Scholarlink

<p>Changes in the hydrological regime have strongly influenced mesophilic conifers throughout the boreal zone. We studied the growth and vitality of fir trees and regeneration within the zone of <i>Abies</i> <i>sibirica</i> Ledeb. dieback in the Eastern Sayan and Kuznetsk Alatau Mountains, Siberia. The peak of fir mortality occurred in 2013–2018, leading to the dieback of approximately 75% of fir-dominant forests. This catastrophic fir mortality was triggered by an anomalous drought in 2012 (inciting factor) and a massive outbreak of the bark beetle <i>Polygraphus proximus</i> Blandford, an invasive species previously not found in Siberia (contributing factor). Fir mortality was predisposed by chronic water stress since the onset of warming. In the mixed forests (with aspen or birch), most fir survived bark beetle attacks. Fir undergrowth also mainly survived due to atmospheric drought mitigation by the overstory canopy. In response to beetle attacks, trees formed “physical-chemical barriers” within tree rings which consist of closed rows of resin-containing ducts and lignified xylem. Surviving trees showed a marked increase in growth. The elevational limit of the <i>P. proximus</i> range coincides with that of the fir range (c. 1440&#xa0;m a.s.l.), where the insect feeds on felled and weakened trees, whereas the outbreak limit is approximately 700&#xa0;m a.s.l. In the Siberian taiga, <i>P. proximus</i> has displaced its rival <i>Monochamus urussovi</i> Fischer, formerly the primary enemy of <i>Abies sibirica</i>. Currently, viable fir regeneration (c. 2800 stems/ha) is potentially sufficient for successful recovery in the primary mortality areas. However, the expected increase in moisture deficit, combined with acute droughts and subsequent outbreaks of <i>P. proximus</i>, will lead to cycles of fir mortality and partial recovery during the twenty-first century. <i>P. proximus</i> is considered as a potential invader into European fir forests. The observed fir dieback is a part of the broader phenomenon of range contraction of mesophilic species (<i>Pinus sibirica</i> Du Tour<i>, </i><i>Picea obovata</i> Ledeb.) in southern Siberia.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Drought and bark beetle synergy: unprecedented fir dieback in the Siberian Taiga

  • 期刊论文

  • 发表日期：

    2026年4月27日

查看全文
  • Viacheslav I. Kharuk,
  • Il’ya A. Petrov,
  • Sergei T. Im,
  • Denis A. Demidko,
  • Maria L. Dvinskaya,
  • Alexander S. Shushpanov

摘要

Changes in the hydrological regime have strongly influenced mesophilic conifers throughout the boreal zone. We studied the growth and vitality of fir trees and regeneration within the zone of Abies sibirica Ledeb. dieback in the Eastern Sayan and Kuznetsk Alatau Mountains, Siberia. The peak of fir mortality occurred in 2013–2018, leading to the dieback of approximately 75% of fir-dominant forests. This catastrophic fir mortality was triggered by an anomalous drought in 2012 (inciting factor) and a massive outbreak of the bark beetle Polygraphus proximus Blandford, an invasive species previously not found in Siberia (contributing factor). Fir mortality was predisposed by chronic water stress since the onset of warming. In the mixed forests (with aspen or birch), most fir survived bark beetle attacks. Fir undergrowth also mainly survived due to atmospheric drought mitigation by the overstory canopy. In response to beetle attacks, trees formed “physical-chemical barriers” within tree rings which consist of closed rows of resin-containing ducts and lignified xylem. Surviving trees showed a marked increase in growth. The elevational limit of the P. proximus range coincides with that of the fir range (c. 1440 m a.s.l.), where the insect feeds on felled and weakened trees, whereas the outbreak limit is approximately 700 m a.s.l. In the Siberian taiga, P. proximus has displaced its rival Monochamus urussovi Fischer, formerly the primary enemy of Abies sibirica. Currently, viable fir regeneration (c. 2800 stems/ha) is potentially sufficient for successful recovery in the primary mortality areas. However, the expected increase in moisture deficit, combined with acute droughts and subsequent outbreaks of P. proximus, will lead to cycles of fir mortality and partial recovery during the twenty-first century. P. proximus is considered as a potential invader into European fir forests. The observed fir dieback is a part of the broader phenomenon of range contraction of mesophilic species (Pinus sibirica Du Tour, Picea obovata Ledeb.) in southern Siberia.