THE AUTHORS 



RESEARCH SUMMARY 



CLINTON E. CARLSON is a research forester at the Inter- 

 mountain Research Station, Forestry Sciences Laboratory, 

 Missoula, MT. He has conducted extensive work on the 

 effects of air pollution on forest ecosystems. He currently is 

 researching interactions between western spruce budworm 

 and forests in the Northern Rocky Mountains and hybridiza- 

 tion between western and alpine larch. He holds B.S. and 

 M.S. degrees in forestry and a Ph.D. in botany from the 

 University of Montana. 



WYMAN C. SCHMIDT is a research silviculturist and Project 

 Leader of the Silviculture of Conifers in Montane and Sub- 

 alpine Ecosystems of the Intermountain and Northern Rocky 

 Mountain West research work unit at the Forestry Sciences 

 Laboratory, Bozeman, MT. Dr. Schmidt's research has 

 focused on the ecology, regeneration processes, stand de- 

 velopment, and related cultural practices in coniferous 

 forests of the Intermountain West. Much of his research has 

 centered on the interrelationships of timber, water, and other 

 resources as well as the interaction of cultural practices with 

 insect pests such as western spruce budworm. 



The influence of four levels of overstory removal on height 

 and diameter growth of advance regeneration was assessed 

 in larch/Douglas-fir stands in subalpine fir habitat types of 

 northwestern Montana. This study was part of a much larger 

 effort focused on utilization of trees at Coram Experimental 

 Forest. Twelve-year diameter growth of Douglas-fir and 

 Engelmann spruce accelerated with increasing overstory 

 removal, whereas subalpine fir diameter growth increased as 

 the amount of basal area removed increased. Eleven-year 

 height growth of Douglas-fir increased with increasing 

 change in basal area; height growth of subalpine fir in- 

 creased with both change in basal area and degree of over- 

 story removal. Height growth of spruce increased only with 

 increasing prerelease 10-year radial growth. For Douglas-fir 

 and subalpine fir, height and diameter growth responded to 

 some measure of reduced competition. Nevertheless, radial 

 growth prior to treatment was the variable most indicative of 

 both height and diameter growth of all species. Trees grow- 

 ing well before treatment also grew well following treatment. 

 Mortality was lowest where either all or none of the overstory 

 was removed and was greatest where about 50 percent of 

 the overstory was removed. Western spruce budworm, 

 present in damaging numbers during study establishment, 

 declined soon after harvest and was not present during 

 remeasurement. Defoliation at time of study establishment 

 was greatest on taller trees of all species but significantly 

 affected height growth only of Douglas-fir. Because of the 

 mediocre growth response and the increased susceptibility 

 of such stands to budworm, future volumes in stands com- 

 posed of and managed for shade-tolerant species may be 

 substantially below volumes expected from stands com- 

 posed of serai species in these high-quality habitats. 



Intermountain Research Station 

 324 25th Street 

 Ogden, UT 84401 



