Insect-fire interactions in Yellowstone National Park: the influence of historical mountain pine beetle (Dendroctonus ponderosae) activity on the spatial pattern of the 1988 Yellowstone fires

Lynch, H.J., Renkin, R.A., Crabtree, R.L. and Moorcroft, P.R.

in: A. Wondrak Biel, ed., Greater Yellowstone Public Lands: A Century of Discovery, Hard Lessons, and Bright Prospects: Proceedings of the 8th Biennial Scientific Conference on the Greater Yellowstone Ecosystem, October 17-19, 2005, Mammoth Hot Springs Hotel,Yellowstone National Park. Yellowstone Center for Resources, Yellowstone National Park, Wyoming, USA, pp. 109-118

2006

We examined the historical record of mountain pine beetle (Dendroctonus ponderosae Hopkins) activity within Yellowstone National Park, Wyoming, for the 25-year period leading up to the 1988 Yellowstone fires (1963– 1986) in order to determine how prior mountain pine beetle activity and resulting tree mortality affected the spatial pattern of the 1988 Yellowstone fires. To obtain accurate estimates of our model parameters, we used a Markov Chain Monte Carlo (MCMC) method to account for the high degree of spatial autocorrelation inherent to forest fires. Our final model included four statistically significant variables: drought, aspect, moderate moun-tain pine beetle activity in 1975, and heavy mountain pine beetle activity in 1975. Of the two major mountain pine beetle outbreaks to precede the 1988 fires, the older outbreak (1971–1976) was significantly correlated with the burn pattern, whereas the more recent outbreak (1980–1983) was not. Although regional drought and high winds were responsible for the overall scale of the event, we concluded that mountain pine beetle activity in the mid-1970s increased the odds of burning ~13.0–15.0% and, along with aspect and spatial variation in drought, contributed to the spatial pattern of burned and unburned areas.