Extended Data Fig. 5: Relative importance of a wide range of abiotic variables on methane fluxes at Trail Valley Creek.
From: Arctic soil methane sink increases with drier conditions and higher ecosystem respiration
Relative importance of abiotic variables on hourly measured methane fluxes determined with a Random Forest (RF) model for lichen, shrub, and tussock sites measured with automated chambers at Trail Valley Creek. The RF analysis was performed with data collected during year 2021 (20 531 observations) with a larger set of measured abiotic variables compared to Fig. 3 (see Supplementary Table 7 for details). The RF model for all vegetation types (18 chambers) includes only CH4 uptake, whereas for the individual vegetation types (6 chambers per vegetation type), all fluxes were included, meaning mainly CH4 uptake for lichen and shrub, but occasional emissions from tussock. Variables are grouped from top to bottom into ‘moisture-related’, ‘temperature-related’, ‘PAR-related’, and ‘other meteorological variables’, and the three most important variables are indicated by vertical dashed lines. Note that ‘PAR chamber’ denotes measurements in opaque and transparent chambers (PAR set to 0 µmol m−2 s−1 in opaque chambers), whereas ‘PAR met station’ the nearby weather station are actual site PAR data. WFPS = soil water-filled pore space, VPD = vapour pressure deficit, O2 = oxygen, TAir = air temperature, TSoil (surface) = surface soil temperature, measured at the soil surface below the vegetation or lichen layer.
