Changes in Aquatic Carbon Following Rewetting of a Nutrient-Poor Northern Peatland

Abstract

Rewetting drained peatlands by raising the groundwater table is currently suggested, and widely implemented, as an efficient measure to reduce peat soil degradation and decrease CO2 emissions. However, limited information exists regarding effects of peatland rewetting on lateral carbon export (LCE) via the aquatic pathway. Any changes in LCE are critical to consider, as they affect the overall peatland C balance, and may offset any climatic benefits from rewetting. Additionally, altered LCE could have consequences for downstream water quality and biota. Here, we monitored aquatic C content (DOC, DIC and CH4) in runoff and pore water, as well as radiocarbon content of DOC in runoff from a drained, nutrient-poor boreal peatland that was rewetted during autumn 2020. By comparing pre- (2019-2020) and post- (2021-2022) rewetting periods, we detected changes in the aquatic C export. The results showed that the rewetting effect was site-, season- and C form-specific. Overall, one catchment showed elevated (DOC, DIC) or highly elevated (CH4) concentrations and exports post-rewetting, whereas the other site showed only elevated DOC. Changes in runoff C concentrations after rewetting were likely driven by site-specific factors such as expansion of open-water areas, altered hydrological flow paths and proportion of filled in ditches of total ditch length. Finally, radiocarbon measurements indicated enhanced export of contemporary DOC via runoff following rewetting. These initial (short-term) findings highlight the need for site-specific before-after assessments to better evaluate the C sequestration capacity of peatlands while undergoing rewetting operations.

Keywords

boreal; lateral carbon export; methane; ditches; hydrological connectivity; radiocarbon

Published in

Journal of Geophysical Research: Biogeosciences
2025, volume: 130, number: 4, article number: e2024JG008565
Publisher: AMER GEOPHYSICAL UNION

SLU Authors

• Zannella, Alberto

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Eklöf, Karin

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Maher Hasselquist, Eliza

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Wallin, Marcus

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences
Geosciences, Multidisciplinary

Publication identifier

• DOI: https://doi.org/10.1029/2024JG008565

Permanent link to this page (URI)

https://res.slu.se/id/publ/141507