Enchytraeids are key organisms in the functioning of terrestrial ecosystems, but despite this, the fauna and population of enchytraeids of the European part of Russia (ER) have been studied rather poorly. Based on our own collections from 193 sites across the main biomes of the ER from 2019 to 2023, 74 species of enchytraeids belonging to 15 genera were identified. The presence of tundra, boreal, nemoral and desert faunal complexes of enchytraeids, as well as a group of polyzonal species, was shown. From a faunal perspective, the Caucasus, which is inhabited by a group of species that are not found anywhere else in Russia, stands out within the ER. Analysis of enchytraeid communities in various biomes of the ER at the species level will allow for a more correct assessment of their role in detrital food webs and the functioning of ecosystems overall.

Enchytraeids, also known as pot worms, represent one of the least studied groups of soil mesofauna. These organisms can be found throughout the globe from coasts to deserts reaching high densities and biomass, but their specific roles within the soil food web remain a stark knowledge gap. Enchytraeid species are involved in belowground trophic interactions, which could be distinguished by their morphological characteristics and ecological traits. To quantify this, we analyzed stable isotopes δ13C and δ15N in 16 enchytraeid species across various biomes and habitats in European Russia. Their isotopic niches were compared with different potential food sources and other soil invertebrates. We found that the total δ13C and δ15N range by across single enchytraeid samples reached 8 and 11‰, and isotopic niche of species depends on soil stratification and is reflected in the chaeta number per bundle, and, to a lesser extent, on the size or genera identity. These findings enabled us to split enchytraeids into three guilds within the functional group of secondary decomposers: (i) epigeic – that include litter-dwelling species that predominantly feed on plant material but also can ingest microorganisms; (ii) epi-endogeic – inhabiting upper humified soil and F-litter horizons, and feed primarily on various saprotrophic microorganisms; (iii) endogeic – consuming old processed humified and dissolved organic matter in lower H-horizon and even mineral A-horizons beneath. Our results are an important step forward in integrating enchytraeids into the next-generation food web models, not as a single black box, but as multiple blocks delivering different functions.

Enchytraeids are among the key organisms in the functioning of terrestrial ecosystems. Despite this, the fauna and population of enchytraeids of the European part of Russia (ER) have been studied rather poorly. Based on our collections gathered at 193 sites in the territory of the main biomes of European Russia in 2019–2023, 74 species of enchytraeids assigned to 15 genera were identified. The presence of tundra, boreal, nemoral, and desert faunal complexes of enchytraeids, as well as of a group of polyzonal species, was shown. From a faunal point of view, the Caucasus, which is inhabited by a group of species that are not found anywhere else in Russia, is distinguished in the European part of the country. Analysis of enchytraeid communities in various biomes of the European part at the species level would allow a more correct assessment of their role in detrital food webs and the functioning of ecosystems in general.

Enchytraeids, also known as pot worms, represent one of the least studied groups of soil mesofauna. These organisms can be found throughout the globe from coasts to deserts reaching high densities and biomass, but their specific roles within the soil food web remain a stark knowledge gap. Enchytraeid species are involved in belowground trophic interactions, which could be distinguished by their morphological characteristics and ecological traits. To quantify this, we analyzed stable isotopes 8 13 C and 8 15 N in 16 enchytraeid species across various biomes and habitats in European Russia. Their isotopic niches were compared with different potential food sources and other soil invertebrates. We found that the total 8 13 C and 8 15 N range by across single enchytraeid samples reached 8 and 11 parts per thousand, and isotopic niche of species depends on soil stratification and is reflected in the chaeta number per bundle, and, to a lesser extent, on the size or genera identity. These findings enabled us to split enchytraeids into three guilds within the functional group of secondary decomposers: (i) epigeic - that include litter-dwelling species that predominantly feed on plant material but also can ingest microorganisms; (ii) epi-endogeic - inhabiting upper humified soil and F-litter horizons, and feed primarily on various saprotrophic microorganisms; (iii) endogeic - consuming old processed humified and dissolved organic matter in lower Hhorizon and even mineral A-horizons beneath. Our results are an important step forward in integrating enchytraeids into the next-generation food web models, not as a single black box, but as multiple blocks delivering different functions.

