Figure 1.

Significant paths of indirect and direct effects of tree species richness on multi-trophic interactions, estimated by the most-parsimonious structural equation model, see electronic supplementary material, table S4 for coefficients. Species richness (SR) in the lowest level (log₂ of planted tree species richness) affected primary consumer (Hemiptera) abundance and species richness, at the intermediate level. Hemiptera interacting in mutualistic trophobioses with ants (highest level), affected abundance and species richness of their partners. Arrows represent significant paths with positive correlation coefficients (p < 0.05; standardized path coefficients are given next to arrows); amount of variance explained by the model is given as the marginal coefficient of determination ($R_m^2$, based on variance of fixed effects). Absent paths are validated by non-significant difference of Fisher's C compared to a χ² distribution (n = 30, Fisher's C = 2.33, d.f. = 2, p = 0.312). (Online version in colour.)