The reason for the result that the species composition in pitfall traps were more similar than for window traps between trees is probably due to that the wood becomes more similar between the tree species when they get older. The more differences in window traps might be due to different fungi outside the trees.

Quercus robur is considered to be the most species-rich tree genera and generally species-rich tree genera also have the largest numbers of specific species. However, in this study all the four tree species had some monophagus (specific) species associated. About one third of the species in this study seem to be oak-specialists. Other broad-leaved trees are important to consider in models as supporting habitats for oaks. However, the other broad-leaved tree species decay faster than the oak and therefore serves as support during a shorter time. Though, an older hollow broad-leaved tree should be considered more attention for saving than an young oak. To be able to save the whole fauna of saproxylic beetles, trees of all different tree species are needed.