Earthworms as critical components of natural communities have traditionally attracted the attention of researchers from various fields of biology and agriculture. From the observations of ancient times and up to our time, the research of earthworms has kept its relevance. One of the most interesting tasks has been the creation of an ecological classification of earthworms and its subsequent use. The purpose of this review is to consider various approaches to identifying ecological groups of earthworms (Oligochaeta, Lumbricidae) and the application of these approaches in scientific research. The article reviews the main types of Russian and world ecological classifications of earthworms and some recent additions to these classifications. Particular attention is paid to scientific research with different approaches to the study of ecological groups of earthworms.

Existing estimates of carbon stocks in taiga and coniferous-deciduous forests show that almost half of the total organic carbon in these ecosystems is accumulated in forest soils. Vegetation as the main source of organic matter in the soil, interact with soil biota, which processes plant litter, and with abiotic environmental factors, determines the processes of formation and accumulation of soil organic matter. Changes in the composition of vegetation are the driver of the dynamics of soil carbon stocks; however, insufficient attention has been paid to the analysis of this issue. The review analyzes the main ways of transferring carbon from the vegetation pool to the soil pool and the influence of three main predictors of vegetation that affect the carbon stock in soils: the amount and quality of litter of individual species (species identity) of plants and the structural diversity of the plant community; gaps in knowledge and the ways of development of this scientific direction are proposed.

Relevance and purpose. The Russian geobotanical science has a profound tradition of studying the vegetation cover heterogeneities. However, the number of studies on the mosaics in complexly organized coniferous-deciduous forests is very limited, and there is high ambiguity in the obtained results. In addition, there has appeared a need to resolve the “terminological issue”. The aim of this study was to assess the vegetation cover mosaics of widespread forest phytocenoses in the Moskva-Oka Plain. Material and methods. We present a review of publications on the intracenotic heterogeneity of forest cover and make an attempt to systematize the existing terminology. The field studies were carried out on the territory of the Valuevsky forest park (Novomoskovsky AO, Moscow) using classical geobotanical methods. The acquired data was analyzed with various modern methods of statistical data analysis. Results and conclusions. The obtained results indicate that differences in vegetation are much more pronounced at the level of phytocenoses than at the level of microgroups. The most powerful edificatory effect of spruce has been confirmed. We identified the following reasons that determine the weak differentiation of vegetation at the level of microgroups: the co-influence of neighboring microgroups, the lack of individual trees’ impact duration for a noticeable transformation of vegetation, and legacies in the structure and species composition of previous states over a long period of time.

The formation of databases of digitized vegetation relevés and the publication of content about them promote cooperation between researchers in solving problems of biodiversity analysis, the exchange of the used data, and, thus, the increase in research representativeness. The article is devoted to the review of the origin and use of the database of relevés of forest vegetation and considers the tasks in which it is used. The current stage of work is characterized as follows: improvement of the database structure, features of the stored information, replenishment of the database, issues of administration, and cooperation organization. Based on the analysis of current trends in the vegetation science and taking into account the features of information stored in the database, the relevant scientific problems, for the solution of which the use of the database is promising, and technical tasks that need to be solved to ensure its continued use were formulated.

To date, forest ecology has not made any clear conclusions regarding the impact of large saprophagous invertebrates such as earthworms on soil carbon dynamics. Some authors claim that earthworm activities result in decreased carbon accumulation. Other studies show that earthworms contribute to soil carbon accumulation. At the same time, many studies do not take into account the differences between trophic and digging activity of different morpho-ecological groups of earthworms in different soil horizons. The objective of this study was to carry out differentiated assessment of the impact of different morpho-ecological groups of earthworms on carbon accumulation and correspondent soil parameters (nitrogen content and С/N ratio) throughout the change in forest succession status. Field operations were performed in the spring and summer of 2016 and 2018 in three regions: Bryansk Oblast (Bryansk Forest reserve), Moscow Oblast (Moskva–Oka plain, Valuyevsky urban forest) and Northwest Caucasus (Krasnodar Krai, Apsheron forestry; Republic of Adygeya, Caucasian Biosphere Reserve). Three main stages of coniferous-broadleaf forest restoration after clear cuttings were identified in each region. Three test plots 50х50 m were allocated for each stage; geobotanical and soil descriptions as well as earthworm registration were carried out on each plot. It was found out that during the change in forest succession status the species composition and the set of morpho-ecological groups of earthworms became more complicated, but there was no successive replacement of any groups with others. Ambiguous effects of different morpho-ecological groups of earthworms on carbon accumulation in forest soils were revealed. Negative correlation was found between the total biomass of earthworms feeding on the soil surface (epigeic, epi-endogeic and anecic species) and litter store. In the humus horizon, the biomass of epi-endogeic species was positively correlated with the content of carbon. C/N ratio and nitrogen content are unidirectionally correlated with the biomass of earthworms in the horizons of their activity: with an increase in the biomass of earthworms of different morpho-ecological groups, the C/N ratio decreases, and the nitrogen content increases.

The article provides an overview of Russian and foreign studies on assessment of the composition of atmospheric fallout and soil waters in forest ecosystems. The conclusion was made that little attention is given to the transformation of precipitation chemical composition by forest ecosystems, taking into account the influence of the species composition of the stand and the mosaic structure of the biogeocenosis (areas below the crowns, between the crowns, and open sites). European studies usually look at long-term development of the composition of atmospheric fallout and lysimetric waters, detecting long-term trends in composition changes of atmospheric and soil waters and identifying the factors driving these changes. In Russia, no such long-term (lasting for more than 10 years) continuous observations on the effect of man-made pollution on the composition and properties of atmospheric and soil waters were carried out. This task is very relevant for Russia and, especially, for its industrial regions.

In the zone of broad-leaved forests of the European Russia, steppe meadows have been preserved showing rich floristic composition and making a significant contribution to the biological diversity of the territories. Bryansk oblast is one of the forest regions in Russia where such meadows are found. Here, steppe meadows with high floristic diversity and a large number of rare plant species have survived. Trees from surrounding forest areas are constantly encroaching on these meadows. Most of the young trees die from regular grass fires and economic activity. However, some individuals survive and reach a generative state, becoming relatively resistant to ground fires. The influence of single trees on the floristic diversity of steppe meadows was studied at two levels of living system organization – coenotic and population levels. Polydominant steppe meadows and polydominant steppe meadows with single generative trees were studied at the coenotic level; and coenopopulations of Iris aphylla, Anemone sylvestris, and Anthericum ramosum were studied at the population level. Collecting the material, we used different methods: geobotanical, demographic, and measurements of environmental factors (illumination, slope steepness, and the frequency of grass fires). Polydominant steppe meadows were found to be were preserved in the middle part of steep slopes unsuitable for haymaking and grazing and subjected to infrequent grass fires. These communities have high floristic diversity and stable coenopopulations of model species. Ontogenetic spectra of Anemone sylvestris, Anthericum ramosum, and Iris aphylla are of the complete left-hand type with the maximum number of individuals. Single trees (Quercus robur, Tilia cordata) have controversial influence on the vegetation of polydominant steppe meadows. On the one hand, with the introduction of trees, species diversity of communities increases. This is due to the fact that trees offer resting places and shelter for birds that spread plant diaspores. On the other hand, mature trees shade the herb cover. This leads to cover reduction and occurrence of steppe and dry meadow species, as well as affects their population structure. The ontogenetic spectrum of Anemone sylvestris is still complete, whereas that of Iris aphylla becomes incomplete, and the spectrum of Anthericum ramosum becomes unfinished.