Figure 4: The significant drivers of alien species richness at
the small (1 x 1 m) and large (3 x 3 m) grain, and the difference in
alien species richness (Alien Δ9-1) between large and
small grain. a . Elevation, b . Northness, c .
Presence/absence of Azorella selago (the boxplots show the median
and minimum/maximum values, different letters above plots indicate
significant differences in mean values between presence and absence ofA. selago at p ≤ 0.05), d . Distance to nearest drainage,e . Geology (different letters above plots indicate significant
differences in mean values between the geologies at p ≤ 0.05), andf . Mean temperature. The graphs show the effect of predictors
on the response variable after the effect of all the other predictor
variables had been considered. Model parameters are shown in Table 1c,
d.