Vladislav D. Leonov

Microbial biomass carbon (C _mic ) is a biologically active pool of soil organic matter and a sensitive indicator that responds to changes in land use much earlier than total organic carbon content and other pools within it. The luminescent microscopy method allows assessing not only the total content of C _mic but also the structure of microbial biomass: the number of spores and the length of fungal mycelium, as well as the number of bacterial cells and actinomycete hyphae. The aim of the study was to determine the structure of the microbial carbon pool in the profiles of chernozem and sod-podzolic soils depending on the type of agricultural use (hayfield, abandoned land, arable land, pasture) using the luminescent microscopy method. The microbial carbon pool in the surface layer of sod-podzolic soil ranged from 260 to 450 µg/g soil depending on the type of land use, in chernozem – 450 µg/g for abandoned land and 190 µg/g for arable land. Down to the depth of 30 cm, C _mic in chernozem under abandoned land was 1.5–3 times higher compared to arable land. In deeper horizons, differences between various land use types became less pronounced but persisted for a number of microbiological indicators. The fungal component, predominantly represented by mycelium, completely dominated (97–99%) the microbial carbon pool in both soils. The length of fungal mycelium in sod-podzolic soil and chernozem decreased by an order of magnitude with depth from hundreds of m/g to tens of m/g soil. Most indicators of the structure of the microbial carbon pool (fungal abundance, mycelium length of fungi and actinomycetes, prokaryotic biomass) were higher in chernozem under abandoned land compared to arable land; however, these patterns were not observed for sod-podzolic soil. Prokaryotic biomass and share, as well as mycelium length, were noted as the only indicators of the microbial carbon pool structure determined by the luminescent microscopy method that were associated with different types of land use for both considered soils. Very high fungi/bacteria ratios are likely due to the underestimation of bacterial cell biomass by the method used. Despite the identified limitations of the method, luminescent microscopy can be used as a supplement to more accurate methods for assessing the microbial carbon pool, allowing the determination of the size and structure of fungal biomass in soils of different types of agricultural land use.

The aim of this study was to estimate the effect of relatively large (1–5 mm) fragments of high-density polyethylene films on two widespread earthworm species belonging to different ecological groups—endogeic Aporrectodea caliginosa and epigeic Lumbricus rubellus. In a microcosm experiment lasting 8 weeks, we tested the food dilution hypothesis, which suggests that the adverse effect of microplastic on earthworms is caused by the dilution of food by plastic, which has zero energetic value. Both earthworm species ingested plastic particles, and both species were seemingly limited by the availability of food. In particular, the addition of food substrate (aspen litter) to the soil had a significant positive effect on the weight of A. caliginosa. In contrast to our expectations, microplastic at relatively high concentrations (0.3% and 2.3% w/w in the soil for A. caliginosa, and 33% and 48% w/w in the litter for L. rubellus) had no significant effect on earthworm biomass. This suggests that the food dilution effect is not likely to be the main mechanism of the adverse effect of microplastic on earthworms. Our work adds to the growing evidence that in many cases microplastic does not harm soil animals.

Some unique asexual species persist over time and contradict the consensus that sex is a prerequisite for long-term evolutionary survival. How they escape the dead-end fate remains enigmatic. Here, we generated a haplotype-resolved genome assembly on the basis of a single individual and collected genomic data from worldwide populations of the parthenogenetic diploid oribatid mite Platynothrus peltifer to identify signatures of persistence without sex. We found that haplotypes diverge independently since the transition to asexuality at least 20 million years ago in European lineages, contrasting Japanese and Canadian lineages. Multiple lines of evidence indicate conservation of one haplotype copy and relaxed selection in the other for the ancient asexual lineages. These findings highlight the evolutionary genomic singularities of ancient asexual oribatid mites that may have contributed to escaping the early demise typically associated with asexuality.

