As the Krasnoyarsk scientists have found out, Siberian pine and fir are dying due to climate change and increased activity of insect pests. An increase in the mortality rate of Siberian stone pine and fir in the taiga forests has been observed since the beginning of the 21st century. The scientists have determined that the death of these moisture-loving dark conifers is associated with the deterioration of moisture supply due to climate warming.
The activation of insect pests, whose attacks are facilitated by the weakening of trees by water stress and periodic droughts, contributes to the increase in the mortality of dark conifers. According to forecasts, the increasing frequency and intensity of droughts may lead to the disappearance of dark conifers in the southern parts of their growing area. The research results are published in the journal Global Ecology and Biogeography.
The dark coniferous Siberian taiga, formed by Siberian pine, fir and spruce, extends from the border with Mongolia to the Arctic Circle. Numerous international studies in boreal forests indicate an increase in the mortality of conifers in recent decades. However, the exact reasons for the death of trees, its connection with geographic and climatic features are not always known.
The scientists of the Federal Research Center "Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences" used materials from satellite monitoring, ground-based research and climate data to identify the main reasons for the drying up of Siberian pine and fir. The researchers found that in the 21st century, the area of the dead fir and pine stands was 4% and 7.5%, respectively. The drying out of moisture-loving dark-coniferous stands, observed mainly in the southern part of their growing area, is associated with deterioration in moisture supply and attacks of insect pests that affect weakened trees.
Interesting data was obtained when analyzing the radial growth of the trees. It turned out that the warming of the climate since the 1970s has stimulated the growth of the trees. However, a further increase in air temperature led to water stress and a decrease in growth, followed by the drying up of some trees under the influence of droughts and pests.
The main pest of the fir is Polygraphus proximus Blandford – fir bark beetle, the mass spread of which was not previously noted in the Siberian taiga. The pine and fir stands are damaged by their traditional enemy – the Siberian silk moth, whose outbreaks have intensified in recent decades, and the zone of damage has expanded due to climate warming.
"The results show that with the predicted increase in climate aridity, the growing area of Siberian pine and fir in the southern low-elevation parts of Siberia will decrease with the likely replacement of these moisture-loving species with less moisture demanding species, such as pine and larch," said the Doctor of Biological Sciences, Head of the Forest Monitoring Laboratory of “Sukachev Institute of Forest SB RAS”, professor of SFU Vyacheslav Kharuk.
The research was supported by the Russian Foundation for Basic Research and the Krasnoyarsk Regional Science Foundation.
Information provided by Krasnoyarsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences