DISCUSSION 



Shrub Respcmse 



The response o£ overmature bitterbrush shrubs to topping on the three widely 

 separated sites substantiated the previous findings of the 1960 tests near Boise. 

 Environmental conditions in a particular year will affect overall shrub response on 

 each site. Variation in the vigor of individual old shrubs will result in obvious 

 differences in total amount of twig growth produced following topping. 



Some twigs produced on tall, overmature bitterbrush shrubs are above the reach of 

 deer. Thus, the calculated amounts of available forage shown for an untopped stand 

 in table 3 are somewhat liberal. On the other hand, for several years following top- 

 ping, virtually all twig production is available to deer. Of the three study areas 

 involved, the Boise site probably had the highest proportion of tall shrubs. Shrubs 

 on the Sawtooth site were generally smaller than those on either the Boise or the 

 Modoc site. 



If the sample shrubs were representative of the productivity of most shrubs on the 

 three study areas, the Modoc site was by far the most productive (table 3). A bitter- 

 brush stand such as that on the Modoc may not appear to need treatment to increase 

 available forage. However, the Modoc results indicate the large increase in browse 

 production possible from shrubs growing on a favorable site. At the other extreme, a 

 stand similar to that on the Sawtooth site may be producing relatively small amounts 

 of browse; so the increase in production that follows topping becomes important to 

 wintering deer. Any decision as to whether or not topping is a justifiable practice 

 will depend on how badly additional forage is needed on a particular portion of winter 

 range. Certainly, more winter forage will be obtained per dollar invested on an area 

 that has a high density of old shrubs than on an area that has only a scattering of 

 old shrubs. 



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