2026. The impact of warming on peak-season ecosystem carbon uptake is influenced by dominant species in warmer sites. Journal of Ecology. 114(2),e70247. https://doi.org/10.1111/1365-2745.70247.
DOI: https://doi.org/10.1111/1365-2745.70247

Interpretive Summary: Mountain ecosystems are disproportionally affected by ongoing climate warming. As the climate warms, it is vital for us to monitor the flow of carbon (C) in and out of living biomass at the ecosystem level. Warming can affect the rates of carbon exchange in ecosystems (plants taking up C by photosynthesis, and all organisms releasing C by respiration). In addition, as human-caused changes cause species to increase and decrease in abundance, the ecosystem-level rate of C exchange can go up and down based on changes in which species are most common. In this study, we experimentally warmed mountain ecosystems and crossed the warming treatment with removal of the dominant (most common) plant species, at both high and low elevation. We found that dominant species removal had bigger impacts on ecosystem C uptake than warming, and that the effect was strongest at the low-elevation site. These effects varied from year to year, resulting in each system being a net C source in some years and a net C sink in others. These findings are important for our understanding of how warming and changes in species abundance interact to influence C flows, and how this changes over space and throughout time.

Technical Abstract: Climatic warming influences ecosystem-scale carbon fluxes directly via its effect on photosynthesis and respiration, and indirectly via effects on the plant community. Here, we report on a 10-year factorial warming and dominant plant species removal experiment established in montane meadows in the Rocky Mountains (USA) at high and low elevations to explore how dominant plants modify the effect of warming on the carbon cycle across space and over time. The removal of dominant plants reduced the effect of warming on net ecosystem carbon exchange (NEE) at the low-elevation site in most years. Gross primary productivity (GPP) was generally reduced by the removal of the dominant species, but the effects of warming were minimal. The impact of warming and dominant species removal treatments on ecosystem respiration (ER) varied from year to year at the low-elevation site. Interestingly, across years montane meadow plant communities switched between having a net uptake and net release of carbon at both low and high elevations. Finally, carbon fluxes at the high-elevation site were largely unaffected by the removal or warming treatments. Taken together, these results raise three important points: dominant plant species can mediate the impacts of warming on carbon fluxes, terrestrial ecosystems can be both carbon sources and sinks, and this can vary spatially and temporally.