Effect of bark beetle (Ips typographus L.) attack on bark VOC emissions of Norway spruce (Picea abies Karst.) trees

Climate warming driven storms are evident causes for an outbreak of the European spruce bark beetle (Ips typographus L.) resulting in the serious destruction of mature Norway spruce (Picea abies Karst.) forests in northern Europe. Conifer species are major sources of biogenic volatile organic compounds (BVOCs) in the boreal zone. Climate relevant BVOC emissions are expected to increase when conifer trees defend against bark beetle attack by monoterpene (MT)-rich resin flow. In this study, BVOC emission rates from the bark surface of beetle-attacked and non-attacked spruce trees were measured from two outbreak areas, litti and Lahti in southern Finland, and from one control site at Kuopio in central Finland. Beetle attack increased emissions of total MTs 20-fold at litti compared to Kuopio, but decreased the emissions of several sesquiterpenes (SQTs) at litti. At the Lahti site, the emission rate of alpha-pinene was positively correlated with mean trap catch of bark beetles. The responsive individual MTs were tricyclene, alpha-pinene, camphene, myrcene, limonene, 1,8-cineole and bornyl acetate in both of the outbreak areas. Our results suggest that bark beetle outbreaks affect local BVOC emissions from conifer forests dominated by Norway spruce. Therefore, the impacts of insect outbreaks are worth of consideration to global BVOC emission models. (C) 2015 Elsevier Ltd. All rights reserved.