Distribution of Norway spruce bark and wood-boring beetles along Alpine elevational gradients

Temperature is probably the most important driver of insect response to climate change and has many implications at both individual and population levels. The present study explored how elevation, as a proxy for temperature, affects the abundance and diversity of bark and wood-boring beetles associated with Norway spruce (Picea abies) along its southern range. We selected three elevational gradients (approximately 900-1500 m) in spruce stands in the south-eastern Alps, each consisting of four locations. From April to September 2011, four traps of different types were installed at each location: three baited with generic lures (alpha-pinene and ethanol) and one baited with a pheromone specific for Ips typographus. In addition, three fresh spruce logs were exposed on the same locations. Species richness did not vary significantly with elevation, whereas the abundance of most individual species did. Generally, aggressive species responded positively to higher temperature, whereas most non-aggressive species responded negatively. In a warming scenario, it is likely that spruce forests will face increasing damage from aggressive species. This will threaten the growth and survival of Norway spruce at low elevation, especially at southern latitudes.