Effects of invasion (control vs. invaded) and cover of Gaillardia aristata on species richness, Shannon diversity (with and without G. aristata) and the height of local vegetation. Box plots show medians, lower and upper quartiles, notches show 95% confidence intervals. Grey × symbols represent sampling plots. Significant differences (after p-value adjustment) between the invaded and control sites are indicated by star (*) above the boxes and the significant effect of invasion cover by continuous lines according to the GLMMs (see Suppl. material 2).