Earlier snowmelt increases the strength of the carbon sink in montane meadows unequally across the growing season

Journal Article · Thu Nov 06 00:00:00 EST 2025 · Journal of Ecology

DOI:https://doi.org/10.1111/1365-2745.70195· OSTI ID:3013959

Vought, Olivia K. ^[1]; Kivlin, Stephanie N. ^[2]; Shulman, Hannah B. ^[2]; Sorensen, Patrick O. ^[3]; Inouye, David W. ^[4]; Ibáñez, Inés ^[5]; Falb, Peter ^[5]; Rand, Karin ^[6]; Classen, Aimée T. ^[6]

---

1. Univ. of Michigan, Ann Arbor, MI (United States); Rocky Mountain Biological Laboratory, Crested Butte, CO (United States)
2. Univ. of Tennessee, Knoxville, TN (United States)
3. Univ. of Rhode Island, Kingston, RI (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
4. Rocky Mountain Biological Laboratory, Crested Butte, CO (United States); Univ. of Maryland, College Park, MD (United States)
5. Univ. of Michigan, Ann Arbor, MI (United States)
6. Univ. of Michigan, Ann Arbor, MI (United States); Univ. of Michigan Biological Station (UMBS), Pellston, MI (United States)

1. Warming temperatures are changing winters, leading to earlier snowmelt. This shift can lead to an earlier and potentially longer growing season, which in turn may affect various plant-mediated ecosystem functions. Despite its relevance in the carbon cycle, we still know little about how earlier snowmelt impacts the carbon balance in ecosystems over the growing season, for example, does it only shift phenology, or does it affect the overall carbon uptake? Most studies rely on interannual variability in snowmelt timing, making it difficult to isolate snowmelt effects from other confounding variables, for example, temperature and moisture anomalies. To address this uncertainty, we investigated how experimentally advancing snowmelt affects the carbon cycling of montane meadows across the growing season. 2. We experimentally advanced the snowmelt date in a montane meadow by approximately 12 days and collected data every 2 weeks throughout the growing season, including net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (ER), plant composition, and shrub, graminoid, and forb biomass. 3. Early in the growing season, GPP was higher in the early snowmelt plots, though this effect decreased as the growing season progressed. Our modelling of cumulative NEE showed a possible 22% increase in the carbon sink strength with earlier snowmelt. The effect was strongest in the early spring and diminished as the growing season progressed, with control plots being a greater carbon sink in the later season. Graminoid biomass was 47% higher in plots with earlier snowmelt, but there was no change in total biomass. 4. Synthesis. As winters warm and snowmelt occurs earlier, plant productivity will shift earlier in the growing season, and montane meadows may become a stronger carbon sink. However, this effect will differ seasonally, altering the carbon balance in montane meadows.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER). Earth & Environmental Systems Science (EESS)
• Grant/Contract Number: AC02-05CH11231
• Other Award/Contract Number: FOA-0002392
• OSTI ID: 3013959
• Journal Information: Journal of Ecology, Journal Name: Journal of Ecology Journal Issue: 12 Vol. 113; ISSN 0022-0477; ISSN 1365-2745
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

carbon cycle
climate change
ecosystem respiration
gross primary productivity
montane meadow
net ecosystem exchange
plant community
snowmelt