The N = 25 countries included in the analyses with environmental variables and species richness.

Environmental variables: area (in 103 km2, islands excluded), averages of net primary productivity (NPP; in kg C per m2 per year) and annual mean temperature (T; in °C), annual rainfall (R; in mm) and minimal potential evapotranspiration (PETmin; in mm), and the spatial heterogeneity in primary productivity (NPPrange), annual mean temperature (Trange), annual rainfall (Rrange), minimal potential evapotranspiration (PETminrange). Species richness for spiders (Sa), beetles (Sc), bugs (Sh), ants (Sf), herbivores (Sher) and carnivores (Scar).