Attacks by bark- and wood-boring Coleoptera on mechanically created high stumps of Norway spruce in the two years following cutting

Attacks of bark- and wood-boring beetles on mechanically created high stump s of Norway spruce, Picea abies L. (Karst.), were studied in the provinces of Dalarna (Grangarde area) and Uppland (Fageron) in central Sweden. The ex periment included a total of 362 stumps in the Grangarde area as well as 48 stumps and 18 logs at Fageron. Most inspections were conducted in the firs t and second autumns following the cuttings made to create the stumps. All stumps were attacked by at least one species during the two-year period, an d for almost all of them (95%) the initial attacks occurred in the first su mmer. The most frequently encountered species on the stumps were the scolyt ids Ips typographus (L.), Pityogenes chalcographus (L.), Hylurgops palliatu s (Gyll.), Orthotomicus spp., Trypodendron lineatum (Oliv.), Dryocoetes sp. and Polygraphus poligraphus (L.), and the cerambycids Tetropium spp. and M onochamus sutor (L.). Both the time of cutting and stump diameter influence d beetle colonisation. I. typographus was not found in autumn-cut stumps, w hile Orthotomicus spp. was found more frequently in autumn-cut stumps than in spring-cut stumps. There was a positive relationship between I. typograp hus occupancy and stump diameter, while negative relationships were found b etween stump diameter and H. palliatus and T. lineatum occupancy. Most stum ps (ca. 80%) were attacked by more than one bark- and wood-boring species i n the first summer. The proportion of stumps attacked was significantly hig her than the proportion of logs attacked for P. poligraphus, I. lineatum an d Tetropium spp., whereas the opposite was true for I. typographus. The per centage of bark area utilised by I. typographus was significantly higher in logs than in stumps. (C) 1999 Elsevier Science B.V. All rights reserved.