fin 

 7 



UNITED STATES DEPARTMENT OF ACRICULTUkt- 

 FOREST SERVICE 



mmmmm mm & RAfia EXPERmm srAJiof^ 



OCDEN UTAH 



No . 34 August 1956 



BOARD-FOOT INCREMENT ON RESIDUAL 

 PONDEROSA PINE IN MONTAIjA 



By 



Kenneth N. Boe and David Tackle 

 Division of Forest Management Research 



In the partial cutting of forest stands, growth of the residual ^, 

 trees is an important management consideration. A cooperative study- 

 established in 1932 in the Blackfoot Valley in western Montana relates 

 growth to three different levels of reserve in mature ponderosa pine. 

 The stands originally contained from 15,000 to 20,000 board feet per 

 acre on Site Index 70. Twenty-year records disclose that 4,000 to 

 8,000 board feet per acre of vigorous, well-spaced trees, between 120 

 and 220 years old and of moderate size comprised a satisfactory reserve. 



METHODS 



A virgin ponderosa pine stand on Site Index 70 (age 100) was 

 chosen for study. Three contiguous plots of 4 to 7 acres each were 

 given different cutting treatments. The cuttings were called locally, 

 according to prevailing practice in 1932, a "clear cutting," an 

 "intensive-silvicultural selection cutting," and an "economic" or 

 "zero-margin cutting. "2/ The stated objectives were to compare 



1/ Gooperators were the Montana State Department of Forestry; 

 School of Forestry, Montana State University; Lumber Department, The 

 Anaconda Company; Northern Region, U. S. Forest Service; and the North- 

 ern Rocky Mountain Forest and Experiment Station which was consolidated 

 in 1953 with the Intermountain Forest and Range Experiment Station. 



2_/ Anderson, I. V. Application of selective logging to a ponderosa 

 pine operation in western Montana, State University of Montana Studies 

 2, 56 pp. Missoula. 1934. 