The present study focuses on investigating the taxonomic richness and composition of selected groups of soil microfauna, specifically soil ciliates and nematodes, within municipal solid waste landfills located in European Russia.Faunistic surveys were conducted across two landfills, with soil samples collected in the three zones: core sites within the landfill, at the edge of landfills, and control sites located 1 kilometer away from the edges.We revealed distinct faunistic patterns between the landfills core and edge sites vs respective controls.Core sites within the landfills exhibited higher ciliate species richness and nematode abundance.This highlights the landfill effect on soil microfauna community composition.Importantly, certain species of ciliates were exclusively found within the landfills, indicating the presence of a faunistically distinguished community associated with communal waste deposition.Knowing peculiarities of soil microfauna communities in landfills brings ground to further knowledge understanding of soil ecological processes in the landfills.This further opens perspectives for a development of adequate management practices for sustainable communal waste disposal and landfill remediation efforts.

‘Hidden hunger’ occurs in humans and livestock and stems from deficiencies in microelements, essential amino acids, and vitamins. Triggered by insufficient intake of micronutrients in food and feed, even when macronutrients are abundant, hidden hunger can result in the development of serious diseases and pathological conditions. Finding sufficient micronutrients is often challenging because they are either obtained from limited external natural sources or synthesised de novo . Soil-dwelling saprophages comprise one of the largest proportions of zoomasses on Earth but remain surprisingly overlooked as a potential micronutrient source. To assess their nutritional content concerning micronutrients, we selected 31 invertebrate species obtained from natural ecosystems of European Russia or widely cultivated species originating mainly from tropical regions. They belong to major soil saprophage taxa: cockroaches (Blattodea), beetle (Coleoptera) larvae and imagoes, springtails (Collembola), millipedes (Diplopoda), fly (Diptera) larvae, earthworms (Haplotaxida), woodlice (Isopoda), crickets (Orthoptera). We assessed their proteinogenic amino acid, microelement, and vitamin composition. Taxonomic differences in the composition and ratio of micronutrients were determined and we identified specific taxa naturally enriched with micronutrients for future consideration as potential candidates for incorporation into food and feed supplements to alleviate hidden hunger in livestock and humans.

Marine macroalgae are often used as biofertilizers in the coastal regions across the world. However, the effects of soil fauna in macroalgae decomposition are not fully understood. We conducted a microcosm experiment to assess the possibility of using a mixture of native Enchytraeidae and the model earthworm species Eisenia fetida to accelerate decomposition of dominant algae taxa from White Sea (Fucus spp.) and Black Sea (Cystoseira spp.) after their amendment to soil with simultaneous mitigation of the associated carbon dioxide (CO2) emissions. During 45 days of the microcosm experiment, we measured CO2 emission from the soil and evaluated changes in macroalgal biomass, 813C and 815N isotopic signatures of soil, macroalgae, earthworm faeces and enchytraeid tissues as well as bulk carbon and nitrogen content in soil. The mass of Cystoseira spp. residues, unlike that of Fucus spp., significantly decreased during the experiment (by approximately 73 % of the initial level). This effect was amplified by the co-action of E. fetida and Enchytraeidae (by 65 % of the initial). The addition of Enchytraeidae into microcosms led to the more than two-fold reduction of CO2 emission in all treatments. Differential enrichment of soil and earthworm casts with macroalgae-derived carbon and nitrogen, as suggested by stable isotope analysis, indicated that macroalgae-originating carbon pathway is rather driven by a synergistic activity of enchytraeids and earthworms (813C enrichment up to 4.8 parts per thousand). Nitrogen transfer was dependent on the microbial activity and could be modulated and channelized by enchytraeids, whose 815N values strictly corresponded to algal taxa. This highlights the importance of annelids in increasing the value of macroalgae as biofertilizers.

Rice crop residues are one of the recalcitrant agricultural wastes in arid conditions. A laboratory experiment was conducted to decompose rice straw with woodlice and millipedes living in the dry steppes of Kalmykia in Russia. Five individuals of two species of woodlice (Armadillidium vulgareandProtracheoniscus kryszanovskii) or two species of millipedes (Brachydesmus assimilisandCylindroiulussp.) were placed in microcosms with soil and 2.5 g of rice straw. The straw mass significantly decreased for all species, by approximately 50% on average for the 4 months of the experiment. The content of organic matter in the soil before and after the experiment did not change significantly, which suggests that the selected species of woodlice and millipedes can consume and, thus utilize, rice straw, at least under experimental conditions.

