Variations in Ecosystem-Scale Methane Fluxes Across a Boreal Mire Complex Assessed by a Network of Flux Towers

Abstract

High latitude mires are key ecosystems in the context of climate change since they store large amounts of carbon while constituting an important natural source of methane (CH4). However, while a growing number of studies have investigated methane fluxes (FCH4) at the plot- (similar to 1 m(2)) and ecosystem-scale (similar to 0.1-0.5 km(2)) across the boreal biome, variations of FCH4 magnitudes and drivers at the mesoscale (i.e., 0.5-20 km(2)) of a mire complex are poorly understood. This study leveraged a network of four eddy-covariance flux towers to explore the spatio-temporal variations in ecosystem-scale FCH4 across a boreal mire complex in northern Sweden over 3 years (2020-2022). We found a consistent hierarchy of drivers for the temporal variability in FCH4 across the mire complex, with gross primary production and soil temperature jointly emerging as primary controls, whereas water table depth had no independent effect. In contrast, peat physical and chemical properties, particularly bulk density and C:N ratio, were identified as significant baseline constraints for the spatial variations in FCH4 across the mire complex. Our observations further revealed that the 3-year mean annual FCH4 across the mire complex ranged from 7 g C m(-2) y(-1) to 11 g C m(-2) y(-1), with a coefficient of variation of 16% that is similar to the variation observed among geographically distant mire systems and peatland types across the boreal biome. Thus, our findings highlight an additional source of uncertainty when scaling information from single-site studies to the mire complex scale and beyond. Furthermore, they suggest an urgent need for peatland ecosystem models to resolve the mesoscale variations in FCH4 at the mire complex level to reduce uncertainties in the predictions of peatland carbon cycle-climate feedbacks.

Keywords

climate change; eddy covariance; high latitude mires; landscape scale variations; mesoscale; methane emissions; northern peatlands; peat physical and chemical properties; peatland complex; spatio-temporal control

Published in

Global Change Biology
2025, volume: 31, number: 5, article number: e70223
Publisher: WILEY

SLU Authors

• Noumonvi, Koffi Dodji

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

• Nilsson, Mats

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

• Ratcliffe, Joshua

  • Unit for Field-based Forest Research, Swedish University of Agricultural Sciences
    
  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Öquist, Mats

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

• Järveoja, Järvi

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

• Simpson, Gillian

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

• Smeds, Jacob

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

• Peichl, Matthias

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

UKÄ Subject classification

Ecology
Environmental Sciences

Publication identifier

• DOI: https://doi.org/10.1111/gcb.70223

Permanent link to this page (URI)

https://res.slu.se/id/publ/141888