Post-Fire Coleoptera Fauna in Central Russian Forests after the 2021 Fires (Study Using Beer Traps)

Simple Summary This study presents an analysis of the Coleoptera fauna in the forests of the Euro-pean Russia in 2022 and 2023, after a fire. Insects were sampled from burned plots (9) in 2010 and 2021, as well as unburned (control) plots (2), and alpha diversity was compared. After processing the material, we examined a total of 12,218 Coleoptera specimens from 38 families and identified 194 species. The families Nitidulidae, Cerambycidae, Elateridae, and Scarabaeidae were the most abundant across all plots. Cerambycidae, Elateridae, Nitidulidae, Staphylinidae, Coccinellidae, and Scarabaeidae exhibited the greatest species diversity. In total, 17 species were found on all plots. Only five species exhibited preferences for some certain plots. Maximum abundance and species diversity were observed on unburned (control) plots. The plots where fires occurred in 2010 and 2021 had the lowest total abundance values for Coleoptera. These fires destroyed almost all potential sites for beetle settlement, feeding, breeding, and shelter. Abstract Fires can significantly impact forest ecosystems. However, studies on the effects of fires on insect communities in post-fire plots in natural forests are rare. This study presents an analysis of the Coleoptera fauna in the forests of the Mordovia State Nature Reserve (European Russia) in 2022 and 2023 after a fire. Insects were sampled from burned plots (9) in 2010 and 2021, as well as unburned (control) plots (2), and alpha diversity was compared. After processing the material, we examined a total of 12,218 Coleoptera specimens from 38 families and identified 194 species. The families Nitidulidae, Cerambycidae, Elateridae, and Scarabaeidae were the most abundant across all plots. Cerambycidae, Elateridae, Nitidulidae, Staphylinidae, Coccinellidae, and Scarabaeidae exhibited the greatest species diversity. In total, 17 species were found on all plots, including Cetonia aurata, Protaetia cuprea volhyniensis, Trogoderma glabrum, Carpophilus hemipterus, Epuraea biguttata, Glischrochilus grandis, Glischrochilus hortensis, Glischrochilus quadripunctatus, Soronia grisea, Pediacus depressus, Chrysanthia geniculata, Anastrangalia reyi, Leptura quadrifasciata, Leptura thoracica, Lepturalia nigripes, Rhagium mordax, and Anisandrus dispar. Only five species exhibited preferences for certain plots. Maximum abundance and species diversity were observed on unburned (control) plots. The plots where fires occurred in 2010 and 2021 had the lowest total abundance values for Coleoptera. These fires destroyed almost all potential sites for beetle settlement, feeding, breeding, and shelter. Traps recorded a higher abundance of Coleoptera in the first year after fires compared to the second year. The Coleoptera fauna showed the greatest similarity on the control plots.


Introduction
In forest ecosystems, Coleoptera are a significant community component that plays a crucial role in substance cycling and redistribution, organic matter decomposition, pollination, and biological control [1][2][3][4][5].Most publications that discuss the effects of wildfires Insects 2024, 15, 420 3 of 20 part of the reserve.The soils in this area are predominantly sandy, with varying degrees of podzolization.The average annual precipitation ranges from 406.6 to 681.3 mm, while the average annual air temperature is 4.7 • C. Maximum values are recorded in July (+39-40 • C) and minimum values in February (−42-45 • C) [30].

Sampling Procedures
Material was collected between April and October using beer traps baited with beer and sugar.Each trap was made from a 5 L plastic container that previously contained water.A 10 × 10 cm square hole was cut out on one side of the container.It is necessary for the arrival of beetles.Bait made of beer and sugar was poured into the bottom of the container [32].One trap was set per plot, with the trap set at a height of 1.5 m, hanging below a small wooden tripod [33].Traps were checked depending on weather conditions after 7-14 days.At the same time, after each check, all the bait was poured out and a completely new bait was added.Material was sampled 13 times in 2022 and 15 times in 2023 and then summarized.A total of 11 plots were selected for the study (Figure 1).These plots varied in terms of fire intensity, distance from the fire edge, and degree of vegetation recovery following the 2010 fires.Previously, Ruchin [31] published detailed descriptions and photos of all plots.We sampled plots that burned in 2010 and 2021 (plots 3, 4, 5, 6, 7, and 9), plots that burned only in 2010 (plots 1, 2, and 8), and control plots (plots 10 and 11) that never burned.A brief comparative description of plots is provided in Table 1.
area was a pine (Pinus sylvestris L.), which formed pure or mixed forest communities.However, due to the 2010 fires, many pine forests were replaced by birch (Betula pendula Roth), resulting in deformations.The Mordovia State Nature Reserve contains pure forest communities of linden (Tilia cordata Mill.) in the northern region.Oak forests (Quercus robur L.) are found in smaller areas, mainly in the floodplain of the Moksha River in the western part of the reserve.The soils in this area are predominantly sandy, with varying degrees of podzolization.The average annual precipitation ranges from 406.6 to 681.3 mm, while the average annual air temperature is 4.7 °C.Maximum values are recorded in July (+39-40 °C) and minimum values in February (−42-45 °C) [30].

