Silvicultural control of mountain pine beetle: Prescriptions and the influence of microclimate

Abstract

Inarecent American Entomologist article, Malcolm Furniss (1997) described the profound impact that one insect, the mountain pine beetle, Dendroctonus ponderosae Hopkins, had on the establishment of forest entomology in North America. Unlike other classical examples of depredations by one insect profoundly impacting American entomology (e.g., the Rocky Mountain grasshopper [Walsh] and applied entomology, see An Tn-Depth Look at the Life and Times of C. V. Riley, Smith and Smith 1996), the interest in, and importance of, the mountain pine beetle has remained undiminished during the century following its original description in 1902. The reason for this sustained interest is multifaceted. First, unlike most insects, and even most bark beetles, the mountain pine beetle usually kills its host to reproduce successfully. Second, unlike the Rocky Mountain grasshopper, this widely distributed insect remains very much extant. Mountain pine beetle outbreaks rank among the most impressive of naturally occurring entomological events (Fig. 1). During the last great epidemic in forests of lodgepole pine, Pinus contorta Douglas, from 1979 to 1983, over four million acres per year were infested. These outbreaks resulted in mortality of over 15 million trees each year during the five-year period (McGregor 1985). The resulting fuel loads contributed in large part to a subsequent, equally spectacular, episode of wildfires (Roe and Amman 1970, Brown 1975), including the 1988 Yellowstone fires. Hence, for both economic and ecological reasons, the mountain beetle has remained the subject of intensive research and management since it was first described by Hopkins.