INTRODUCTIOIV 



Bitterbrush, Purshia tridentata (Pursh) DC, a deciduous shrub native to much of 

 the Intermountain West, generally is an important component of the winter diet of deer. 

 From 1959 to 1963, an exploratory study was conducted near Boise, Idaho, to determine 

 the effect of topping on subsequent annual twig production of overmature bitterbrush 

 shrubs (Ferguson and Basile 1966). Removal of a considerable portion of the shrub 

 canopy resulted in a substantial increase in annual twig production. 



As a followup to this initial effort, a more comprehensive study was planned to 

 evaluate shrub response under a wider variety of environmental conditions. Also, methods 

 of topping and the economic feasibility of large-scale topping projects were assessed. 



In the spring of 1966, the Boise, Modoc, and Sawtooth National Forests participated 

 with the Intermountain Forest and Range Experiment Station in a field test of the top- 

 ping technique. This paper reports on both shrub response and factors affecting the 

 cost of topping. Some observations on shrub longevity and the effect of repetitive 

 topping are also presented. 



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