Edge Effects in the Distribution of Coleoptera in the Forests of the Center of the European Part of Russia

SIMPLE SUMMARY: Forest edges significantly influence the distribution of many beetles. In 2020–2022, in the Republic of Mordovia (Russia), we used beer traps to collect beetles in four sites, located on the forest edges, and in forest interiors. Eight traps were on each site (edge–below, edge–above, forest interior–below, and forest interior–above) with two traps per plot. The traps were located at heights of 1.5 (below) and 7.5 m (above) above the ground. More than 13,000 specimens from 35 families were recorded. There were 13 species common to all plots, including four (Protaetia marmorata, Cryptarcha strigata, Glischrochilus grandis, and Soronia grisea) in all traps. The general pattern was the highest beetle diversity on the forest edge in the lower traps, while the total number of all species on the edges was lower. At the edges, the Shannon index was almost always higher or equal to similar values in traps in the forest interior. Based on our data, the number of saproxylic beetles prevails inside forest areas, and the highest number of them was found in the upper traps. In all plots, we found a relatively higher number of anthophilic beetles at the forest edge in the upper traps. ABSTRACT: Forest edges, which are ecotones, have a significant impact on the spatial distribution of many Coleoptera species. This research was carried out in 2020–2022 on the territory of the Republic of Mordovia (the center of the European part of Russia). Beer traps (with a bait made of beer with sugar) were used to collect Coleoptera. Four plots were selected for the research, which differed in the composition of plants on the edges, adjacent open ecosystems, and types of forest ecosystems. The forest adjoined closely to this open ecosystem. Inside the forest interior, at 300–350 m, a control inner section of the forest with a closed canopy was selected. There were eight traps on each site: edge–below, edge–above, forest interior–below, and forest interior–above, with two traps in each plot. These traps were located at a height of 1.5 (below) and 7.5 m (above) above the ground on tree branches. In total, more than 13,000 specimens from 35 families were recorded. Cerambycidae, Nitidulidae, Curculionidae, and Elateridae had the greatest species diversity. Nitidulidae (71.6% of all individuals), Curculionidae (8.3%), Scarabaeidae (7.7%), and Cerambycidae (2.4%) predominated in total number. There were 13 species common to all plots. At the same time, only four species were found in all traps (Protaetia marmorata, Cryptarcha strigata, Glischrochilus grandis, and Soronia grisea). The abundance of P. marmorata on all plots at an altitude of 7.5 m on the edges was greater. G. grandis prevailed in the lower traps. The abundance of C. strigata and S. grisea varied depending on the location of the trap on different plots. The general pattern was the greatest species diversity of Coleoptera on the edges in the lower traps. At the same time, the total number of all species on the edges was lower. At the edges, the Shannon index was practically always higher or equal to similar indicators in traps located in the forest interior. According to the average values of all plots, it turned out that the number of species of saproxylic Coleoptera prevails inside forest areas, and the largest number of saproxiles was found in the upper traps. An interesting feature for all plots was a more significant relative number of anthophilic species at the edge in the upper traps.