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Mountain pine beetle impacts to lodgepole pine forests

Posted date: January 23, 2015
Publication Year: 
Authors: Hubbard, Robert M.;
Document type: Briefing Papers


Aerial view of tree mortality from mountain pine beetle outbreak.
Aerial view of tree mortality from mountain pine beetle outbreak.
The recent mountain pine beetle (Dendroctonous ponderosae, MPB) outbreak in North American lodgepole pine (Pinus contorta) forests demonstrates the importance of insect related disturbances in changing forest structure and ecosystem processes. Phloem feeding by beetles disrupts transport of photosynthate from tree canopies and fungi introduced to the tree’s vascular system by the bark beetles inhibit water transport from roots to canopy. The implications of these processes for tree mortality are poorly understood.

Key Findings:

  • The current MPB epidemic has impacted more than 4 million acres throughout much of western North America, raising concerns about future forest structure.
  • Long-term consequences of the MPB outbreak will shift tree species composition in forests and influence timber and water production, wildfirebehavior, wildlife habitat and other forest attributes.
  • Rapid decline in transpiration rates and leaf water potential in lodgepole pines following MPB attack suggests that changes in foliar moisture will have important implications for fire risk and behavior within weeks of bark beetle infestation.
  • The magnitude of impacts will depend on the severity of infestation and changes to stand structure and climate.

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