Environmental drivers of gaseous carbon fluxes in drained and rewetted Minnesota peatlands, U. S. A.

Abstract Introduction Rewetting shows promise for mitigating carbon loss from drained peatlands. However, knowledge gaps remain in rewetting impacts on gaseous carbon fluxes and factors affecting rewetting success, especially in Minnesota and the Upper Midwest, United States, despite abundant degraded peatlands presenting restoration opportunities. Objectives This study fills knowledge gaps in carbon flux from partially drained and rewetted Minnesota peatlands and quantifies environmental drivers of gaseous carbon fluxes to better estimate peatland carbon flux throughout Minnesota and the region. Methods We paired chamber‐based ecosystem respiration ( R eco ), net ecosystem exchange (NEE), and methane (CH 4 ) flux measurements with measurements of environmental variables. We used a linear mixed‐effects model comparison approach to identify important environmental drivers of gaseous carbon flux. Results Overall, R eco and NEE were lower and CH 4 fluxes higher at the rewetted site versus the drained site (4.42 vs. 11.21 μmol CO 2 m − 2 s −1 , 2.57 versus 5.26 μmol CO 2 m − 2 s −1 , and 18.69 versus 3.58 nmol CH 4 m − 2 s −1 , respectively). Open water produced extremely high CH 4 fluxes at both sites. Water table depth, sphagnum cover, grass/sedge cover, restoration status, and pH predicted CH 4 flux; sphagnum cover, soil temperature, and pH predicted R eco ; and sphagnum cover, restoration status, and soil temperature predicted NEE. Conclusions The results add to a growing body of research demonstrating peatland rewetting effects on carbon fluxes, allowing comparison of Minnesota drainage‐impacted peatland fluxes to global measurements. Additionally, strong associations identified between field‐measured environmental characteristics and gaseous carbon fluxes may aid in scaling flux estimates.