Data from: Small birches matter: Beetle diversity on burned birch and pine in boreal forests
Data files
Aug 05, 2026 version files 199.47 KB
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ModelData.csv
16.98 KB
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README.md
4.70 KB
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Speciesdata.csv
177.78 KB
Abstract
Forest fires create substrates critical for saproxylic and fire-favoured species, but fire suppression has led to a reduction of these substrates, contributing to declines in the associated beetle populations. While beetle responses to fire have been commonly studied in pine-dominated (Pinus sylvestris) forests, much less is known about how burned birch (Betula pendula/pubescens), another fire-favoured tree species, supports beetle communities. We compared beetle community dissimilarities between prescribed-burned birch and pine in boreal forests of Sweden, 0-2 years post-fire.
Using data after sampling beetles with trunk-attached traps, we analysed beetle species richness, abundance and species assemblage on 60 birches and 60 pines of varying diameters. We also used each tree's vitality and char height as proxies for fire severity. The results showed that birches had higher beetle species richness than pines and distinct beetle community composition, driven by its higher mortality post-fire, whereas the number of red-listed species was higher on pines. Neither species richness nor abundance were related to tree diameter. Beetle abundance on birch increased with char height of the trunk, whereas species richness decreased, suggesting an increase in specialized species. Our findings indicate that birch, even with small diameters, contributes to the conservation of saproxylic and pyrophilous beetle diversity following prescribed burning.
Dataset DOI: 10.5061/dryad.gqnk98t49
Description of the data and file structure
Beetle sampling and trap tree measurements
The selected trees were used as beetle trap trees. Beetles were sampled with small trunk-attached flight interception traps, following (Bergmark et al. 2024). According to their study, beetle communities sampled with these small window traps are very distinct and can be used to investigate the beetle fauna of individual trees. The traps were built using Plexiglas, a 1000 ml tub directly underneath, attached vertically at breast height onto the trunk of the trap trees, directed southwards to standardize possible sun exposure. A mixture of 60 percent Propylene glycol, water, and a small amount of detergent was poured into the traps to kill and preserve any organisms until emptying. All traps were placed during late May- early June 2024 and emptied once during July and once during late August, covering the most active period of insect activity. The two sampling occasions were then pooled together for each trap. One of the forest areas (see Figure 1) was burned at the beginning of June 2024, and the traps were placed on trees the day after the fire. All beetles (Coleoptera) were morphologically identified to species level by a taxonomic expert, Dr. Petri Martikainen. The nomenclature follows Dyntaxa (SLU Artdatabanken, 2026). Red-listed species were classified according to the Swedish Red List 2020 (Eide et al. 2020) and pyrophilous species according to Wikars (2006). After identification, all specimens are being preserved in ethanol and kept at the Swedish University of Agricultural Sciences in Umeå (AMH).
The height, diameter at breast height, and species of each trap tree was registered. Fire severity was estimated by measuring the visible char height of the trunk in cm. Vitality was estimated visually by presence/absence and colour of leaves or needles: green leaves or needles were considered alive, partly yellowing leaves or needles as reduced vitality, and no leaves or needles or completely yellow as dead.
Files and variables
File: ModelData.csv
Description: Dataframe used as input variables for modeling.
Variables
- Plot_ID: Each unique plot, containing two pines and two birches
- ID: Each unique trap, on each unique tree
- SPTotal_Abundance: Abundance of beetle individuals in each unique trap
- SPSpecies_Richness: Number of species in each unique trap
- TreeSpecies: Species of the tree (pine/birch)
- Tree_dbh_cm: Diameter of the tree
- Year: One of three stands within which plots (Plot_ID) are located. This also signifies one of three years of burning (2022/2023/2024)
- Treatment_id: Synonymous with Year, but denotes prescribed burning and year (eg PB22 denotes prescribed burning 2022)
- Tree_height_m: Height of each unique tree sampled.
- Date And Time: Sample collection date in the format month-day-year, e.g., 5-28-2024 meaning the 28th of may year 2024.
- Plot_tree_id: A unique ID for each unique tree sampled, and combined with the treatment ID.
- Vitality: The vitality of the tree sampled (Alive/Reduced/Dead)
- flame_height_m: The height of the visible charring (in the manuscript called char height)
- Tree_plot_id: Letters denoting pines (C/D) and birches (A/B) in each plot, for combination into plot_tree_id
- Treatment: Only denotes prescribed burning
- Date: self-explanatory
- Pyrophilous_Species_Richness: Number of pyrophilous beetle species on each unique tree (as per Wikars 2006).
- Pyrophilous_Abundance: Number of pyrophilous beetle individuals on each unique tree
- Redlisted_Species_Richness: Number of red-listed beetle species on each unique tree (as per the red list 2020)
- Redlisted_Abundance: Number of red-listed beetle individuals on each unique tree
File: Speciesdata.csv
Description: Dataframe containing detailed information of beetle species found on each unique tree sampled.
Variables
- ID: Each unique trap, on each unique tree
- year: One of three stands within which plots (Plot_ID) are located. This also signifies one of three years of burning (2022/2023/2024)
- Plot_ID: Each unique plot, containing two pines and two birches
- order: Taxonomic order of the beetle species
- family: Taxonomic family of the beetle species
- genus: Taxonomic genus of the beetle species
- species: Beetle species
- abundance: Number of individuals
- taxon_id: Taxonomic ID number of the beetle species
- red_list_2020: Category of red listing for the beetle species (as per the Red List 2020).
The selected trees were used as beetle trap trees. Beetles were sampled with small trunk-attached flight interception traps, following (Bergmark et al. 2024). According to their study, beetle communities sampled with these small window traps are very distinct and can be used to investigate the beetle fauna of individual trees. The traps were built using Plexiglas, a 1000 ml tub directly underneath, attached vertically at breast height onto the trunk of the trap trees, directed southwards to standardize possible sun exposure. A mixture of 60 percent Propylene glycol, water, and a small amount of detergent was poured into the traps to kill and preserve any organisms until emptying. All traps were placed during late May- early June 2024 and emptied once during July and once during late August, covering the most active period of insect activity. The two sampling occasions were then pooled together for each trap. One of the forest areas (see Figure 1) was burned at the beginning of June 2024, and the traps were placed on trees the day after the fire. All beetles (Coleoptera) were morphologically identified to species level by a taxonomic expert, Dr. Petri Martikainen. The nomenclature follows Dyntaxa (SLU Artdatabanken, 2026). Red-listed species were classified according to the Swedish Red List 2020 (Eide et al. 2020) and pyrophilous species according to Wikars (2006). After identification, all specimens are being preserved in ethanol and kept at the Swedish University of Agricultural Sciences in Umeå (AMH).
The height, diameter at breast height, and species of each trap tree was registered. Fire severity was estimated by measuring the visible char height of the trunk in cm. Vitality was estimated visually by presence/absence and colour of leaves or needles: green leaves or needles were considered alive, partly yellowing leaves or needles as reduced vitality, and no leaves or needles or completely yellow as dead.