Diseases of Populus tremula L. in the subtaiga forests of the Yenisei Siberia: pathogens and their impact

Abstract

P. tremula (aspen) stands in boreal forests usually act as an intermediate stage of regenerative successions. One should not underestimate the role of ecological functions provided by aspen forests and their resource potential. Aspen forests occupy up to 25% of the most intensively exploited forests of the Krasnoyarsk Krai. Dendropathogenic organisms often determine P. tremula stands condition. The research is aimed to study the phytopathological state of P. tremula stands in the subtaiga forests of the Krasnoyarsk Krai. The study was carried out in the subtaiga aspen forests of the Educational and experimental Karaulny forestry enterprise of the Reshetnev Siberian State University of Science and Technology (Reshetnev University). Research methods included route and detailed forest pathological examination (on four sample plots), complex macroscopic diagnosis of diseases, identification of signs and symptoms of the diseases, and the diameter distribution series analysis. A significant part of the aspen forests in the study region suffers varying degrees of disturbance. Pathogenic biota composition includes fungi and bacteria differing in their parasitic activity and specialization. Hymenomycete Ph. tremulae is the most common in aspen stands. Stem rot caused by Ph. tremulae increases the risk of wind damage and reduces the value of forest stands. The main biotic factors affecting aspen forests are bacterioses causing necrosis canker and root rot caused by A. mellea s. l. These widespread diseases have a systemic negative effect on trees of different cenotic status in aspen forests; they usually form foci in adjacent areas, which accelerate the destruction of forest stands. Accumulation of A. mellea s. l. infection in aspen forests is potentially dangerous for coniferous plantations. Micromycetes affecting the phyllosphere lead to the weakening of young aspen trees. V. tremulae sometimes causes the undergrowth to dry out.