Smuggler Mountain Verbenone Project

In 2009, forest land managers collaborated in an area-wide treatment to reduce tree mortality resulting from mountain pine beetle (MPB) attack over ca. 270 acres in the Roaring Fork Valley near Aspen, CO using a combination of pheromone applications and removal of infested brood trees.  The three treatments were (1) application of verbenone pouches combined with brood tree removal; (2) application of verbenone flakes combined with brood tree removal; and (3) untreated reference stands.  Efficacy was assessed by conducting post-season timber cruises to measure stand structure and pre- and post-treatment MPB attack rates.  There were unavoidable differences between plots in the amounts of pheromone applied, pre-treatment MPB attack rates, and existing forest structure, which is known to influence bark beetle risk.  This project was designed as an individual case study without replication of treatments.  We used logistic regression techniques to assess differences in beetle attack rates and the influence of environmental conditions, including pheromone treatments, on the probability (risk) of MPB attack.  We also used conventional general linear models where appropriate. 

Our key findings were:

·       Failure to remove infested brood trees drastically increased the localized risk of MPB mass attack (by an average of nearly forty-fold).  This finding cannot be extrapolated  stand-wide, but suggests that brood tree removal is crucial for minimizing MPB damage.

·       The risk of MPB attack increased with stand density, as we had predicted; stand structure has previously been shown to play a key role in bark beetle outbreaks.

·       The risk of MPB attack in verbenone-treated stands was significantly lower than in untreated stands; the risk of MPB attack was slightly less with flakes than with pouches, but the difference between them was not statistically significant.


For the full Smuggler Mountain Verbenone & Brood Tree Removal Report, please click on the link below.

Smuggler Mountain Verbenone & Brood Tree Removal - Final Report

 

Prepared for ACES by:
Nancy Gillette, Principal Investigator, USDA FS, PSW Research Station, Albany, CA
William Murray, Project Manager, San Jose State University, San Jose, CA
Maggi Kelly, Geospatial Lead; David Wood, Pheromone Lead, Dept. Environmental Science, Policy, and Management, University of California, Berkeley, CA
Jeff Webster, Forestry Lead, J. Webster Forestry Consulting, Redding, CA
Sylvia Mori, Statistics Lead, USDA FS, PSW Research Station, Albany, CA