1. The enrichment of deadwood is essential for the conservation of saproxylic biodiversity in managed forests. However, existing strategies focus on a cost-intensive increase of deadwood amount, while largely neglecting increasing deadwood diversity.
2. Deadwood objects, i.e. logs and branches, from six tree species were experimentally sun-exposed, canopy-shaded, and artificially shaded for four years, after which the alpha-, beta-, and gamma-diversity of saproxylic beetles, wood-inhabiting fungi, and spiders were analyzed. Analyses of beta-diversity included the spatial distance between exposed deadwood objects. A random-drawing procedure was used to identify the combination of tree species and sun exposure that yielded the highest gamma-diversity at a minimum of exposed deadwood amount.
3. In sun-exposed plots, species numbers in logs were higher than in shaded plots for all taxa, while in branches we observed the opposite for saproxylic beetles. Tree species affected the species numbers only of saproxylic beetles and wood-inhabiting fungi. The beta-diversity of saproxylic beetles and wood-inhabiting-fungi among logs was influenced by sun exposure and tree species, but beta-diversity of spiders by sun exposure only. For all saproxylic taxa recorded in logs, differences between communities increased with increasing spatial distance.
4. A combination of canopy-shaded Carpinus logs and sun-exposed Populus logs resulted in the highest species numbers of all investigated saproxylic taxa among all possible combinations of tree species and sun-exposure treatments.
5. Synthesis and applications. We recommend incorporating the enrichment of different tree species and particularly the variation in sun exposure into existing strategies of deadwood enrichment. Based on the results of our study, we suggest to combine logs of softwood broadleaf tree species (e.g. Carpinus, Populus), hardwood broadleaf tree species (e.g. Quercus) and coniferous tree species (e.g. Pinus) under different conditions of sun exposure and distribute them spatially in a landscape to maximize the beneficial effects on overall diversity.