Forest stand structure and coarse woody debris determine the biodiversity of beetle communities in Mediterranean mountain beech forests

Profiling microbial communities in an extremely acidic environment influenced by a cold natural carbon dioxide spring: A study of the Mefite in Ansanto Valley, Southern Italy

The Ansanto Valley's Mefite, one of the Earth's largest non-volcanic CO2 gas emissions, is distinguished by its cold natural carbon dioxide springs. These emissions originate from the intricate tectonics and geodynamics of the southern Apennines in Italy. Known for over two millennia for its lethal concentration of CO2 and other harmful gases, the Mefite has a reputation for being toxic and dangerous. Despite its historical significance and unique geological features, there is a lack of information on the microbial diversity associated with the Mefite's gas emissions. This study presents an integrated exploration of the microbial diversity in the mud soil, using high-throughput sequencing of 16S rRNA (Prokaryotes) and ITS2 (Fungi), alongside a geochemical site characterisation. Our findings reveal that the Mefite's unique environment imposes a significant bottleneck on microbial diversity, favouring a select few microbial groups such as Actinobacteria and Firmicutes for Prokaryotes, and Basidiomycota for Fungi.

Machine learning prediction of tree species diversity using forest structure and environmental factors: a case study from the Hyrcanian forest, Iran

The Hyrcanian forest is a global biodiversity hotspot that harbors many endemic and endangered tree species, but its tree diversity is threatened by various human-induced disturbances, such as logging, grazing, and urbanization. To address this issue, we conducted a study using three machine learning methods, i.e., linear regression (LR), random forest (RF), and support vector machine (SVM), to assess and predict tree species diversity within the forest. To do so, we collected an extensive dataset of forest structure and environmental factors from 2725 sample plots located throughout the forest. The Shannon-Wiener diversity index was used to quantify the tree species diversity for each plot. We found that basal area, tree density, and height of trees were the most important predictors of tree diversity, followed by diameter at breast height, elevation, slope, and aspect. We measured the performance of the models using the coefficient of determination (R2), root mean square error (RMSE), and percent of relative error index (PREI), and found RF as the best-performing model in both the training (RMSE = 0.143, R2 = 0.94, and PREI =  - 0.09) and validation (RMSE = 0.15, R2 = 0.94, and PREI =  - 0.09) phases. RF was able to generalize effectively to new data without losing much accuracy or explanatory power. SVM demonstrated a moderate performance training (training phase: RMSE = 0.23, R2 = 0.57, and PREI =  - 0.17) and (validation phase: RMSE = 0.36, R2 = 0.34, and PREI =  - 0.21) among the models, while LR performed the worst (training phase: RMSE = 0.41, R2 = 0.13, and PREI =  - 0.19) and (validation phase: RMSE = 0.41, R2 = 0.11, and PREI =  - 0.36). These findings have broad applications beyond this specific region and can contribute to promoting sustainable land use practices and conservation efforts in other ecosystems facing similar challenges.

Beetles (Coleoptera) in deciduous dead wood tree species trunks in Lithuania

We present a list of beetles that emerged from wind-felled tree trunks of several tree species, including European ash (Fraxinusexcelsior), aspen (Populustremula), common oak (Quercusrobur), birch (Betula sp.), small-leaved linden (Tiliacordata) and black alder (Alnusglutinosa). Four hundred and ninety species and 60 families of beetles were collected using trunk-emergence type traps. We found 440 beetle species that had previously been recorded from dead wood; the remaining 50 were newly discovered and all were considered as not directly associated with dead wood. Common oak trunks had the highest diversity of beetles, with approximately 42% of the identified beetle species found in our research. Of all the beetle species identified in the study, about half are saproxylic, while the remaining are considered as not having direct association with dead wood. The results of the study emphasise the importance of dead wood in maintaining beetle diversity in Lithuanian forests. This study provides a valuable baseline for future research on beetles in dead wood in Lithuania and may help to provide information for conservation efforts to protect these important habitats.

