Forest Science

Wood-destroying fungi are considered the most important endogenous indicator in the dynamic processes of native spruce forests formation of different ages in the European Russia’s taiga. Spruce biogeocenoses of evolutionary formation on different development phases (climax, demutation, digression) have been studied in the southern, middle and northern taiga subzones. Experimental studies show various variants of the successional changes dynamic, the damage rate of forest stands by wood-destroying fungi of the biotrophic complex and the consistency of these indicators regardless of forest growth zones and types of forest growth conditions. The relationship between the age and the infestation rate of trees by fungi of the biotrophic complex by age generations, studied with different approximations: linear, exponential and polynomial, has different values: from “very strong”, almost functional — R² > 0.9, “strong” — R² = 0.7—0.9 to its absence — R² = 0.089. The highest values of volume and percentage indicators of rot within spruce biogeocenoses belong to communities of climax-digressive phases of dynamics. Wood-destroying fungi of the biotrophic complex are one of the main heterotrophic structures of native spruce biogeocenoses, performing the function of rotten damage to trees and their fall into the structure of the biogeocenosis mortmass, consistent with the successional dynamics of the community.

In the theory of plant morphogenesis, the process of assimilate distribution between their organs remains poorly understood. The optimal distribution of assimilates between vegetative organs plays an important role in the use of available resources, however, the processes of assimilate distribution across vegetative organs are quite complex and difficult to measure, and the result of these processes is estimated by the structure of phytomass distribution across vegetative organs. According to the optimal partitioning theory (OPT), plants allocate most of their assimilates to the organ that uses the most limited resources to optimise plant functioning. In previously published interpretations of the OPT, partitioning relative phytomasses of organs in plants was studied either in relation to their phytomass (“true plasticity”) or in relation to their age (“ontogenetic plasticity”), although the actual distribution of phytomasses is the result of the combined action of these two factors. In this study, using the database of seven forest-forming genera as aggregates of vicarious species of the boreal zone, a modification of the patterns underlying the OPT in the organs of trees was performed. A two-factor regression analysis of the relative phytomasses of aboveground and underground organs of trees was performed based on a mixed model, in which numerical independent variables are represented by the age and total phytomass of the tree, and dummy variables mediate the affiliation of the initial phytomass data to each of the seven genera. Relative phytomasses are represented by the ratio of aboveground or underground phytomass to the total phytomass of a tree. The age-related reversal of the relationship of relative phytomasses with total phytomass has been revealed: the relationship of relative aboveground phytomass with total, positive at a young age, is replaced by negative at maturity and vice versa, the negative relationship of relative underground phytomass with total at a young age is replaced by positive at maturity. Thus, the relative aboveground phytomass at a young age has priority in the distribution of assimilates in the largest trees, but as the age increases, reversion occurs and this priority shifts towards the smallest trees. On the contrary, the relative underground phytomass at a young age has priority in the distribution of assimilates in the smallest trees, but as the age increases, this priority shifts towards the largest trees. The ages of the described patterns reversal have been established, which are the same for all genera: 20±0.5 years for relative aboveground phytomass and 40±2.5years for relative underground one.

Common hazel (Corylus avellana L.) is a species that is widely distributed in various regions of the Russian Federation. It is a particularly valuable shrub due to its qualities. Its nuts, which have valuable food qualities, are of the greatest interest. To create a high-quality variety pool of the species, it is very important to study the polymorphism of its fruits and the occurrence of individual forms with selectable traits in various growing conditions. This is especially important in the mountain forests of the Northwest Caucasus, where the plant has significant polymorphism, which is least studied at the upper vegetation limit in the formations of the Oriental beech (Fagus orientalis Lipsky) and the Caucasian fir (Abies nordmanniana (Steven) Spach.). The goal of the research is to study the polymorphism of common hazel nuts and to predict the occurrence of species’ forms in these conditions. In the formations 467 fruits have been studied for 11 selection-significant indicators using a technique that takes into account the selection distribution of indicators and the iteration of averages, and the features of the statistical distribution of quantitative traits. To identify the relationship between the presence of fruit diversity and forms, long-term data on 1955 fruits and 258 forms selected as promising for further selection in the studied area have been used. It has been found that in the formations of the Oriental beech, the distribution of the indices of colour, shape, nut height, flavour and kernel yield, nut and kernel weight in common hazel significantly differs from the conditions that develop in the formations of the Caucasian fir. The distribution of hazel nuts does not have a statistically significant difference according to the strength of the shell, indestructibility of the kernel and the presence of husk on it, the total score of the selection value. In these formations, a very frequent occurrence of plants with a whole kernel of a very good taste, the selection category of ordinary, often with a light, easily split shell and a kernel without husk is predicted. An increase in the database on nut polymorphism does not exclude the transition of indices to neighbouring gradations when predicting the occurrence of forms.