Sampling Procedures
Material was collected between April and October using beer traps baited with beer and sugar.Each trap was made from a 5 L plastic container that previously contained water.A 10 × 10 cm square hole was cut out on one side of the container.It is necessary for the arrival of beetles.Bait made of beer and sugar was poured into the bottom of the container [32].One trap was set per plot, with the trap set at a height of 1.5 m, hanging below a small wooden tripod [33].Traps were checked depending on weather conditions after 7-14 days.At the same time, after each check, all the bait was poured out and a completely new bait was added.Material was sampled 13 times in 2022 and 15 times in 2023 and then summarized.A total of 11 plots were selected for the study (Figure 1).These plots varied in terms of fire intensity, distance from the fire edge, and degree of vegetation recovery following the 2010 fires.Previously, Ruchin [31] published detailed descriptions and photos of all plots.We sampled plots that burned in 2010 and 2021 (plots 3, 4, 5, 6, 7, and 9), plots that burned only in 2010 (plots 1, 2, and 8), and control plots (plots 10 and 11) that never burned.A brief comparative description of plots is provided in Table 1.It is located 10 m from the edge of the fire deep into the burnt territory (20 m from plot 8).The deadwood, birch, shrubs, and grassy tier were partially burned out.At least half of the dead wood and a lot of dense dry birch undergrowth remained.2010 It is located 10 m from the edge of the fire in 2021.A significant amount of large deadwood trees (pine and birch).Very dense undergrowth of birch and aspen.The grassy tier is sparse.
The litter from the fall of hardwoods is small.2010 and 2021 It is located 10 m from the edge of the fire deep into the burnt territory (20 m from plot 10).The deadwood, birch, shrubs, and grassy tier were partially burned out.At least half of the dead wood and dense dry birch undergrowth remain.

Not burned (control)
A plot of forest that has not been exposed to fire.It is located 10 m from the edge of the fires of 2010 and 2021.Old mixed forest of Pinus sylvestris, Betula with an admixture of Tilia cordata, Sorbus aucuparia (in the second tier).The litter is well-defined and powerful, and the grassy layer is sparse.
11 Not burned (control) It is located 500 m from the edge of the fires.The old mixed forest is similar in configuration to plot 10.The litter is well-defined and powerful, and the grassy layer is sparse.

