By: Melanie Vanderhoof PhD
We often hear about the impacts of invasive species on local environments. However, an organism does not need to be invasive or large to have drastic effects at a landscape level. Mountain pine beetle (MPB) outbreaks in the south central Rocky Mountains exemplify the far-reaching effects that one small native species may have on entire ecosystems. Dr. Melanie Vanderhoof, currently an ORISE post-doctoral research fellow at the Environmental Protection Agency, investigated the impacts of these outbreaks on long-term energy and water fluxes in coniferous forests in Colorado and Wyoming. These variations to climate patterns can last for more than 40 years and coupled with global climate change, the dynamics of these outbreaks may also be altered.
During non-epidemic years the MPB is typically unable to kill healthy trees. However, recent winters in the Rocky Mountains have been warmer while summers have been both warmer and dryer. These changes in climate increased stress on evergreen trees and left them vulnerable to MPB attack. Female adult beetles carrying blue fungus stain channel under the bark of a healthy, but stressed, tree. The fungus from the MPB blocks the transport of water and nutrients within the tree and prevents the tree’s defense against the beetle invaders. The beetles mate, lay eggs, and when the eggs hatch, the MPB larvae burrow further into the tree. The MPB pupates, and the young adults continue to feed in the tree, becoming contaminated by the blue stain fungus. The contaminated adults then leave the tree and infect a new tree close by. The life cycle of the MPB is generally one year, but may be up to two years in high elevation environments.
If you are interested in reading more about Dr. Vanderhoof’s work, the links to two of her papers are below, and be on the lookout for a third that is in press!
Vanderhoof, M., C.A. Williams, B. Ghimire, & J. Rogan. 2013. Impact of mountain pine beetle outbreaks on forest albedo and radiative forcing, as derived from Moderate Resolution Imaging Spectroradiometer, Rocky Mountains, USA. Journal of Geophysical Research: Biogeosciences 118: 1461-1471.
Vanderhoof, M., C.A. Williams, Y. Shuai, D. Jarvis, D. Kulakowski, & J. Masek. 2014. Albedo-induced radiative forcing from mountain pine beetle outbreaks in forests, south-central Rocky Mountains: magnitude, persistence, and relation to outbreak severity. Biogeosciences 11: 563-575.
Vanderhoof, M. & C.A. Williams. In press. Persistence of MODIS evapotranspiration impacts from mountain pine beetle outbreaks in lodgepole pine forests, south-central Rocky Mountains. Agricultural and Forest Meteorology.