Climate affects severity and altitudinal distribution of outbreaks in an eruptive bark beetle

Abstract

Temperature warming and the increased frequency of climatic anomalies are expected to trigger bark beetle outbreaks with potential severe consequences on forest ecosystems. We characterized the combined effects of climatic factors and densitydependent feedbacks on forest damage caused by Ips typographus (L.), one of the most destructive pests of European spruce forests, and tested whether climate modified the interannual variation in the altitudinal outbreak range of the species. We analyzed a 16year time-series from the European Alps of timber loss in Picea abies Karsten forests due to I. typographus attacks and used a discrete population model and an information theoretic approach to compare multiple competing hypotheses. The occurrence of dry summers combined with warm temperatures appeared as the main abiotic triggers of severity of outbreaks. We also found an endogenous negative feedback with a 2-year lag suggesting a potential important role of natural enemies. Forest damage per hectare averaged 7-fold higher where spruce was planted in sites warmer than those within its historical climatic range. Dry summers, but not temperature, was related to upward shifts in the altitudinal outbreak range. Considering the potential increased susceptibility of spruce forests to insect outbreaks due to climate change, there is growing value in mitigating these effects through sustainable forest management, which includes avoiding the promotion of spruce outside its historical climatic range.

Composition and Elevation of Spruce Forests Affect Susceptibility to Bark Beetle Attacks: Implications for Forest Management

“…Large I. typographus outbreaks were observed mainly in sites with environmental conditions not fully suitable for spruce. Recent studies carried out on the south-eastern Alps show, for instance, a mean damage per hectare about seven times higher in spruce forests growing in sites warmer than those within the natural climatic range of spruce [19]. Moreover, the intensity and altitudinal distribution of the insect outbreaks were affected by dry summers, which were related to an increase of the mean damage [17] and an upward shift of the altitudinal outbreak range [19].…”

“…In the last few years, the spruce bark beetle, Ips typographus (L.), one of the most destructive insects infesting spruce forests (Picea abies Karsten), caused serious damage almost everywhere in Europe [3,[11][12][13]. Severe damage was also recorded in spruce forests growing on the Southern Alps [14][15][16][17][18][19]. Large I. typographus outbreaks were observed mainly in sites with environmental conditions not fully suitable for spruce.…”

Scolytus koenigi Schevyrew, 1890 (Coleoptera: Curculionidae): new bark beetle for the Czech Republic and notes on its biology

“…Alternatively, this finding of S. koenigi in the Czech Republic might be evidence of the range expansion to the north, possibly reflecting global climate change, as has been documented for many other animal species (Quante 2010), including several saproxylic beetles whose survival rates have increased on the borders of their northern ranges (e.g. Logan, Powell 2001;Bentz et al 2010;Marini et al 2012;Buse et al 2013). However, the exact temperature requirements of S. koenigi are not known to support this hypothesis.…”

Assessing the Suitability of Future Multi- and Hyperspectral Satellite Systems for Mapping the Spatial Distribution of Norway Spruce Timber Volume

“…However, the compatibility between timber volume maps produced by EnMAP and Sentinel-2 largely facilitates an integration of both products without the need to develop individual processing concepts. Due to its hyperspectral coverage, EnMAP is expected to contribute complementary information on the biophysical condition of Norway spruce, such as indicators of increasing drought stress and insect calamities (e.g., bark beetle attacks) [79], which are expected to increase because of regional warming trends [80,81]. Since both information levels are important for optimizing economically viable and ecologically balanced management strategies, we expect that Sentinel-2 and EnMAP, once both are operational, can be used in synergy.…”