Beta diversity patterns of saproxylic beetle communities in Patagonian temperate forests reflect the influence of wood decay and environmental variability on the foraging preferences of woodpeckers.

Although woodpeckers prefer trees with higher beetle diversity, the composition of beetle assemblages in the trees utilized for foraging remains largely unknown. Environmental conditions and wood decay may influence the beta diversity of saproxylic beetles, potentially affecting the woodpecker's capacity to distinguish suitable foraging substrates. We assessed the patterns of beta diversity of saproxylic beetles in live trees used and not used by Magellanic woodpeckers for foraging in Patagonian temperate forests. The additive and interactive effects of wood decay and environmental conditions on beta diversity components (total diversity, species turnover, and nestedness) across different beetle guilds (all species, predators, mycophages, and wood borers) were tested. The composition of all beetle species and wood borers in foraging trees was taxonomically distinct from those found in control trees. As the wood decay gradient increased between the foraging and control trees, the nestedness of predators and mycophages also increased. The same pattern was observed for the turnover of wood borer species. Beta diversity exhibited a positive association with continuous canopy cover; however, environmental variables modulated the effects of wood decay. Increased temperatures weakened the positive responses of wood-borer species turnover and predator nestedness to wood decay. However, the impact of wood decay on the nestedness of predators was less pronounced in certain unsuitable conditions. Although total beta diversity increased as the habitat became more suitable for beetles and woodpeckers, rising temperatures in this region may cause woodpeckers to select live trees with prey communities that are less diverse than expected.