Montane Meadows: A Soil Carbon Sink or Source?

• Published in: Ecosystems (New York) Vol. 24; no. 5; pp. 1125 - 1141
• Main Authors: Reed, Cody C., Merrill, Amy G., Drew, W. Mark, Christman, Beth, Hutchinson, Rachel A., Keszey, Levi, Odell, Melissa, Swanson, Sherman, Verburg, Paul S. J., Wilcox, Jim, Hart, Stephen C., Sullivan, Benjamin W.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2021; Springer; Springer Nature B.V
• Subjects: Anthropogenic factors; Atmosphere; Biomedical and Life Sciences; Carbon; Carbon content; Carbon sinks; Climate change; Ecology; Ecosystems; Emissions; Environmental Management; Environmental policy; Fluctuations; Functional groups; Geoecology/Natural Processes; Global temperature changes; Greenhouse gases; Human influences; Hydrology/Water Resources; Land area; Life Sciences; Meadows; Net losses; Peatlands; Plant Sciences; Regional development; Respiration; Soils; Vegetation; Zoology; Climate change; Montane meadow; Subalpine; Carbon budget; Carbon sequestration; Peatland; Wetland; Carbon loss
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-020-00572-x

As the largest biogeochemically active terrestrial reserve of carbon (C), soils have the potential to either mitigate or amplify rates of climate change. Ecosystems with large C stocks and high rates of soil C sequestration, in particular, may have outsized impacts on regional and global C cycles. Montane meadows have large soil C stocks relative to surrounding ecosystems. However, anthropogenic disturbances in many meadows may have altered the balance of C inputs and outputs, potentially converting these soils from net C sinks to net sources of C to the atmosphere. Here, we quantified ecosystem-level C inputs and outputs to estimate the annual net soil C flux from 13 montane meadows spanning a range of conditions throughout the California Sierra Nevada. Our results suggest that meadow soils can be either large net C sinks (577.6 ± 250.5 g C m −2 y −1 ) or sources of C to the atmosphere (− 391.6 ± 154.2 g C m −2 y −1 ). Variation in the direction and magnitude of net soil C flux appears to be driven by belowground C inputs. Vegetation species and functional group composition were not associated with the direction of net C flux, but climate and watershed characteristics were. Our results demonstrate that, per unit area, montane meadows hold a greater potential for C sequestration than the surrounding forest. However, legacies of disturbance have converted some meadows to strong net C sources. Accurate quantification of ecosystem-level C fluxes is critical for the development of regional C budgets and achieving global emissions goals.