Abstract
The most devastating insect invasion of forest ecosystems in Russia is the recent mass reproduction of the four-eyed fir bark beetle (Polygraphus proximus Blandf.) in southern Siberian fir (Abies sibirica Ledeb.) forests. The objective of our research was to study the spatial structure of fir forests and their change under the impact of the four-eyed fir bark beetle in its secondary (invasive) distribution range. We selected two fir stands located near the villages of Itatka and Malinovka in the Tomsk region. Both stands represent natural ripe succession forests on sites that previously experienced logging activities, which were triggered by settlement activities in the second half of the nineteenth century. We used Field-Map technology for gathering non-spatial and spatial stand data. The analysis showed that height, diameter and radial increment of fir trees, killed or severely weakened by attacks of the four-eyed fir bark beetle, were significantly lower than that of healthy individuals. The social status of fir trees, seriously attacked or already killed by Polygraphus proximus was indicated by the Ui index as moderately suppressed. In contrast to the distribution pattern of living firs, the pattern of dead or severally weakened firs killed by the four-eyed fir bark beetle was significantly clumped over short distances (sample plots (SP) Itatka and Malinovka). This finding coincides with visual observations in other stands, that dead trees are grouped to some extent. However, the hypothesis of spatial independence of the tree positions of living and dead firs was accepted for both plots.Funding: The research was funded by the Russian Foundation for Basic Research and the government of Tomsk region, grant No. 16-44-700782, and carried out as part of a state assignment of the Center for Forest Ecology and Productivity of the Russian Academy of Sciences (No. АААА-А18-118052400130-7).For citation: Debkov N.M., Gradel A., Aleinikov A.A. Reconstruction of Stand History and Impact Evaluation of an Invasive Bark Beetle in Siberian Fir Forests with the Help of Spatial Structure Analysis. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 3, pp. 24–41. DOI: 10.37482/0536-1036-2020-3-24-41
Highlights
IntroductionThe beginning of the twenty-first century is accompanied by massive cases of invasions of alien biota [6]
According to Kharuk et al [26] the progressive spread of the aggressive beetle Polygraphus proximus in Siberia is associated with the impact of climate change
The tree status of each fir tree was evaluated according to a six-point scale, which describes the impact of Polygraphus proximus on Abies sibirica
Summary
The beginning of the twenty-first century is accompanied by massive cases of invasions of alien biota [6]. In addition long-term modeling shows an increase in the number of invasions [5]. The most devastating invasions in Russia are invasions of the box tree moth Cydalima perspectalis [1], emerald ash borer Agrilus planipennis [43] and four-eyed fir bark beetle Polygraphus proximus [28]. The latter one is denoted as the Far Eastern bark beetle invasion due to its original distribution area. In terms of scale and risks for Russian forest management, the invasion of this insect is the most significant in Siberia, where it first occurred in 2008 [28]. Its mass reproduction is promoted by the weakening of forests by water stress due to the increasing climate aridisation [25]
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