The colours are mapped along the two axes representing the absolute changes in θ crit ( y axis) and relative changes in potential transpiration rate (Δ T pot , x axis), respectively. Each pixel is mapped continuously in its opacity, from transparency (0% change) to full intensity (99% of all observations), while the colours change continuously from sand (red) to clay (yellow) based on the soil-texture-specific relationship between Δ T pot and Δ θ crit (the colours stem from the 12 different soil textural classes; compare also the different slopes, for example, clay versus sand, to Fig. 1c ). Warm colours (red–orange–yellow) indicate an increase (+Δ θ crit ) and cold colours (blue–green) indicate a decrease (−Δ θ crit ) in critical soil moisture thresholds.
