The Authors 



Research Summary 



Lynn A. Rasmussen is Supervisory Technician, 

 Mountain Pine Beetle Population Dynamics Research 

 Work Unit, Intermountain Research Station, located 

 at the Forestry Sciences Laboratory, Logan, UT. 



Gene D. Amman (retired) was Principal entomologist 

 and Project Leader, Mountain Pine Beetle Population 

 Dynamics Research Work Unit, Intermountain Research 

 Station, located at the Forestry Sciences Laboratory, 

 Ogden, UT. 



James C. Vandygriff in Biological Technician, Mountain 

 Pine Beetle Population Dynamics Research Work Unit, 

 Intermountain Research Station, located at Forestry 

 Sciences Laboratory, Logan, UT. 



Robert D. Oakes is Biological Technician, Forest Pest 

 Management, Northern Region, Coeur d'Alene Field 

 Office, Coeur d'Alene ID. 



A. Steven Munson is Supervisory Entomologist, Forest 

 Pest Management, Intermountain Region, Ogden Field 

 Office, Ogden, UT. 



Kenneth E. Gibson is Entomologist, Forest Pest Man- 

 agement, Northern Region, Missoula, MT. 



Extensive surveys of bark beetle and wood borer infes- 

 tation in the Greater Yellowstone Area were conducted 

 in 1991 through 1993. The study objectives were to 

 determine the effect of delayed tree mortality following 

 the 1988 fires on mosaics of fire-killed and green tree 

 stands, the relationship between fire injury and subse- 

 quent infestation, and the effect of insect buildup in fire- 

 injured trees on infestation rates for uninjured trees. 

 Surveys were conducted adjacent to roads, and plots 

 were selected randomly. In 1991, 321 plots were meas- 

 ured, 198 plots in 1992, and 127 plots in 1993. Insects 

 killed 12.6 percent of the Douglas-fir (Pseudotsuga 

 menziesii), 17.9 percent of the lodgepole pine (Pinus 

 contorta), 6.6 percent of the Engelmann spruce (Picea 

 engelmannii), 7.5 percent of the subalpine fir {Abies 

 lasiocarpa), and 2.8 percent of the whitebark pine (Pinus 

 albicaulis). Delayed mortality attributed to fire injury ac- 

 counted for more mortality than insects. Both types of 

 mortality greatly altered the original fire-killed/green tree 

 mosaics that were apparent immediately after the 1988 

 fires. Insect infestation was strongly and positively cor- 

 related with the percent of the basal circumference of the 

 tree that was fire killed in all species, except in Engel- 

 mann spruce where infestation peaked in the middle 

 fire-injury class. Infestation in Douglas-fir, lodgepole 

 pine, and Engelmann spruce increased through 1992 

 then declined in 1993. Although it cannot be said with 

 certainty that insects built up in fire-injured trees and 

 then caused increased infestation of uninjured trees, 

 the high level of infestation suggests this is the case. 



Intermountain Research Station 

 324 25th Street 

 Ogden, UT 84401 



