THE AUTHORS 



RESEARCH SUMMARY 



CLINTON E. CARLSON is research forester with the 

 Forestry Sciences Laboratory in Missoula, MT. He 

 earned his B.S. in forest science in 1964, M.S. in 

 forestry in 1966, and Ph.D. in botany in 1978 from the 

 University of Montana. From 1966 until 1979 he was 

 plant pathologist with the Northern Region, USDA 

 Forest Service, where he conducted field and labora- 

 tory studies on the effects of air pollutants on forest 

 ecosystems. Since 1979 he has conducted research 

 concerning the interrelationships between silvicultural 

 practices and western spruce budworm for the Inter- 

 mountain Research Station in Missoula. 



ROBERT D. PFISTER is director of the Mission 

 Oriented Research Program, Montana Forest and 

 Conservation Experiment Station, at the University of 

 Montana. His work involves research on basic ecologi- 

 cal resources of forests and the integration of 

 research information into management planning. Prior 

 to his current assignment, he was principal plant eco- 

 logist with the Intermountain Forest and Range Experi- 

 ment Station. USDA Forest Service, in Missoula. MT, 

 where he was project leader of the forest ecosystems 

 research work unit. He holds B.S. and M.S. degrees in 

 forest management from Iowa State University and 

 Oregon State University, respectively, and a Ph.D. in 

 botany from Washington State University. 



LEON J. THEROUX is biological technician with the 

 Forestry Sciences Laboratory in Missoula, MT. He 

 earned a B.S. in forestry in 1971 from the University of 

 Montana. Since 1978 he has been involved in research 

 concerning the effects of western spruce budworm on 

 forests of the Northern Rocky Mountains and studies 

 concerning factors influencing seed and cone develop- 

 ment in western larch forests. Prior to his current 

 assignment, he was involved in forest insect research 

 at the Forestry Sciences Laboratory in Moscow, ID. 



CARL E. FIEDLER is research forester with the 

 Montana Forest and Conservation Experiment Station 

 at the University of Montana, Missoula. His research 

 activities include studies on regeneration and stand 

 management in coniferous forests of the Central and 

 Northern Rocky Mountains. Much of his work centers 

 on the Lubrecht Experimental Forest near Missoula. 



Current and past defoliation by western spruce bud- 

 worm (Choristoneura occidentalis Freeman) in an 

 80-year-old predominantly Douglas-fir (Pseudotsuga 

 menziesii var. glauca [Beissn.] Franco) stand thinned 

 to 14 by 14 feet was significantly lower than in a 

 nearby untreated stand of similar age, species, and 

 site conditions. Analysis of periodic radial growth 

 ratios indicated that prior to thinning, Douglas-fir had 

 been heavily defoliated by budworm and growth was 

 seriously depressed. Following thinning, the host leave 

 trees developed dense crowns and 10-year radial 

 growth increased an average of 57 percent; meanwhile, 

 radial growth of nonhost ponderosa pine (Pinus 

 ponderosa Dougl.) increased 38 percent. Several 

 hypotheses individually or collectively may explain this 

 effect of thinning on budworm defoliation. The thin- 

 ning may have caused increased mortality of budworm 

 larval stages, the trees simply released and outgrew 

 the insect, or the defensive chemistry of leave trees 

 was enhanced. Radial growth of ponderosa pine 

 accelerated in both the thinned and unthinned stands 

 prior to thinning. This prethinning release of pine prob- 

 ably was in response to the defoliation, and reduced 

 competition, of Douglas-fir. 



ACKNOWLEDGMENTS 



This research was done jointly between the Inter- 

 mountain Research Station and the University of 

 Montana Mission Oriented Research Program through 

 Cooperative Agreement Supplement No. 22-C-3-INT-130. 



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 the reader. Such use does not constitute an official 

 endorsement or approval by the U.S. Department of 

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