Figure 1.

Schematic of one block in the experimental design, showing the ant treatments as whole plots, the three levels of specific diversity as split-plots, and the three different mono-, di- and tri-specific combinations of the three focal pine species. Constructing three different tri-specific combinations was possible by including a fourth native pine species (P. pinea, circles with bars). Including ‘combination’ as a factor in the model allowed us to remove the possible effects of considering particular species (i.e. sampling effects), thus testing for non-additive effects of diversity. In the field, diversity combinations were randomized within the whole plots (not showed here for clarity).