A preliminary catalogue of the Coleoptera (Hexapoda: Insecta) of the Monte Netto Regional Park (Lombardy NE Italy)

The Po Plain (Northern Italy) is one of the most urbanized areas in Europe. In such a territory, where ecosystem degradation reached critical levels and the agricultural matrix is prevailingly intensive, small fragments of hilly oak-hornbeam forests still persist. Examples of well preserved forests of the Po Plain are those of the Monte Netto Regional Park that represents irreplaceable refuges for both sedentary and migratory species. In this paper we present a preliminary list of Coleoptera inhabiting the Park collected during 10 years of field surveys using several sampling techniques (hand netting, beating tray, sight-collecting and collecting under bark; water nets; litter reducers, light traps; aerial sweet-bait trap; cross-vane panel trap, pitfall traps, Malaise traps, window traps, and walking transects). Specific samplings were also made in tree hollows and by car-netting. To date we have identified 834 species belonging to 531 genera and 71 families (several specimens and some families are still undetermined). Among all the species identified, 31 were non-native while 202 were included in the Red List of Italian saproxylic beetles, 12 of which were in threatened category. The high beetle richness and the presence of many endangered species recorded during this survey, emphasises the conservation value of Monte Netto. Moreover, the discovery of species linked to old and stable forest systems, such as Osmoderma eremita, Oxylaemus cylindricus, Pycnomerus terebrans or Xylotrechus antilope suggests how, despite their small size and the fact that they are surrounded by agricultural land, the remaining forest patches of Monte Netto still possess a fair level of naturalness, especially in the internal areas of the larger plots. Future targeted research, also intended to cover other parts of Monte Netto, could increase our present knowledge; however, and at least in the number of families, we do not expect a substantial increase in species richness.

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

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.

Open datasets wanted for tracking the insect decline: let's start from saproxylic beetles

Background

We present six datasets of saproxylic beetles collected between 2012 and 2018 in Central and Southern Italian forests. Saproxylics represent one of the main components in forest ecosystems in terms of diversity, species richness and functional traits and, for this reason, they are an important target group for studying the modification of forests over time. The datasets consist of annotated checklists and were published on Zenodo repository.

New information

Overall, 1,171 records are published, corresponding to 918 taxa (taxonomy at species or subspecies level). The taxa are scarcely shared amongst the areas, 80.2% of them are exclusive, indicating that the beetle communities are substantially different. In consideration of the biodiversity crisis we are passing through, which is especially dramatic for the insects, we want to promotecollaboration amongst researchers for making datasets available in open repositories. This will improve the possibility for researchers and forest managers of analysing the state of species distribution that could serve for long-term studies on the variation of insect communities. We encourage repeating species assessment in the same localities in order to evaluate the trends in insect communities over time and space.

Vertical Stratification of Beetles in Deciduous Forest Communities in the Centre of European Russia

Studies on the vertical distribution of arthropods in temperate forests have revealed the uneven vertical distribution of communities. Many factors influence these patterns simultaneously. However, there are still many questions related to the vertical distribution of Coleoptera in deciduous forests of the temperate zone. The research was carried out within the territory of the Republic of Mordovia (the center of the European part of Russia). Fermental traps with a bait made of fermenting beer with sugar were used to collect Coleoptera. The collections were carried out from May to September 2020 at five sites in a deciduous forest. We set traps at a height of 1.5, 3.5, 7.5 and 12 m above the ground) on the branches of trees. Ninety-two species were identified at the end of studies at different heights. The families Nitidulidae (15 species), Cerambycidae (14 species), Elateridae (7 species), Curculionidae (7 species) and Scarabaeidae (7 species) had the greatest species diversity. The greatest species diversity was recorded at a height of 1.5 m, while the smallest one was recorded at a height of 7.5 m. The minimum number of specimens was recorded at a height of 12 m. The largest differences in the Jaccard similarity index were obtained between samples from a height of 1.5 and 12 m. The Shannon’s diversity index was higher near the ground than in the tree crowns (at heights of 7.5 and 12 m), and the Simpson index had the opposite tendency. Glischrochilus hortensis and to a lesser extent Cychramus luteus preferred to live in the lowest layers of deciduous forest (1.5 m). Cryptarcha strigata was mainly found with relatively high numbers at heights of 3.5 m and 7.5 m. The abundance and occurrence of Protaetia marmorata and Quedius dilatatus were higher in the uppermost layers of the crowns. The number of saproxylic beetle species at heights of 3.5–12 m was almost the same, while in the surface layer it decreased. The number of anthophilic beetle species was also lower at a low altitude. Our data confirm the relevance of sampling in forest ecosystems at different altitudes while studying arthropod biodiversity.