2024 Abstracts

The Effect of Accelerated Snowmelt on Carbon Cycling Across a Growing Season


Olivia Vought1* (ovought@umich.edu), Patrick Sorensen2, Hannah Shulman3, Peter Falb1, David Inouye4, Aimée Classen1,5, Stephanie Kivlin3


1University of Michigan, Ann Arbor, MI; 2Lawrence Berkeley National Laboratory, Berkeley, CA; 3University of Tennessee, Knoxville, TN; 4University of Maryland, College Park, MD; 5University of Michigan Biological Station, Pellston, MI


Climate change impacts snowmelt timing, which has cascading effects on ecosystems. Earlier snowmelt can lengthen the growing season of plants or shift plant phenology to earlier in the year but maintain the same season length. The team explored how an accelerated snowmelt date of approximately two weeks impacted the ecosystem respiration, production, and plant biomass in a montane meadow ecosystem over the growing season. Researchers measured NEE (net ecosystem exchange), GPP (gross primary productivity), ER (ecosystem respiration), shrub biomass, graminoid biomass, forb biomass, air temperature, and soil moisture biweekly in five early snowmelt and five control plots from early June to mid-August 2023. The team found that an earlier snowmelt date impacts the productivity of plants by shifting the growing season earlier in the year. However, early snowmelt does not affect overall net ecosystem exchange, as ecosystem respiration remains unchanged. Using a Bayesian model, researchers found that with earlier snowmelt, gross primary productivity is limited by soil moisture more than in control plots, and the negative effect of drought increases as the growing season progresses. Surprisingly, it was found that an earlier snowmelt date did not significantly affect the plant biomass of any functional group (all long-lived perennials). However, the impact of an earlier snowmelt date on the relative abundance of each plant species could explain the shift in plant productivity. As winters become warmer and snowmelt advances, plant productivity will shift to earlier in the growing season and be limited by decreased soil moisture. Consequences of altered plant phenology on other ecosystem components, including associations with belowground mutualists and nutrient retention in soils, are the targets for the remainder of this grant. This data will allow the team to model the relative importance of abiotic conditions, aboveground, and belowground biota on carbon cycling throughout the growing season in response to accelerated snowmelt.