THE AUTHORS 



RUSSELL T. GRAHAM is a research forester in the 

 research work unit on silviculture of cedar, hennlock, 

 grand fir, and Douglas-fir ecosystems and tree dis- 

 eases of the Northern Rocky Mountains. The unit is at 

 the Intermountain Research Station's Forestry 

 Sciences Laboratory, Moscow, ID. He began his career 

 with the Forest Service in 1973 as a forester on the 

 Bitterroot National Forest and joined the Intermoun- 

 tain Station in 1975. He received his B.S. degree in for- 

 estry from the University of Montana and his M.S. and 

 Ph.D. degrees in forestry from the University of Idaho. 



JONALEA R. TONN is a forester working in the 

 research work unit on silviculture of cedar, hemlock, 

 grand fir, and Douglas-fir ecosystems and tree dis- 

 eases of the Northern Rocky Mountains. She began 

 working for the Intermountain Research Station in 

 1974. She received B.S. and M.S. degrees, both in for- 

 estry, from the University of Idaho. 



ACKNOWLEDGMENT 



As in any long-term study, many individuals have 

 contributed to its successful completion. The most 

 prominent include Glenn Deitschman who started the 

 study, Ray Boyd, and the late Marvin Foiles, all 

 research silviculturists who provided continuity and 

 valuable assistance. 



RESEARCH SUMMARY 



Forest fertilization is a successful cultural treatment 

 for increasing forest yields. However, research has 

 shown wide variability in response of forest stands to 

 the application of fertilizer. Results of most studies on 

 nitrogen fertilizer, the most commonly applied nutrient, 

 are highly dependent on site and species. 



This study also shows high variability that can be 

 expected from the application of fertilizer. Ten years 

 after the application of nitrogen fertilizer in the form 

 of urea at 200 and 400 lb per acre, only short-term 

 differences in tree growth could be detected between 

 fertilized and unfertilized trees. No major differences 

 were evident after 10 years. Grand fir {Abies grandis 

 [Dougl. ex D. Don] Lindl.) had the best response to fer- 

 tilizer 5 years after application with a 45 percent 

 increase in diameter growth at that time. Fertilized 

 western white pine (Pinus monticola Dougl.) were 

 growing slower than the unfertilized pine after either 5 

 or 10 years. How tree species respond to the applica- 

 tion of fertilizer may be related to their successional 

 position in a stand and their tolerance to different 

 ranges or levels of nitrogen nutrition. 



