Upscaling methane fluxes from peatlands across a drainage gradient in Ireland using PlanetScope imagery and machine learning tools

Wetlands are one of the major contributors of methane (CH4) emissions to the atmosphere and the intensity of emissions is driven by local environmental variables and spatial heterogeneity. Peatlands are a major wetland class and there are numerous studies that provide estimates of methane emissions at chamber or eddy covariance scales, but these are not often aggregated to the site/ecosystem scale. This study provides a robust approach to map dominant vegetation communities and to use these areas to upscale methane fluxes from chamber to site scale using a simple weighted-area approach. The proposed methodology was tested at three peatlands in Ireland over a duration of 2 years. The annual vegetation maps showed an accuracy ranging from 83 to 99% for near-natural to degraded sites respectively. The upscaled fluxes were highest (2.25 and 3.80 gC m(-2) y(-1)) at the near-natural site and the rehabilitation (0.17 and 0.31 gC m(-2) y(-1)), degraded (0.15 and 0.27 gC m(-2) y(-1)) site emissions were close to net-zero throughout the study duration. Overall, the easy to implement methodology proposed in this study can be applied across various landuse types to assess the impact of peatland rehabilitation on methane emissions by mapping ecological change.

Automated summary

Wetlands, particularly peatlands, are significant sources of methane emissions. This study presents a reliable method to upscale methane fluxes from small-scale observations to large-scale estimates using vegetation mapping. The proposed methodology was successfully tested in three peatlands in Ireland. Overall, this easy to implement approach can be applied across different land types to evaluate the impact of peatland rehabilitation on methane emissions.