Vol 86, No 1 (2025)

Proposed is a method for assessing the biological productivity of forest ecosystems, which allows to overcome the disadvantages inherent in the traditional methods, not taking into account the significant statistical heterogeneity of stands on a number of morphometric parameters that change in the process of forest ecosystem development. The concepts and tools of the theory of stationary random functions were used in the development of the method. The central idea of the proposed method is the concept of a hypothetical average tree characterizing the growth of a pure stand at the main stages of its development. The final result of this methodological approach is the stand bioproductivity index, which provides a quantitative assessment of bioproductivity and allows comparing the bioproductivity of pure stands growing in different climatogeographical conditions. The practical application of the method is considered on the example of stands of Siberian fir (Abies sibirica Ledeb.). The relative error of the bioproductivity index of fir stands is estimated. The method was validated on the basis of revealing correlations between the index of fir stand bioproductivity and ecological assessments of habitats obtained using phytoindicator properties of the ground cover.

The paper presents the characteristics of the main components of the carbon cycle in the ecosystems of mature spruce forests: blueberry moist, polytrichum-sphagnum, and in fellings of these spruce forests on peaty podzolic gley soils. Income and expenditure items of the carbon budget of phytocenoses are assessed according to the indicators of production and destruction processes of organic matter. It has been established that the total carbon pool in the ecosystems of mature spruce forests is 160–194 t∙ha⁻¹, of which in plants of phytocenoses 44.4–57.8%, in large wood residues (deadwood) 2.1–9.7%, in the soil including litter and mineral layer 35.8–45.9%. In the ecosystems of fellings carbon reserves of organic matter are equal to 106–113 t∙ha⁻¹, of which in soil 62.5–72.5%, in phytocenoses plants 18.0–25.2%, in large wood residues 9.5–12.3%. The annual carbon sequestration by phytocenoses of mature spruce forests is 2.4–3.5 t∙ha⁻¹, in felled areas – 1.8–2.2 t∙ha⁻¹. In the accumulation of carbon in spruce forests the leading role belongs to the tree stand, and in the fellings – to ground cover plants. The amount of carbon entering with the litter is 2.0–2.1 t∙ha⁻¹ in spruce forests, and 1.4–1.6 t∙ha⁻¹ in fellings. The carbon released during the decomposition of the litterfall plant residues in the fellings is 0.54–0.63 t∙ha⁻¹, which is 37.2–37.6% of the annual decomposition of the litterfall plant residues. It is shown that mature spruce forests are a place of sink and fellings is a source of carbon.

Thе study presents the ecological, zoogeographic, biotopic, ontogenetic, and phylogenetic features that contribute to the formation of diverse parasite communities in redfish of the genus Sebastes, which inhabit the Arctic Ocean. The study was conducted by performing a complete parasitological dissection on 956 individuals of redfish from three species. The detected parasites were identified and subjected to taxonomic, hostal, age-specific, eco-geographical, and quantitative analyses to understand the specific characteristics of the parasite fauna in these fishes. The study determined that parasite species belonging to the epicontinental, mesobenthic, and polyzonal ecological complexes were dominant, with a predominance of arctoboreal species. The species diversity of parasite communities in the ontogeny of redfish is influenced by their species, biotopical, and age-related trophic peculiarities. The variation in parasite communities’ structure among various species suggests that the ecological differentiation of redfish in the Sebastes species is influenced by the processes and sequence of their speciation in the incompletely spatially isolated biotopes. This sequence resulted in the offshore shift of distribution to deeper shelf, bathypelagic, and mesopelagic areas in the succession of redfish species: Sebastes viviparus → S. norvegicus → S. mentella. The opinion is provided regarding the species structure of the researched part of their ranges, based on the findings of analyzing the geographical features of their parasite communities. Life strategy of beaked redfish S. mentella as the phylogenetically youngest species of the genus Sebastes aiming at the extension of the distribution range and colonization of new biotopes induced the formation of the pelagic and demersal intrapopulation groupings.