Diversity of beetle species and functional traits along gradients of deadwood suggests weak environmental filtering

Background: Gradients in local environmental characteristics may favour the abundance of species with particular traits, while other species decline, or favour species with different traits at the same time, without an increase in average species abundances. Therefore, we asked: do variations in species and traits differ along gradients of deadwood variables? Do species abundance and trait occurrence change with species richness within or between functional groups? Thus, we analysed the beetle assemblages of five forest sites located in Italy, along the Apennines mountains.Methods: From 2012 to 2018 we sampled beetles and five deadwood types in 193 plots to characterise the deadwood gradient: standing dead trees, snags, dead downed trees, coarse woody debris, and stumps. We modelled beetle species relative abundances and trophic traits occurrences against the deadwood variables using joint species distribution models.Results: Out of 462 species, only 77 showed significant responses to at least one deadwood type, with a weak mean response across species. Trophic groups showed mostly negative responses to deadwood variables. Species abundance increased with species richness among sites only for phytophagous and saproxylophagous. Trait occurrence did not increase with species richness among sites, except for phytophagous and saproxylophagous.However, trait occurrence changed significantly with species richness of several trophic groups within some sites.We found that increases in species richness do not result in decreases in species abundance of a given trophic group, but rather null or positive relationships were found suggesting low interspecific competition.Conclusions: Our findings suggest that in Mediterranean mountain forests there is still room for increasing the level of naturalness, at least for what concerns deadwood management. On one side, our findings suggest that competition for deadwood substrates is still low, on the other side they indicate that increasing deadwood volume and types to improve overall beetle richness may increase also beetle abundances.

The identification of wildlife-vehicle collision hotspots: Citizen science reveals spatial and temporal patterns

Linear infrastructures(e.g.,roads,railways,pipelines,and powerlines)pose a serious threat to wildlife,due to the risk of wildlife-vehicle collisions(roadkills).The placement of mitigation measures,such as crossing structures,should consider species’life cycles and ecological requirements.Such an assessment would require data collection over large areas,which may be possible by employing citizen science.In this study,we aimed to identify spatiotemporal trends of roadkill occurrence using citizen science data from one of the most urbanized and biodiversityrich regions of Italy.Temporal trends were analyzed using generalized additive models,while landscape patterns were assessed by identifying significant thresholds over land cover gradients,related to increases in relative roadkill abundance,by employing threshold indicator taxa analysis.Our approach recorded a total of 529 roadkills,including 33 different species,comprising 13 mammal,10 bird,6 reptile,and 2 amphibian species.Statistical analysis indicated significant temporal trends for the red fox,the European hedgehog,the stone marten and the European badger,with peaks in roadkill occurrence between the winter and spring months.Relative roadkill abundance increased mostly in landscapes with anthropogenic land cover classes,such as complex cultivations,orchards,or urban surfaces.Our results allowed us to develop a map of potential roadkill risk that could assist in planning the placement of mitigation measures.Citizen science contributions from highly populated areas allowed data collection over a large area and a dense road network,and also directly led to the evaluation of management decisional options.