title: Nonstructural carbohydrate dynamics of lodgepole pine dying from mountain pine beetle attack.
abstract: Bark beetle outbreaks are an important cause of tree death, but the process by which trees die remains poorly understood. The effect of beetle attack on whole-tree nonstructural carbohydrate (NSC) dynamics is particularly unclear, despite the potential role of carbohydrates in plant defense and survival. We monitored NSC dynamics of all organs in attacked and protected lodgepole pines (Pinus contorta) during a mountain pine beetle (Dendroctonus ponderosae) outbreak in British Columbia, starting before beetle flight in June 2011 through October 2012, when most attacked trees had died. Following attack, NSC concentrations were first reduced in the attacked region of the bole. The first NSC reduction in a distant organ appeared in the needles at the end of 2011, while branch and root NSC did not decline until much later in 2012. Attacked trees that were still alive in October 2012 had less beetle damage, which was negatively correlated with initial bark sugar concentrations in the attack region. The NSC dynamics of dying trees indicate that trees were killed by a loss of water conduction and not girdling. Further, our results identify locally reduced carbohydrate availability as an important mechanism by which stressors like drought may increase tree susceptibility to biotic attack.
authors.affiliation: Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada.
authors.forename: Erin
authors.initials: E
authors.lastname: Wiley
authors.affiliation: Omineca Research and Stewardship Team, British Columbia Ministry of Forests Lands and Natural Resource Operations, Prince George, BC, V2N 4W5, Canada.
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Rogers
authors.affiliation: Omineca Research and Stewardship Team, British Columbia Ministry of Forests Lands and Natural Resource Operations, Prince George, BC, V2N 4W5, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Hodgkinson
authors.affiliation: Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Landhäusser
mesh_terms: D000818:Animals; D001955:British Columbia; D050260:Carbohydrate Metabolism; D001517:Coleoptera; D060434:Herbivory; D028223:Pinus / Q000502:physiology*; D014197:Trees; D048889:Weevils; D052584:Xylem / Q000378:metabolism
keywords: biotic attack; lodgepole pine (Pinus contorta); mountain pine beetle (Dendroctonus ponderosae); nonstructural carbon; tree mortality; water stress