Data Analyzes
The Jaccard index was used for comparison based on all beetle species identified on different plots.Additionally, we calculated the Margalef, Shannon, and Simpson indexes [46][47][48] to understand species diversity and community equitability.In our calculations, we excluded Coleoptera that were not identified at the species level.Jaccard index similarity is presented as a dendrogram built using Ward's method and Ecuclidian distance.We determined saproxylic species based on guidelines from publications [49][50][51][52] and our own data [53].Anthophilous species were defined as those that repeatedly visited flowers.Our own long-term observations, as well as information from publications [33,54], were used in this case.For saproxylic and anthophilic species, calculations were made for the ratio of the number of these species to the total number of species in a particular plot and expressed as a percentage.
Statistical analysis was performed with PAST 4.07 [55].The ordination techniques, using principal component analysis (PCA), defined the main gradients in the distribution of the studied species selected for analysis (we analyzed the species that were common to all plots).To provide an ecological interpretation of the ordination axes, studied sites based on the registered species abundance were plotted on the PCA ordination diagram as additional environmental data.
The number of Coleoptera collected in traps varied among plots.The highest abundance of Coleoptera was observed on plot 11, plot 10, plot 8, and plot 1 (Figure 2).The plots with the lowest abundance values were plot 5, plot 3, and plot 4. Variations in Coleoptera abundance were observed across different years.In 2022, plots near the 2021 fire boundary (7,8,9,10) and control plots (1,11) had the highest beetle abundance.However, on plots 4, 5, and 6, which were far away from unburned forests and experienced intensive fires, beetle abundance was higher in 2023, the second year after the 2021 fire (Figure 2).all plots).To provide an ecological interpretation of the ordination axes, studied sites based on the registered species abundance were plotted on the PCA ordination diagram as additional environmental data.
The number of Coleoptera collected in traps varied among plots.The highest abundance of Coleoptera was observed on plot 11, plot 10, plot 8, and plot 1 (Figure 2).The plots with the lowest abundance values were plot 5, plot 3, and plot 4. Variations in Coleoptera abundance were observed across different years.In 2022, plots near the 2021 fire boundary (7,8,9,10) and control plots (1,11) had the highest beetle abundance.However, on plots 4, 5, and 6, which were far away from unburned forests and experienced intensive fires, beetle abundance was higher in 2023, the second year after the 2021 fire (Figure 2).Plots 3, 4, and 5 had fewer beetle species than the rest of the plots, the latter of which ranged from 20 to 24 species each (Table 2).The diversity of Coleoptera species was highest on plots that either did not burn or burned only in 2010 in both years of the study.The Plots 3, 4, and 5 had fewer beetle species than the rest of the plots, the latter of which ranged from 20 to 24 species each (Table 2).The diversity of Coleoptera species was highest on plots that either did not burn or burned only in 2010 in both years of the study.The lowest species diversity was observed on plots that burned in both 2010 and 2021 and were located deep within these fires.The Shannon index yielded the highest value for plot 8. Overall, the burned plots from 2021 exhibited relatively high values for the Shannon index and low values for the Simpson index.The number of beetle species on these plots (4, 5, and 6) was significantly lower than on unburned plots (10 and 11), as evidenced by the low values of the Margalef index.The number of species was highest on plots 10 and 11.In contrast, plots bordering burned wood (7, 8, 9, 10, and 11) or unburned plots (10 and 11) had high Margalef index values.Meanwhile, unburned plots (10 and 11) had low Shannon index values and high Simpson index values, indicating the dominance of one or more Coleoptera species on these plots (Table 2).
The percentage of saproxylic species varied among the plots studied, ranging from 75.8% (plot 6) to 87.0% (plot 9).Plot 6 had the lowest relative number of saproxylic species, while plots 9 and 3 (located on the boundary of burned plots) had the highest values (Table 2).There was no difference observed in the dynamics of the number of saproxylic species on individual plots during the study years.The fluctuations of this parameter on all plots varied by 10%.However, the parameter underwent the least amount of change on the unburned plots (1, 8, 10, 11), while the highest limit of variation was obtained on the plots burned in 2021 (Figure 3).
The percentage of anthophilic species varied among the studied plots, ranging from 45.5% (plot 6) to 59.7% (plot 1).Plot 6 had the lowest number of anthophiles, while plot 1 had the highest (Table 2).No changes in the number of anthophilic species by years of study were recorded on different plots.Somewhat larger changes of the parameter were obtained on boundary plots (Figure 3).The percentage of anthophilic species varied among the studied plots, ranging from 45.5% (plot 6) to 59.7% (plot 1).Plot 6 had the lowest number of anthophiles, while plot 1 had the highest (Table 2).No changes in the number of anthophilic species by years of study were recorded on different plots.Somewhat larger changes of the parameter were obtained on boundary plots (Figure 3).
Out of the 194 species, 17 (8.6%)were present in all plots studied.The following are the taxa from the following seven families: Figure 4 shows that the abundance of most of the 17 species did not depend on the plots.However, five species (E.biguttata, G. grandis, G. hortensis, G. quadripunctatus, and Rh.mordax) were exceptions.The abundance of four species, namely, E. biguttata, G. grandis, G. hortensis, and G. quadripunctatus, showed substantially higher numbers on plot 10 and particularly on plot 11.This information pertains to the results of the Shannon and Simpson index calculations on plots 10 and 11 (Table 2).The calculations demonstrated the dominance of one or more Coleoptera species.For instance, Rh. mordax and these species represented the majority of individuals (67.7%) on plot 11.Meanwhile, Rh. mordax was the most abundant species on plot 10 (Figure 4). Figure 4 shows that the abundance of most of the 17 species did not depend on the plots.However, five species (E.biguttata, G. grandis, G. hortensis, G. quadripunctatus, and Rh.mordax) were exceptions.The abundance of four species, namely, E. biguttata, G. grandis, G. hortensis, and G. quadripunctatus, showed substantially higher numbers on plot 10 and particularly on plot 11.This information pertains to the results of the Shannon and Simpson index calculations on plots 10 and 11 (Table 2).The calculations demonstrated the dominance of one or more Coleoptera species.For instance, Rh. mordax and these species represented the majority of individuals (67.7%) on plot 11.Meanwhile, Rh. mordax was the most abundant species on plot 10 (Figure 4).
The Jaccard index calculation revealed significant differences between the plots (Figure 5).The biodiversity of Coleoptera on plots 10 and 11, which were not affected by fires, was similar and significantly different from all other plots.Plots 3, 4, and 5, which burned in 2021, were grouped separately, while plot 6 occupied a distinct position.The fire margins were closely related with minimal differences in species composition.1.
The Jaccard index calculation revealed significant differences between the plots (Figure 5).The biodiversity of Coleoptera on plots 10 and 11, which were not affected by fires, was similar and significantly different from all other plots.Plots 3, 4, and 5, which burned in 2021, were grouped separately, while plot 6 occupied a distinct position.The fire margins were closely related with minimal differences in species composition.