The article describes a new species, Galumnella subiasi sp. nov., from Vietnam, which is distinguished from others by the following combination of characteristics: the notogaster, pteromorphs, prodorsum, and ventral shield have a network pattern; there is an interlamellar ridge on the prodorsum; lamellar and sublamellar lines are parallel; rostral and lamellar setae of medium length; bothridial setae slightly expanded in the middle, unilaterally heavily spinose; notogaster with 10 pairs of short setae; the adanal setae ad3 are located anterior to the anal aperture; postanal porose area absent; all leg tarsi with three claws. An identification key is provided for all Asian species of Galumnella, and it is demonstrated that Galumnella angustifrons and Galumnella nipponica are distinct species.

The carbon isotopic composition of plant tissues is a diagnostic feature of a number of physiological and ecological processes. The most important of which is the type of photosynthesis. In epiphytes, two peaks of δ¹³C values are known to correspond to C3 and CAM photosynthesis and some variants of transitional forms between them. But the diagnosis of δ¹³C may not be limited to the type of photosynthesis. This makes it necessary to study trends in the distribution of δ¹³C in a broader ecological context. In this study, we present trends in the distribution of δ¹³C epiphytes and other structurally dependent plants and their relationship with other isotopic and elemental parameters (δ¹⁵N, C%, N%, and C/N) and with life forms of epiphytes, taxonomic or vertical groups in crowns (synusia), and the parameters of the trees themselves. In all communities except for the moss forest, δ¹³C in epiphyte leaves was significantly higher (less negative) than in phorophyte leaves. In general, δ¹³C in epiphytes in mountain communities (pine forest and moss forest) was more negative than in other communities due to the absence of succulents with CAM. δ¹³C in the leaves of all epiphytes was negatively related to the percentage of carbon and δ¹⁵N in the leaves of the phorophyte. When considering the Gaussian distributions of δ¹³C with the method of modeling mixtures, we observe the unimodal, bimodal, and trimodal nature of the distribution.

Some unique asexual species persist over time and contradict the consensus that sex is a prerequisite for long-term evolutionary survival. How they escape the dead-end fate remains enigmatic. Here, we generated a haplotype-resolved genome assembly based on a single individual and collected genomic data from worldwide populations of the parthenogenetic diploid oribatid mite Platynothrus peltifer to identify signatures of persistence without sex. We found that haplotypes diverge independently since the transition to asexuality at least 20 my ago. Multiple lines of evidence indicate disparate evolutionary trajectories between haplotypic blocks. Our findings imply that such haplotypic independence can lead to non-canonical routes of evolvability, helping some species to adapt, diversify and persist for millions of years in the absence of sex. One-Sentence Summary: Functionally different chromosome sets in an asexual mite species showcase a survival strategy spanning millions of years.

The assessment of biological diversity and the processes that govern it is important for ecological research and nature conservation. This review describes the main general theories and presents the modern concept of mechanisms for the assembly of ecological communities. Deterministic (abiotic filter and biotic interactions) and stochastic (ecological drift, dispersal and speciation) processes influencing taxonomic, functional and phylogenetic facets of diversity are discussed. Impact of certain processes (influence of individual environmental factors, biotic interactions, dispersal limitation) on the α- and β- levels of each facet of biodiversity are shown. In turn, estimation of them makes it possible to assess the contribution of certain processes on the biodiversity of the studied local communities.

The description of a new species of oribatid mites (Oribatida) of the family Zetorchestidae—Zetorchestes krisperi sp. nov.—is proposed based on adult and tritonymph specimens collected from rainforest soil of Bi Dup-Nui Ba National Park (southern Vietnam). We also review the distinguishing characteristics for Zetorchestes species and present an identification key to Zetorchestes species of the world. Diagnostic features of Zetorchestes nymphs are discussed.

Plastic pollution of the environment (including soil) is one of the world’s great problems; however, little is known about the effect of synthetic polymers on the soil community. This review summarizes the results of experimental research on the effects of plastic on different groups of soil animals (21 studies) and soil animals on plastic in the soil (13 studies). The presence of microplastic in soil has a negative influence on nematodes, collembolans, pot worms, and earthworms. The mechanisms of this influence often involve damage or dysfunction of the digestive system. On the other hand, soil animals can contribute to the mechanical degradation of plastics and stimulate their microbial degradation in soil. Based on the extensive experience in studying the consequences of plastic pollution of marine ecosystems, we discuss the main problems, tasks, and prospects of studies on the interaction between plastic and soil animals.