Shepperd & Guyon

    Shepperd & Guyon

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    Wayne D. ShepperdJohn GuyonMassive aspen die-off in the western U.S.: What is going on?

    Wayne D. Shepperd, USDA-FS Rocky Mountain Research Station, Fort Collins, CO, and John Guyon, USDA-FS State and Private Forestry, Ogden, UT

    Aspen die-off differs from normal aspen vegetative succession or decline in that mature trees die quickly within a year or two and no new sprouting occurs as a result. Lack of sprouting may indicate that lateral roots are also dead, preventing aspen from re-occupying the site. Die-off seems to begin in epicenters and spread radially through an affected aspen stand. Stands on all topographic positions, moisture regimes, and soil types are affected, and the phenomenon has been reported throughout the west from Arizona into Alberta. Die-off can affect one clone and leave other nearby clones untouched. Younger age classes and advanced regeneration are often not affected to the same extent as mature overstory trees in the same clone. Cytospora cankers, poplar borers, and other damage or stress agents are often associated with die-off epicenters.

    Our presentation will discuss factors that may be associated with aspen die-off and present potential hypotheses to be investigated in multidisciplinary research to identify causal agents or environmental factors contributing to aspen die-off and determine whether possible management options exist to reduce the risk of die-off, or loss of parent roots.

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