Discussion
Our study investigated the effectiveness of using beer traps at low altitudes to study Coleoptera biodiversity in burned areas.The methodology has been extensively studied in open biotopes and forest edges [33,56,57] and can be applied to analyze biodiversity,

Discussion
Our study investigated the effectiveness of using beer traps at low altitudes to study Coleoptera biodiversity in burned areas.The methodology has been extensively studied in open biotopes and forest edges [33,56,57] and can be applied to analyze biodiversity, faunal similarity, and other indicators.Our results indicate that beer traps located at low altitudes in open biotopes effectively attract Coleoptera and can profitably be used in other similar studies.The 2021 fires in the Mordovia State Nature Reserve destroyed dry trees, deadwood, and herbaceous vegetation in many areas, making the use of beer traps on tripods appropriate and effective.
The 2021 fires are considered catastrophic events due to their rapid spread over large areas during windy weather.These events can have devastating impacts on ecosystems, including the entomofauna.Such evaluations are objective and based on observable consequences.For instance, Duelli et al. [58] observed significant increases in insect species diversity and abundance in forests following windstorms.Similarly, Moretti et al. [59] and Bogusch et al. [60] found a similar effect among certain insect groups following significant fires in various European countries.However, severe fire impacts can significantly delay the recovery of insect fauna over large areas.In these cases, the entire ecosystem is disturbed, resulting in the death of plants across all forest layers, leading to a decrease in both biodiversity and abundance insects [61,62].
Small fires in disturbed forests allow more sunlight to reach the soil, promoting the growth of grasses, shrubs, and young trees.These conditions are more attractive to phytophagous, anthophilous, and other ecological groups of insects, which, in turn, become prey for predatory insects.Sunlight also promotes the reproduction and larval development of these insects on grasses, shrubs, and forest edges [14,57,63].Low-intensity fires typically result in increases in species diversity and abundance.Small fires weaken deadwood, dry trees, and stumps, leading to the development of large numbers of saproxylic Coleoptera species [64][65][66].
In 2022, the traps recorded a 37% higher abundance of Coleoptera in the year following the fires compared to the second year (2023) after the fires.It is unclear whether this result is related to the duration of the experiment, as the traps were operated for 160 days in 2022 and 181 days in 2023.The reasons for this result are likely due to both unknown meteorological factors and the observed increase in abundance of many insect species after fires.These are the typical characteristics of mixed forests in the temperate zone.Forest plots 1 and 8 experienced fires in 2010 but not in 2021.The regeneration of birch and pine is slow, and there is a significant amount of dead wood, including dry dead trees resulting from the fires.Plots 3, 4, and 5 had the lowest total abundance of Coleoptera.In addition to the fire of 2021, these suffered previous fires in 2010, which destroyed almost all deadwood, dry trees, herbaceous and shrub layers, and a young birch forest down to the roots in 2021.In the second year following the 2021 fires on plots 4, 5, and 6, there was a small increase in the number of Coleoptera species.
According to the Jacquard index the Coleoptera fauna showed the greatest similarity on plots 10 and 11, which formed a distinct clade that differed significantly from all others.Plots 1 and 2, plots 4 and 5, and plots 7 and 8 were also characterized by similar values.All of them were located close to each other or had similar conditions for beetles to live in.Plots 3, 4, and 5 also formed a distinct clade, while plot 6 was somewhat separated on the dendrogram.These results suggest that the faunas of the burned plots are similar to each other, and the beetle faunas of the control plots are more similar to one another than to the other plots.
Only 17 species of Coleoptera were found on all plots.However, the principal component analysis did not reveal any changes in the abundance of 12 out of these 17 species.That is, 12 species are quite widespread in biotopes and can inhabit both open ecosystems (burned plots) and forest ecosystems.Only five species showed certain trends in preference.For instance, E. biguttata can survive on rotting mushrooms, berries, fruits, and decaying liquids [67].Adults of G. grandis and G. hortensis are commonly found on decaying tree sap from various trees, while their larvae develop on different decaying substrates [68,69].G. quadripunctatus and Rh.mordax are commonly found in subcortical habitats of both coniferous and deciduous trees, where they feed on decaying tree sap from various tree species [70,71].
The study showed that the diversity and abundance of Coleoptera species were greater on unburned plots than on burned ones.Moreover, plots with one or more species dominance led to a decrease in the Shannon index and an increase in the Simpson index.These indicators changed inversely on plots without herbaceous vegetation, shrubs, deadwood, and dead trees.It is a well-established fact that fires on small plots promote subsequent infestation in neighboring unburned plots [61,62].However, plots with highland fires may be adjacent to plots with lowland fires.In such cases, the fauna of completely burned plots takes longer to recover [29].However, if all possible feeding objects for Coleoptera adults and larvae are completely destroyed by fire, recovery may take even longer.The relative number of saproxylic and anthophilic species varied on different plots, confirming this fact.The burned plots would be mainly colonized by saproxylic species that inhabit deadwood or remnants of dead trees.Following primary fires, these organics attract numerous saproxylic invertebrates [72,73].However, a secondary fire in 2010 destroyed the maximum possible habitats with decaying organics.As a result, there was no significant increase in saproxylic abundance.

