Characteristics of Norway spruce trees (Picea abies) surviving a spruce bark beetle (Ips typographus L.) outbreak

Abstract

The characteristics of spruce individuals, which survived a massive bark beetle outbreak, were compared with the characteristics of neighbouring attacked trees in Š umava National Park (Czech Republic). Selected parameters related to crown geometry, stand conditions and distances between trees were measured or estimated. Significant differences were found between the surviving trees and the neighbouring trees attacked by I. typographus. Trees with a higher level of stem shading (longer crown length) tended to survive. The attacked trees were usually located in areas with larger basal area, especially southwards from them. A shorter distance to a previously attacked tree increased the probability of additional attack. Spruce trees with more progressive crown structure transformation (primary structure defoliation) were significantly more frequently attacked by spruce bark beetle. Superior and taller trees had a clearly longer life expectancy than dominant ones. These results show that the attack of trees by bark beetle can be predicted to a certain degree, which can be used in management of endangered spruce forests.

Tree and stand-level patterns and predictors of Norway spruce mortality caused by bark beetle infestation in the Tatra Mountains

“…These results correspond to landscape-level analyses on the role of topography, which suggest that south-facing forest edges are more stressed and south-facing trees are killed sooner and more frequently during outbreaks (Powers et al, 1999;Jakuš et al, 2011;Kautz et al, 2013). Moreover, bark beetle larvae develop much faster on warmer, sun-exposed south-facing slopes, resulting in more generations produced per year (Stadelmann et al, 2013).…”

Differences in transpiration of Norway spruce drought stressed trees and trees well supplied with water

“…Overheating of tree capillaries on the stem by sun radiation can also affect water transpiration, causes water stress and results in predisposition for bark beetle attacks (Jakuš et al 2011). In June 2003, Gartner et al (2009) Lagergren & Lindroth (2002) state that in the period of extreme drought some spruce trees did not transpire at all.…”

Transition from windfall- to patch-driven outbreak dynamics of the spruce bark beetle Ips typographus

“…Both the volume and age of available host trees are important determinants for bark beetle infestations (Worrell, 1983;Klutsch et al, 2009;Jakuš et al, 2011;Kärvemo et al, 2014b). The spruce bark beetle does for example prefer mature spruce stands, and attack risk is positively correlated with the standing volume of spruce trees per hectare, up to a level corresponding to the standing volume in a mature forest (Kärvemo et al, 2014b).…”

“…Similarly, steepness was probably not an important determinant of variation in patch size, since almost all the stands available for attack during the expansion phase of the outbreak (2007)(2008)(2009) were in hillsides with similar steepness. More geographically fine-scaled predisposing factors for bark beetle attack include aspect (Worrell, 1983;Stadelmann et al, 2014), soil conditions (Worrell, 1983;Klutsch et al, 2009), stand vigor (Coops et al, 2009), and sudden stress (Führer et al, 1997) operating at the stand or tree-group level, and nutrient content, tree vigor, defense capacity, and drought stress (Reid and Robb, 1999;Hedgren and Schroeder, 2004;Wallin and Raffa, 2004;Coops et al, 2009;Jakuš et al, 2011;Schiebe et al, 2012;Netherer et al, 2015) operating at the individual tree level. Unfortunately, there are no data available to test the influence of such fine-scale factors on the extent of infestation patches in our study area.…”