CENOTIC ROLE OF INFECTIOUS DISEASES IN ABIES SIBIRICA LEDEB. STANDS IN THE SOUTH CENTRAL SIBERIA

Abstract

Background. Degradation of Abies sibirica Ledeb.-dominated forests in the South Central Siberia is a reflection of the global trend of coniferous forest ecosystems decline. Nevertheless, the role of infectious diseases in coniferous forests degradation and dieback is often underestimated.
 Research aim. To assess the coenotic role of infectious diseases in fir-dominated stands in the South Central Siberia, considering the differentiation in trees.
 Materials and methods. The research was based on a survey of A. sibirica-dominated forest stands growing in Biryusinsky forest management unit of the Krasnoyarsk Krai government-owned publicly funded “Emelyanovskoye forestry”. Research methods included a detailed (instrumental) forest pathological examination, macroscopic diagnostics of tree diseases, graph analytics and statistical analysis of tree diameter distribution series, evaluation of disease manifestation indicators.
 Results. Stem rot and fir broom rust are typical diseases increasing the risk of windsnap and trees weakening. The prevalence of fir broom rust was over 10%. Rust fungus intermediate hosts in the forest floor determine the degree of damage to a stand. Fir broom rust randomly affected trees of different age and diameters. The bacterial blight in fir forests mainly affected trees of I-II Kraft classes causing their gradual dying. The bacterial blight in the study area was of low infection degree (up to 20%). The most dangerous was the root rot caused by Armillaria mellea s.l. that affected trees of different cenotic roles causing their group dieback.
 Conclusion. Dendropathogenic organisms are an important endogenous factor influencing the state of dark coniferous forests with a predominance of A. sibirica in the South Central Siberia. Their cenotic role is unequal. The most significant are pathogens causing necrosis and cancer diseases, and especially the root pathogen A. mellea, which leads to weakening and dying of a large number of trees of different status in the stand structure.