2.5. Statistical analyses

Statistical analyses were done in R (R Core Team, 2018) and data were processed using the openxlsx (Walker, 2019) and plyr (Wickham, 2011) packages. Figures were made with the ggplot (ggplot2 package; Wickham, 2016) and plot_grid functions (cowplot package; Wilke, 2019).

The design of all experiments allowed for pairwise statistics because identical tree–soil systems (n = 5) were measured in darkness and thereafter again under light conditions. To avoid a systematic error, the order of light and dark measurements was switched from each measurement day to the other. Differences in N₂O fluxes between treatments or diurnal and nocturnal periods (Day‐Night test) were calculated using the Wilcoxon test for paired samples (paired = T, alternative = “greater”). Differences were regarded significant for p ≤ .05.

For the Day‐Night test, the relationship between N₂O fluxes and WFPS was tested using linear regression (lm function from the stats package).