Figure 4.

The effect of host plant species diversity (mono-, di- and tricultures) and the presence of mutualistic ants (two levels: presence or absence) on the concentration of (a) total phenolics, (b) non-volatile resin, (c) soluble sugars and (d) starch in the stem of the pine trees. Ant treatments were in place for four months. Initial height was used as covariate in the statistical analyses. Least-square means ± s.e. (n = 72). Results of the mixed model are shown in the figure, where asterisks indicate significant differences (p < 0.05). A × D, ant × diversity interaction.