INTRODUCTION 



Lodgepole pine ( Pinus contorta Dougl.) forests provide an important cover type on 

 more than 15 million acres in 11 states in the western United States. These forests 

 serve many purposes such as cover and scenic backdrops for recreational areas; protec- 

 tive cover for watersheds; habitat for game animals; grazing for domestic livestock; 

 and a storehouse of raw material for lumber, poles, posts, and pulpwood. But without 

 protection and management these forests are transient pioneers giving way to natural 

 forces such as insects, disease, and in the absence of wildfire, to succeeding vegeta- 

 tion. Maintenance of lodgepole pine forests requires both a greater understanding of 

 the continuing biological processes and a high level of management. 



Historically, the mountain pine beetle, Dendroctonus ponderosae Hopk. has infested 

 extensive areas of lodgepole pine and probably has been active in the ecosystem as long 

 as there have been lodgepole pine trees. Thome (1935) uncovered evidence of several 

 early outbreaks including one that was active in the Horse Creek territory in Utah over 

 180 years ago. He reported other outbreaks occurring in different areas between the 

 year's: 1870 and 1880; 1915 and 1917; 1924 and 1925; 1929 and 1932. 



Flint (1924) reported an epidemic between 1914 and 1918 in lodgepole pine stands 

 near Monture Ranger Station, Lolo National Forest, Montana. 



Beginning in 1909, a small mountain pine beetle outbreak was reported on the 

 Flathead National Forest in the northern Rockies.""" During a succeeding period of 25 to 

 50 years, new infestations appeared in the Rocky Mountains and increased to epidemics 

 on the National Forests and Parks and extended as far south as the Cache National 

 Forest in Utah despite some direct control efforts along the way. Infestations were 

 recorded on the Flathead, Lolo, Bitterroot, Beaverhead, Gallatin, Targhee, Teton, 

 Bridger, Cache, and Caribou National Forests and Yellowstone and Teton National Parks. 

 The infestation was considerably reduced, particularly on the northern forests, when 

 extremely low temperatures in December 1932 and again in February 1933 caused high 

 mortality in overwintering broods. 



Another extensive beetle outbreak is currently in progress in a number of the 

 Intermountain forests where many extensive stands have reached a high state of suscep- 

 tibility to beetle attack. Direct control efforts to contain the beetle populations 

 have met with variable success and extensive tree mortality has occurred. 



One of the primary si Ivicultural problems is how to manage lodgepole pine in the 

 face of constant beetle pressure and recurring tree mortality. The objective and scope 

 of this paper is to explore the role of the mountain pine beetle as an ecological agent 

 in lodgepole pine stands primarily in the Teton, Targhee, and Bridger National Forests 

 and in the Yellowstone and Teton National Parks; also, the study points out some research 

 needs and management alternatives. 



ROLE OF THE MOUNTAIN PINE BEETLE 



The mountain pine beetle, an indigenous organism in lodgepole vine ecosystems, 

 exerts numerous and varied effects upon lodgepole pine stands. The phloem layer of the 

 tree comprises the feeding and breeding liabitat of the beetles; they spend a large 

 portion of their life cycle in this layer. The adult beetle feeds upon and constructs 

 ^ egg gallery in the phloem. The beetle larvae feeding at right angles to the egg 

 gallery, in conjunction with blue stain fungi, girdle the tree and cause its death. 



Evenden, James C. History of the mountain pine beetle infestation in the lodgepole 

 pine stands of Montana. USDA Forest Insect Laboratory, Coeur d'Alene, Idaho, type- 

 written report, 25+ pp., illus. 1934. 



