Assessment, Conservation and Sustainable Use of Forest Biodiversity

Conservation and Sustainable Use (sustainable forest management)
Results
Spruce stands
All the injected spruce trees in experimental plots with Roundup injection were dying by late May next year
after injection and nearly all of them attracted bark beetles. Only trees of the smallest size (DBH ≤ 4 cm) were
not attacked or had rare attacks because of their very thin bark and faster drying. The following bark beetle
species were found in the injected trees: Pityogenes chalcographus (L.), Polygraphus poligraphus (L.), Ips
typographus (L.), Ips amitinus (Eichh.), Crypturgus cinereus (Herbst), Pityophthorus micrographus (L.),
Trypodendron lineatum (Oliv.). Pityogenes chalcographus dominated in experimental plots. Bark beetles
avoided attacking the tree stems adjacent to the points of arboricide application but colonised other parts of
the tree stems successfully. Our preliminary conclusion is that the arboricide affected bark beetle attack
behaviour but did not prevent the killed trees from being attacked. Time of tree death influenced bark beetle
species composition and relative abundance. In addition, the weather, the presence of bark beetles and
weakened trees in surrounding stands, and concentration of treated trees seemed to influence bark beetle
attack behaviour. Predaceous insects and parasitoids did not appear to play important roles in regulating the
number of bark beetles the year after injection. A danger of the serious pest Ips typographus (L.) attacking the
larger diameter injected trees is thought to be low. In summary, bark beetles found favourable conditions for
development on injected spruce trees and constructed egg galleries of normal length. Untreated healthy trees
on the experimental plots remained free of attack the year after late summer injection.
In experimental plots with mechanical girdling, the treated spruce trees were dying more slowly. Nevertheless,
they were also attacked by bark beetles, mainly by Pityogenes chalcographus. In addition, Polygraphus
poligraphus and Pityophthorus micrographus were also present. We did not detect bark beetle attack on the
remaining healthy spruce trees in the plots with mechanized thinning. Light natural mortality occurred
among trees (DBH 8 cm were readily attacked by Tomicus piniperda (L.), Tomicus minor (Hart.),
Pityogenes chalcographus, Ips duplicatus (Sahl.), Crypturgus cinereus and Trypodendron lineatum. Pine trees
with DBH < 8 cm were attacked mainly by Hylurgops palliatus (Gyll.), Trypodendron lineatum. Only sporadic
attacks by Tomicus piniperda were seen here in the lower part of the tree stems. Tomicus piniperda avoided
attacking the sides of tree stems adjoining the frills.
Trees in experimental plots with mechanical girdling were dying much more slowly, and only a few of them
had sporadic bark beetle attacks (for example, Tomicus piniperda). These trees had green crown and phloem
next year after treatment at the time of inspection in late May. These trees were partly attacked two years after
treatment by Tomicus piniperda, Tomicus minor, Pityogenes chalcographus, Trypodendron lineatum. Most
trees felled in experimental plots with felling were removed. Several of the felled trees that remained in
experimental plot were not preferred by bark beetles and were only lightly attacked. Bark beetle gallery
distribution was irregular on these trees. No bark beetle attacks were found on the remaining neighbouring
healthy trees and in plots without any treatment.
References
Egorov, A.B. (1989). Method of arboricide injection into stems of trees abroad. Forestry abroad: Express
information. Issue 11. VNIITslesresurs Goskomlesa USSR, Moscow. p. 2-22. (In Russian).
Martynov, A.N., Krasnovidov, A.N., and Fomin, A.V. (1998). Roundup usage in a forest. SPbNIILKh,
St. Petersburg. (In Russian with English summary).
Mozolevskaya, E.G., Kataev, ?.A., and Sokolova, E.S. (1984). Methods of forest stem pest and disease foci survey.
Lesnaya promyshlennost, Moscow. (In Russian).
75