Occurrence of Ips typographus (L.) after wind damage in the Kościeliska Valley of the Tatra National Park

Abstract

Abstract. At the end of 2013, Norway spruce stands in the area of the Tatra National Park were severely damaged by strong storms especially in the Kościeliska Valley region. In the following spring of 2014, a survey recording the occurrence of the spruce bark beetle Ips typographus (Coleoptera, Curculionidae, Scolytinae) was initiated in order to describe the dynamics of beetle reproduction in relation to protection measures executed in wind-damaged stands. Ten research plots with 20 trees each were established in a socalled active protection zone, where the broken and fallen trees had been processed and removed in 2014, and in a passive protection zone, where no actions were taken, and the dynamics of Norway spruce mortality due to bark beetle infestation including quantitative parameters (infestation density, sex ratio of beetle populations) were examined. The entomological analyses were performed on 25 × 25 cm large bark samples taken from four (active zone) or two (passive zone) tree sections.In the first year of the survey, no infested standing trees were recorded on the plots and the colonisation of fallen and broken trees was very weak. In the second year (2015), infestations appeared in larger numbers on the plots with passive compared to active protection but the infestation density was 0.89 mating chambers per 1 dm 2 regardless of the protection status. In the third year (2016), most of the remaining living spruces had been infested with a mean density of 0.82 m.ch. per 1 dm 2 . In 2015, the proportion of females in the beetle population was 65.8% being higher in the active (68.4%) than the passive (64.0%) protection zone, while in 2016 the proportion was 63.5% and in this case slightly higher in the passive protection zone (63.9% as compared to 63.2%).These results are in accordance with patterns observed in wind-damaged Norway spruce stands of other areas in Poland and Europe and demonstrate the usefulness of forest management procedures in mitigating I. typographus outbreaks.

Reproduction abilities of Ips typographus (L.) (Coleoptera: Curculionidae, Scolytinae) in the stands damaged by the wind in 2013 in the Kościeliska Valley (Tatra National Park)

“…The high share of the gallery systems with 2 females indicates high reproduction potential of beetles attacking standing trees. On the other hand, the reproduction success, relatively high in the first year of the investigations (and also first year of the outbreak), collapsed in the next years to the level incomparable with previous studies, which is a phenomenon that is difficult to explain, especially taking into account the abundance of stressed trees, which is favourable for I. typographus reproduction (Grodzki et al 2014;Grodzki and Gąsienica Fronek 2017). Possible reason of this collapse seems to result from long-lasting drought that can enhance the development of pre-imaginal stages, but -at the same time -decrease the quality of cambium, as moderate water stress (limiting growth but not photosynthesis) increases the production of carbonbased secondary metabolites (i.e.…”

“…-Contrarily to the other cited results, our data were collected exclusively from standing, living trees with still functioning (although sometimes reduced) defence mechanisms. Taking into account the described population features, very intense tree mortality (Grodzki and Gąsienica Fronek 2017) and mechanisms known from the other wind events (Grodzki and Guzik 2009), further development of the outbreak can be expected in this area.…”

“…Lower reproduction success in the Kościeliska Valley (in comparison with the field data from the other localities) most probably results from less favourable thermal conditions on higher altitudes (cf. Grodzki and Gąsienica Fronek 2017) and relatively high infestation density on standing trees, necessary to overcome their defence mechanisms (Christiansen et al 1987). This density, acting as an important factor that negatively affects the length of maternal galleries and oviposition (Anderbrant 1990, Weslien 1994, Grodzki et al 2014, was much higher than 0.5 -the level optimal for I. typographus reproduction (Schopf and Köhler 1995).…”

“…(Grodzki and Gąsienica Fronek 2017). The numbered trees were examined during 3 growing seasons (2015)(2016)(2017) in order to determine the spruces recently infested by bark beetles, which actually developed under the bark.…”

“…tion level of the spruce bark beetle Ips typographus (L.) and related infestations of standing trees were observed (Grodzki and Gąsienica Fronek 2017). Such opportunity enabled the survey on the reproduction abilities of I. typographus population in the mountain environment offering favourable breeding conditions.…”