Communities of soil animals (meso- and macrofauna) in rice paddies tend to be fragmented, and have extremely low abundance. Nevertheless, some groups, such as enchytraeids, may become dominant in flooded conditions, as shown in tropical rice agroecosystems. However, the fauna and functional composition of enchytraeids (Annelida, Clitellata, Enchytraeidae) under such conditions have not yet been studied at temperate latitudes. We have investigated enchytraeid communities and the ratio of their functional groups in the main rice-growing regions of Russia: Krasnodar krai, Primorsky krai, and the Republic of Kalmykia. Samples were taken in summer–early autumn of 2016 in four habitat types: flooded rice paddies, drained paddies occupied by upland crops, adjacent bunds, and undisturbed grasslands (control). Generalized linear model analysis showed that the factor habitat type and its interaction with the factor region had a significant effect on the total enchytraeid abundance, with the factor region alone having no such effect. Their abundance was the highest in the control habitats and bunds (mean and standard error for all the regions: 3278 ± 1131 and 3255 ± 762 ind./m2, respectively), being insignificantly lower in the paddies under upland crops (1282 ± 850 ind./m2) and decreasing to a minimum of 415 ± 323 ind./m2 in the flooded paddies. A comparison between the last two habitat types shows that enchytraeids can relatively quickly restore their abundance in the rice paddies after draining. Principal component analysis revealed a positive correlation between the density of enchytraeids belonging to basophilous ecological group and bioavailable phosphorus content. The correlation between the abundance of acidophilous enchytraeids and this parameter was negative. Thus, the abundance ratio of enchytraeid ecological groups could be used as an informative indicator of the concentrations of nutrient elements and depends on physical and chemical characteristics of paddy soils. Despite the low abundance of enchytraeids in these soils, they can be an important component of the detrital food webs during periods of paddy-drainage in intensive rice agroecosystems at temperate latitudes.

Two new oribatid mite species collected in the park zone of Yuzhno-Sakhalinsk (Sakhalin Island, Russia) are described. Xenillus similis sp. n. is a large pale brown mite with lamellae covering the major part of the proterosoma. Its cusps are separate, large, and blade-shaped with sharpened diverging medial teeth. The translamella is narrow with a tiny tooth between the cusps. Sensilli are fusiform. The new species differs from the closely related X. sculptrus Kulijev, 1963 in the finer rostral and lamellar setae, long interlamellar setae, and different shape of sensilli (fusiform vs. clavate), lamellae (in X. sculptrus they are broadened towards the anterior end), and cusps. The new species differs from X. tegeocranus (Hermann, 1904) in the presence of fine and poorly pubescent dorsal and ventral setae, shorter lamellar setae, longer and sparsely pubescent interlamellar setae, the fusiform sensilli (vs. clavate), and the shape of cusps with more elongated internal teeth. Lasiobelba (Lasiobelba) sakhalinensis sp. n. is a middle-sized mite with slightly projecting and rounded rostrum. Costulae are absent, prodorsal setae are smooth. Sensilli are fusiform without apical spine. Ten pairs of notogastral setae are long and smooth (except for setae c which are represented by alveoli); p1–p3 are shorter than other setae. The anogenital setae are fine and smooth. The discidium is pointed. Leg claws are fine. The new species differs from morphologically similar L. (L.) remota Aoki, 1959 and L. (L.) insulata Ohkubo, 2001 in the smaller size, fusiform sensilli without apical spine (both L. (L.) remota and L. (L.) insulata possess long sensilli widened in the middle part and with the apical spine), shorter interlamellar setae (in compared species, they nearly reach bases of lamellar setae), and in the smooth prodorsal and notogastral setae.

