DOI: 10.5061/dryad.zcrjdfnpj
title: Sun exposure as a key factor influencing saproxylic beetle communities

description: The ability to locate and colonize ephemeral deadwood resources is crucial
 to saproxylic beetle assemblages. Saproxylic beetles locate suitable
 substrates mainly through visual cues and via olfactory cues emitted by
 deadwood, other insects and, wood-decaying fungi. For the conservation of
 saproxylic beetles, it is essential to understand which abiotic factors
 and biotic interactions most significantly influence their habitat
 requirements when locating suitable substrates. In a field
 experiment, in sunny and shaded plots, we exposed 400 bundles of freshly
 cut deadwood, each consisting of three logs with a combination of
 different tree species and treatments (i.e., fungi inoculation), mimicking
 biotic interactions. We sampled arriving saproxylic beetles via sticky
 traps directly applied on the deadwood substrate to evaluate the effect of
 sun exposure and the biotic interactions on colonizing saproxylic
 beetles. We found higher species numbers and an abundance of
 saproxylic beetles under shaded than sunny conditions, but there was no
 effect on the standardized number of species (diversity). However, we
 observed a shift in species diversity from sunny to shaded conditions from
 early to late season. Beetle assemblages differ between shaded and
 sun-exposed deadwood. Treatments (fungi inoculation, sterilization, and
 burning) did not affect saproxylic beetle colonization.  Our
 results suggest that colonization of freshly cut deadwood by saproxylic
 beetles is mainly driven by sun exposure rather than biotic interactions,
 despite assumed close associations between beetles and fungi. To protect
 the full spectrum of saproxylic beetle species, we recommend managing both
 sunny and shaded areas, as each provides unique habitats that support
 different species compositions.
description: # **Sun exposure as a key factor influencing saproxylic beetle
 communities**
 [https://doi.org/10.5061/dryad.zcrjdfnpj](https://doi.org/10.5061/dryad.zcrjdfnpj) ## Description of the data and file structure This dataset provides the data and codes to explore the attraction of saproxylic beetles to freshly cut logs exposed to abiotic conditions (sun exposure levels) and biotic conditions (fungi inoculations of the logs). Ten sites in Central Europe were selected, spread across different forest structures and altitudes from 300 to 1000 m.a.s.l. In each site, we establish a plot in the forest, looking for as many shading conditions as possible, and one plot at the margins of the forest, exposed to sunlight. This setup allowed us to test for the effect of sun exposure on the diversity and composition of saproxylic beetle assemblages. In each plot, 20 bundles (3 logs) were hung on a pole with a different combination of tree species (Oak, Beech, Spruce, Pine) and treatments (Brown-rot inoculated, White-rot inoculated, Burned, Sterilized, and Control). To study the preference of beetles towards different levels of exposure and treatments, we applied sticky traps on the top of each bundle. This allowed us to study the attraction of saproxylic beetles towards treated logs and/or different sun exposure levels.  ### Files and variables #### Data #### File: env\_final.rds **Description:** Contain environmental variables to analyze the data in a ".rds" format to preserve factors and numerical variables. • code *(chr)*: Unique sampling unit identifier. • tree_species *(factor, levels = 4)*: Tree species used in the experimental study. Includes two broadleaf species (Oak, Beech) and two conifer species (Pine, Spruce). • treatment *(factor, levels = 5)*: Treatments applied to logs to study beetle attraction: 1\. **Control**: Logs without fungal inoculation or other treatments. 2\. **White-rot**: Logs inoculated with white-rot fungi. 3\. **Brown-rot**: Logs inoculated with brown-rot fungi. 4\. **Burned**: Logs subjected to a burning treatment. 5\. **Sterilized**: Logs sterilized to eliminate fungi and other microorganisms. • locality *(factor, levels = 10)*: Study site locations. • exposure *(factor, levels = 2)*: Sunlight exposure levels: • **Shady**: Within the forest, shaded plots. • **Exposed**: At the forest margins, fully exposed to sunlight. • altitude *(num)*: Altitude of the site in meters above sea level (m.a.s.l.). • tree *(factor, levels = 2)*: Tree type based on leaf structure: • **Broadleaf**: Includes Oak and Beech. • **Coniferous**: Includes Pine and Spruce. • run *(factor, levels = 2)*: Sampling run identifier: • **1**: First sampling (Early season). • **2**: Second sampling (Late season). • time_exp *(num)*: How many days a sticky traps remained on the bundle. • nspec *(num)*: Number of beetle species recorded per sampling unit. • abu *(num)*: Total abundance of beetles recorded per sampling unit. #### File: stickies\_final.csv **Description:** This file contains a community matrix representing pooled saproxylic beetle data collected during two sampling runs. The matrix has **800 rows** (sampling units) and **198 columns** (beetle species). Each entry indicates the abundance of a specific beetle species captured in a given sampling unit. #### File: 01\_Models.R Description: This R script contains the code used for analyzing saproxylic beetle assemblages, focusing on diversity metrics based on the Hill framework and conducting indicator species analysis. #### File: 02\_Figures.R Description: This R script contains code for generating figures used in the analysis of saproxylic beetle assemblages for the present study. **Code/software** All statistical analyses and data visualizations were performed using **RStudio**, a free and open-source Integrated Development Environment (IDE) for R. The packages, listed in the attached R scripts, were used in the analyses, along with their respective versions as of the latest update (29-11-2024):