Conclusions
We surveyed 11 plots and collected 12,218 specimens of 194 Coleoptera species from 38 families over the course of two years.The families Nitidulidae, Cerambycidae, Elateridae, and Scarabaeidae were the most abundant across all plots.Cerambycidae, Elateridae, Nitidulidae, Staphylinidae, Coccinellidae, and Scarabaeidae were the families with the greatest species diversity.All plots had 17 species in common, while only 5 species showed a preference for specific plots.The unburned (control) plots yielded the highest abundance and species diversity.Meanwhile, plots that experienced fires in 2010 and 2021 had the lowest total Coleoptera abundance values.The fire in 2021 on these plots destroyed nearly all objects that could be used for the settlement, feeding, breeding, and sheltering of beetles.In the first year after the fire of 2021, the traps recorded a higher abundance of Coleoptera than in the subsequent year.The coleopteran fauna were most similar on the control and on nearby plots.

Figure 1 . 1 .
Figure 1.Geographical position of the Mordovia State Nature Reserve in Europe.Study plots are named according to designations in the text.The red line shows the boundary of the fires of 2021 (fires Figure 1.Geographical position of the Mordovia State Nature Reserve in Europe.Study plots are named according to designations in the text.The red line shows the boundary of the fires of 2021 (fires were north of this line).Darker green areas are lower elevations and lighter green higher elevations.A brief description of the plots1-11 is given in Table1.

Figure 2 .
Figure 2. Coleoptera numbers on plots during by years of study.

Figure 2 .
Figure 2. Coleoptera numbers on plots during by years of study.

Figure 3 .
Figure 3. Percentages of saproxylic and anthophilic Coleoptera species on plots by year of study.

Figure 5 .
Figure 5.The similarity of Coleoptera species on 11 plots based on the Jaccard index.

Table 1 .
A brief description of the plots in the places of installation of traps.In 2021, not exposed to fire.Some amount of dead wood, trees (Pinus and Betula).Dense undergrowth of birch.Shrubs are mainly represented by raspberries (Rubus).In 2021, the territory was completely burned out.The deadwood and grassy tier are completely burnt out.There were rare dry bushes.It is located 10 m from the edge of the fire deep into the burnt territory (20 m from plot 2).2010 and 2021 In 2021, the territory was completely burned out.It is located 1000 m from the edge of the fire deep into the burned area.The deadwood, shrubs, and grassy tier were completely burned out.2010 and 2021 It is located 2000 m from the edge of the fire deep into the burned territory.Similar in all respects to plot 4. 2010 and 2021 It is located 1500 m from the edge of the fire deep into the burned territory.Lowland with water (wet biotope).In 2021, there was a low-intensity fire.Fallen trees and rare birch undergrowth, left over from the fires of 2010, have been preserved.The grassy tier almost completely burned out in 2021.2010 and 2021

Table 2 .
The main parameters of Coleoptera individuals collected using beer traps on various plots (2022 and 2023).