FIR (ABIES SIBIRICA LEDEB.) MORTALITY IN MOUNTAIN FORESTS OF EASTERN SAYAN RIDGE, SIBERIA
V. I. KHARUK1,2, A. S. SHUSHPANOV1,3, I. A. PETROV1, D. A. DEMIDKO1, S. T. IM1,2,3, A. A. KNORRE2,4
1V. N. Sukachev Institute of Forest of SB RAS, Кrasnoyarsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia
3Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, Russia
4”Stolby” State Nature Reserve, Krasnoyarsk, Russia
Keywords: изменения климата, засуха, усыхание хвойных древостоев, Abies sibirica, пихта сибирская, атаки насекомых, Polygraphus proximus, жуки-короеды, tree mortality, coniferous decline, climate change, pest attacks, bark beetles, Polygraphus proximus, drought, Abies sibirica, Siberian fir
Abstract
In the initial phase of climate warming, an increase in radial increment was observed, which was replaced by a depression in 1985-2017. The declining of fir trees was preceded by an increase in the relationship between growth index and SPEI, also between growth index and root zone moisture content. At the same time, growth index of the declining cohort was more closely associated with root zone moisture content ( r2 = 0.56) and SPEI ( r 2 = 0.74) than growth index of the surviving cohort ( r 2 = 0.15 and r 2 = 0.39, respectively). Fir declining began in the 2000s, when Abies sibirica trees, weakened by water stress, were attacked by Polygraphus proximus Blandford. During this period, dead stands were localized mainly on the relief elements with the highest probability of water stress (steep slopes located in “rain shadow”). By 2017, the declining spread throughout the entire territory of fir stands, which led to the mortality of ~75 % of fir stands. During the period of tree declining, a close relationship was observed between growth index and fir mortality ( r = -0.79). The surviving trees grew in conditions of a higher humidity of root zone (compared to declining trees). Noteworthy is the proximity of growth index trajectories of cohorts of declining and surviving trees, which indicates the probability of mortality of surviving trees in the context of a predicted climate aridity increase.
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