High-Resolution Classification of South Patagonian Peat Bog Microforms Reveals Potential Gaps in Up-Scaled CH4 Fluxes by use of Unmanned Aerial System (UAS) and CIR Imagery

Abstract

South Patagonian peat bogs are little studied sources of methane (CH 4 ). Since CH 4 fluxes can vary greatly on a small scale of meters, high-quality maps are needed to accurately quantify CH 4 fluxes from bogs. We used high-resolution color infrared (CIR) images captured by an Unmanned Aerial System (UAS) to investigate potential uncertainties in total ecosystem CH 4 fluxes introduced by the classification of the surface area. An object-based approach was used to classify vegetation both on species and microform level. We achieved an overall Kappa Index of Agreement (KIA) of 0.90 for the species-and 0.83 for the microform-level classification, respectively. CH 4 fluxes were determined by closed chamber measurements on four predominant microforms of the studied bog. Both classification approaches were employed to up-scale CH 4 closed chamber measurements in a total area of around 1.8 hectares. Including proportions of the surface area where no chamber measurements were conducted, we estimated a potential uncertainty in ecosystem CH 4 fluxes introduced by the classification of the surface area. This potential uncertainty ranged from 14.2 mg¨m´2¨day´1 to 26.8 mg¨m´2¨day´1. Our results show that a simple classification with only few classes potentially leads to pronounced bias in total ecosystem CH 4 fluxes when plot-scale fluxes are up-scaled.

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