Interacting effects of forest stratum, edge and tree diversity on beetles

The richness of forest and saproxylic beetles peaked in the canopy, whereas habitat generalists and non-saproxylic beetles strongly dominated the understory. Pathways driving beetle species richness differed across forest strata. Structural equation modelling showed that tree diversity (+, positive effect) and overall dead wood volume (+) were the most important factors driving beetle species richness in the canopy. In contrast, tree diversity effects (+) were less strong and canopy openness (+) and distance from the forest edge (−) were more important in the understory.