Spatial variability of CH 4 fluxes measured with manual chambers at typical, well-drained tundra and boreal land cover types. Boxplots show median (thick, black line), upper and lower quartile (boxes), the highest and lowest values (black vertical lines) and all measured values (circles). Numbers indicate count of replicate collars ( N ). Negative values denote CH 4 uptake. Fluxes were measured in mid to late summer at all sites, except at Havikpak Creek, where fluxes were measured in early summer (Supplementary Table 2 ). Statistically significant differences (two-tailed) are indicated by letters, where different letters show differences at P 0.05 (land cover type, Dunn’s test, adjusted P values; vegetation type, Welch’s two-sample t -test). Exact P values for the differences between lichen and shrub are, from left to right, 0.031, ND, 0.391, 0.564, 0.251, 0.047, 0.257, 0.754. ND, not determined.
