Žurnal obŝej biologii

The objective uncertainty of the taxonomic category “species” in vascular plants, associated with the lack of clear thresholds in the degree of feature divergence between populations and the continuity of evolution, allows plant taxonomists to arbitrarily divide populations into “species”. In the minds of many researchers, ideas about the special meaning (sacredness) of the species category and the objective existence of species persist. All this negatively affects both the study of the processes of biodiversity formation and the use of the species category in other fields of fundamental science and applied research. The authors consider convenience for identification and usefulness to be the most important parameters in the separation of species. So, the main criteria to separate species should be usefulness as for botanists and for researches in other sciences. According to our expert estimates, at least 80% of the world’s plant taxonomists use this parameter but, possibly, sometimes unconsciously. The possibility and applicability of other criteria, including reproductive isolation and age of taxa, is discussed.

Soil nematode communities in the subcrown space of Siberian larch Larix sibirica Ledeb. both cultivated in botanical gardens and growing in natural forests were studied and compared between each other. The results exhibited significant variations in total nematode abundance at all locations, with both extremely low and high values. The taxonomic diversity of nematodes was higher in the soil under larch in natural forests compared to that in botanical gardens. The larch forest within its range (Altai Republic) distinguished by the high taxonomic diversity of nematodes and highest number of specific taxa (9 genera vs. 1–3 in other points) among all locations. An increase in the relative abundance of plant parasites in the soil under trees cultivated in botanical gardens, as well as nematodes associated with plants under naturally growing larch, were observed in the eco-trophic structure of nematode communities. The evaluation of ecological indices (SI and EI) revealed the presence of transformed soil ecosystems in the subcrown space of larch trees cultivated in botanical gardens. Also, a statistically significant relationship between soil pH and the nematode community maturity index was found. Thus, the patterns obtained can be explained by both the anthropogenic impact on ecosystems associated with tree cultivation activities in botanical gardens and a complex of natural factors (climatic, edaphic, phytocenotic) operating at the investigated sites.

The Barents Sea, a critical Arctic ecotone and a vital fishing region, is undergoing rapid climatic transformation. This process includes Atlantification (intensified inflow of Atlantic waters), progressive warming of bottom layers (1.5–2°C over the past 30 years), and a 20–30% reduction in seasonal ice cover. This study investigates the impact of these changes on the invasive potential of boreal commercial crustaceans – the edible crab (Cancer pagurus), Norway lobster (Nephrops norvegicus), and European lobster (Homarus gammarus) – under three climate scenarios (Shared Socio-Economic Pathways: SSP1-1.9, SSP2-4.5, and SSP5-8.5). Using ensemble species distribution modeling (SDM) integrated with Bio-ORACLE oceanographic data and CMIP6 climate projections, we assessed their potential colonization of the Barents Sea by 2100. Results revealed that under current conditions, the species’ ranges on the Barents Sea shelf are limited to narrow coastal zones off northern Norway (1–2 thousand km²). However, under the extreme SSP5-8.5 scenario (projected 3°C bottom temperature rise by 2100), suitable habitats for C. pagurus would expand to 76.3 thousand km², for N. norvegicus to 67.9 thousand km², and for H. gammarus to 8.5 thousand km², predominantly in the southwestern Barents Sea. The range of H. gammarus would remain constrained to 1–2 thousand km², dependent on rocky biotopes (7–12% of the southwestern shelf), while C. pagurus and N. norvegicus would associate with soft sediments (60–70% of the shelf). Competition with the invasive Kamchatka crab (Paralithodes camtschaticus) may create biotic barriers, though its projected northeastward shift toward Kolguyev Island and Novaya Zemlya is expected to reduce pressure on southwestern areas, opening “ecological corridors” for boreal species. Modeling confirmed the critical role of geomorphological factors: fragmented rocky habitats form isolated “ecological islands”, limiting H. gammarus dispersal, whereas extensive soft sediment zones facilitate the expansion of C. pagurus and N. norvegicus. The SDM approach demonstrated acceptable efficacy in predicting range shifts under climatic uncertainty, highlighting its potential value for ecosystem-based management and ecological monitoring in the Barents Sea.