Photo: Ziehaus
Bark Beetle Situation
The bark beetle has survived the winter quite well and is now threatening the protection forest
Infestation mainly in high stands up to the tree line
The strategy to combat the bark beetle and specific hazards for the year 2008 were discussed at the annual meeting of forest protection experts. Thereby, experts from Austria met with their colleagues from the neighbouring countries to discuss transnational strategies.
The enormous snow quantities and low temperatures helped rather than hurt the bark beetles (especially the printer beetle). Although they breed in the bark, they hibernate on the ground. They can withstand dry cold of up to -20 degrees for longer periods, but wetness and cold is a dangerous and fatal combination for the beetles. The high snow cover protected them from enemies such as the woodpecker, and also provided insulation from cold and wet.
Many beetle-infested trees are not discovered until the snow-melt in spring, and the main flight from this hibernation takes place during the next longer period of good weather. Then, all the beetles fly at the same time and the infestation pressure cannot be lowered by combating measures. The changeable and cold weather in spring delayed this attack a little, gaining valuable time. Because these winter beetles can form 2 - 3 sibling broods and should therefore be skimmed off with bait trees. As a result of the moist summer, the damage caused by this first generation is only now becoming visible and the volume of damaged wood is difficult to assess.
Not all of the wind-throw caused by the foehn storm of spring 2008 could be removed, and the remaining wood was infested more strongly by the bark beetle. Due to the extremely warm and dry weather in last summer, stands at all altitudes were also infested locally by the printer beetle and the copper engraver. Although the last year did not offer particularly favourable weather conditions for the bark beetle, the level of infestation continued to rise. An increased incidence of the larch bark beetle and the small, 8-toothed spruce bark beetle was also observed in the higher stands. As a result of enormous efforts to remove the infested wood from the forest, a lot of the damage has been contained. In 2004 there was a strong base population again, though, resulting in a continuation of the beetle calamity.
Therefore a lot of beetle-infested wood were registered in 2007, especially in the regions of Upper Austria, Styria and Salzburg hit by foehn storms. In Lower Austria the volume of infested wood was reduced by one third through effective combat measures. Detailed information can also be found on the homepage of the Federal Office and Research Centre for Forests: In addition to the bark beetle calamity, an increased incidence of the processionary caterpillar, the black arches moth, the pine shoot moth, the fir sawfly and the fungus Phytophtera was registered.
Therefore, all the provinces have again initiated effective combating measures in 2007, such as the use of bait trees, processing and removal or chipping and mulching of infested material. Since the identification of new infestation is an important aspect, specially trained personnel has been trained and employed in the observation of stand infestation. The BFW enters the weekly bark beetle figures from some 140 pheromone traps in seven provinces into a database and this monitoring provides an overview of the threatened regions in Austria to the forest owners.
In addition to these technical combating measures, attention is paid to forest hygiene and the immediate stripping and removal of infested material. The local authority not only provides information and advice for the forest owners concerned, but also has to make sure that its orders are actually carried out. The promotion of forest protection activities varies from one province to another, and like the BFW’s bark beetle monitoring, information about this can be found on the relevant Internet sites.
25.06.2008,