Scot pine (Pinus sylvestris L.) is one the main forest-forming tree species in Russia, and is of great ecological, economic and social value. In order to manage the genetic resources of this important forest tree species efficiently, knowledge of its genetic diversity and structure is needed. Here, we assessed the genetic variation of 17 populations representing different parts of Scots pine range in Russia by using nuclear microsatellite markers (nSSR). Specifically, 14 populations were chosen within the natural distribution range of the species in Middle Siberia and three distant populations were sampled from the European part of Russia, the West Siberia and the Russian Far East. All populations showed high values of genetic diversity (HE = 0.514) and AR = 4.150. However, the easternmost population has shown the lowest level of genetic diversity (HE = 0.433) and allelic richness (AR = 3.505). Five genetic groups could be detected that correspond to: the European part of Russia, the south of Middle Siberia, the northwest of Middle Siberia, West and Middle Siberia, and the Russian Far East. However, the European population was the most genetically distinct one. The variation among Scots pine populations accounted for only 5% of the total variance. The highest level of genetic differentiation was found only between westernmost and easternmost populations (FST = 0.097). Our genetic data may contribute to a better understanding of the pattern of genetic diversity of Scots pine populations in Middle Siberia and help the conservation efforts of these genetic resources.

Scots pine (Pinus sylvestris L.) is a widespread and economically important tree species in Eurasia. Southern Siberian, Scots pine mountain and foothills forests are especially valuable natural objects that help to stabilize environmental conditions. Due to the associated impact of natural and anthropogenic factors, the habitats of the species in southern Siberia are constantly shrinking. In this regard, the study of genetic diversity and structure of Scots pine forests in southern Siberia is very relevant. Here, we studied the genetic diversity and structure of eight Scots pine populations located in southern Middle Siberia (Russia). A high level of genetic diversity (HE = 0.518) was detected in the studied populations. No recent bottleneck effect, isolation by distance or isolation-by-environment were detected. Most genetic diversity was found within populations, while only 7% of genetic diversity occurred among populations. Both STRUCTURE analysis and UPGMA clustering showed two genetic groups. Two populations from the Minusink basin and a population from the Western Sayan Mts. formed the first group and the second group was composed of the other populations from Kuznetsk Alatau Mts., Central Tuva basin and Todzha basin. Our findings suggest that the studied Scots pine populations originate from different gene pools. The pattern of genetic diversity revealed by our study may be useful for the elaboration of conservation measures of genetic resources of Scots pine in southern Middle Siberia.

Abies sibirica Ledeb.-dominated stands degradation is of special concern. Nevertheless, insufficient attention is paid to the role of pathogens in this process. The aim of the present study is to assess the coenotic role of infectious diseases in fir-dominated stands in the south of Central Siberia. The research was based on a forest pathological examination conducted in A. sibirica-dominated forest stands in the Krasnoyarsk Krai. The cenotic role of the identified diseases is unequal. Stem decay and fir broom rust are typical diseases that weaken trees and induce rotten windsnap accumulation. Fir broom rust randomly affects trees of different age and size. The prevalence of fir broom rust in the studied fir stands reached 10% or more. The most hazard diseases in the studied stands are bacterial soft rot and root rot. Bacterial soft rot damages up to 20% of trees and causes their gradual dieback. The main cause of tree mortality in fir-dominated stands is root rot. The root rot-causing fungi lead to rapid dieback of trees of different cenotic status. In synergy with other factors, root rot acts as a significant endogenous factor in the current reorganization of coniferous forest ecosystems in the south of Central Siberia.