We investigated fauna and community composition of springtails in the burnt and unburnt boreal forests of European Russia.We also analyzed ecoregional differences in the effect of fire disturbance on collembolan community faunistic similarity on an example of three different ecoregions of the boreal forest biome in the study territory.We collected and identified 6799 springtail individuals representing 14 families, 41 genera and 94 species.In the burnt plots we observed consistent shifts in the springtail community dominance structure across all studied ecoregions.The effect of fire on the faunistic similarity of springtail communities was strongly modulated by ecoregion: within-ecoregion similarity between plots was always higher than the between-region similarity.Fires resulted in the moderate decrease of the total abundance of springtails with trans-holarctic distribution in all ecoregions and additionally in increase of springtails with west-palaearctic distribution in southern ecoregion.We conclude that five years after burning it is very important to standardize fire-induced changes in the faunistic composition of springtail communities to the actual geographic location within spatially extensive biomes.

We assessed the impact of forest fires on macrofauna taxonomic richness, abundance and total biomass in 20 forests burnt five years ago and 20 respective control plots along a 3000-km-long north-south transect in European Russia that covered five major forest types (Mediterranean and broadleaved forests, southern, middle, and northern taiga). In parallel we assessed basic soil abiotic parameters in these stands. Within forest type, the spatial variance of macrofauna total biomass was 1.8 times higher in the burnt forests than in the controls. Due to this increase of variance in the burnt forests, the main effect of forest type on soil macrofauna parameters was generally weaker. Among different soil abiotic parameters, higher level of uniformity of macrofaunal community parameters between different forest types was explained by the labile P and N content in the soil, water-holding capacity and soil moisture. Presence of open areas within the burnt forests seems to be the leading driver of the increased similarity of soil macrofauna communities across different forest types. Forest fires thus act as a powerful force that raises within-forest-type soil macroinvertebrate beta-diversity and associated biomass fluctuations. At the same time burning reduces soil macrofauna gamma-diversity due to increased faunistic similarity between different forest types. This has potentially important implications for the functioning of soil macroinvertebate communities in the pyrogenic forests and its dependency on macroclimatic conditions.

Functionality of soil food webs after forest fires remains generally unexplored. We address this question by studying both burnt and unburnt spruce forests in Central European Russia (Tver Region). In August 2014 we sampled two spatially distant blocks consisting of forest areas burnt in 2010 and the respective unburnt controls. We analyzed biomass and structure of soil food webs as well as carbon mobilization with respect to carbon stocks in the dead wood, litter and soil after burning. The biomass of soil fauna was moderately reduced in the burnt plots. For some groups like testate amoebae and enchytraeids, however, this decrease was highly significant and corresponded with the decreased C-stock in litter. For the other taxa changes in biomass were insignificant. At the same time C-flow through the soil food web after fire was strongly reduced mainly due to the reduction of biomass of active fungi and secondary decomposers. The overall consumption rate of detritus by the soil food web strongly decreased in the burnt forests and was maintained predominantly by the decomposition activity of bacteria instead of fungi. This resulted in the reduction of the total soil food web functionality related with C-mobilization in the forests four years after a fire event.

Relations between soil biota diversity and its contribution to the performance of some ecosystem functions were assessed based on the results obtained in undisturbed and burned spruce forests near the Central Forest Nature Biosphere Reserve (Tver oblast). In August 2014, in two 4-year-old burned areas, abiotic parameters of the soils, indicators of the state of the microbial communities, the number, taxonomic diversity, and the abundance of the main groups of soil invertebrates (testate amoebae, nematodes, enchytraeids, mites, collembolans, and the mesofauna as a whole) were determined. In the soils of the burned areas, higher CO 2 , CH 4 , and N 2 O emissions were observed. The number of bacterial cells remained similar, and the total length of active mycelium was not significantly different. All this implies a certain intensification of biogenic processes promoting the mobilization of carbon and nitrogen after fire. The number of most of the groups of soil animals was lower (not always significantly) in the burned area than that in the soils of the undisturbed forests. The changes in the taxonomic diversity were specific for each taxon studied. Overall, the diversity of invertebrates was related to the litter thickness. However, the high taxonomic diversity of soil fauna did not always correspond to the active functioning of the ecosystem. Thus, for some taxa, a quite close correlation was found, for instance, between the total number of species (of testate amoebae in particular) and the berry crop, as well as between the soil mesofauna population and the dead wood stock. The total diversity of the investigated taxa included in the detrital trophic web was the most reliable indicator of the carbon stock in the burned areas.