The European spruce bark beetle Ips typographus (L.) in wind-damaged stands of the eastern part of the Tatra National Park – the population dynamics pattern remains constant

摘要

In March 2017, in the eastern part of the Tatra National Park in Poland, large windthrowns affected the passively and actively protected Norway spruce Picea abies stands. In early 2018, a set of 12 small research plots (20 trees on each plot) was established in the Norway spruce stands next to the windblown area – 6 in the stands under active nature protection (broken and fallen trees processed in 2017), and 6 in the stands under passive nature protection (trees left on the ground). Living trees on the plots were regularly checked during the growing season in order to identify and register the spruces infested by Ips typographus, which were dissected in 2 or 4 half-meter sections. 155 spruces (64%) infested by I. typographus were recorded on all 12 plots: 118 out of 120 (98%) in passive and 37 out of 120 trees (31%) in active protection. Mean infestation density calculated on 128 samples from 47 trees was higher under passive than under active protection (1.23 and 0.92 mating chamber per 1 dmsup2/sup, respectively). Among 1709 gallery systems, those with 2 maternal galleries prevailed (63.0%); the mean share of females was higher in passive than in active protection zone (63.1 and 59.6% respectively). The mean number of progeny per one female was higher in active than in passive protection zone (20.23 and 19.12 respectively). I. typographus attack on standing trees had lower intensity in the stands previously subjected to the processing and removal of fallen and broken trees, which indicates positive effect of implemented active protection procedures. The parameters describing I. typographus population on attacked trees, as well as low activity of natural enemies, demonstrate its reproduction potential and resulting high risk of a new outbreak, according to the pattern known earlier from the other areas in Poland and Europe.