relative abundance of the same species in other types. Those 

 data were used to calculate estimates of total forage produced 

 on the study area during summer and autumn. The estimates 

 were developed with very conservative parameters that included 

 the following: 



1) Distribution cells in which deer were not observed during 

 aerial surveys (17% of area) were not included in forage 

 calculations although they undoubtedly received at least 

 minor use by deer. 



2) Minor vegetation-cover types in which relative forage 

 abundance was not measured (an additional 9% of area) 

 were either assigned no value for forage, or a level 

 equivalent to the value in the lowest type measured. 

 Several of these types (river riparian, pine- juniper- 

 Douglas fir, and grassy bottoms) were probably above 

 average in forage production. 



3) Only those forbs known to be preferred by deer during 

 summer and, autumn were used to calculate forb production. 



4) The production of 2 very important shrubs (rubber 

 rabbitbrush and green rabbitbrush) was not estimated or 

 included, although they often averaged up to one-third of 

 the autumn diet. 



5) Only one-half of the forage in the big sagebrush habitat 

 in which deer were observed was considered usable. 



6) After the previous 5 factors had been included in 

 calculations, only one-half of the estimated forage yield 

 was considered usable by deer. 



7) Regrowth of forage plants was not considered. 



An example of the data and calculations involved in these 

 estimates is presented in Appendix B. The results (Table 

 3.8), together with data presented in Figure 3.9 indicated 

 that the quantity of forage during summer and autumn was 

 adequate to support existing deer populations throughout the 

 period 1959-1986. Only in 1985, did the available quantity of 

 forage during summer and autumn appear to approach a shortage. 

 However, even then, given the conservative assumptions of the 

 calculations and the fact that an autumn "green-up" of grasses 

 and forbs occurred in 1985, it is unlikely that the quantity 

 of forage was insufficient. Similar conclusions about the 

 quantity of summer-autumn forage were made for a Colorado mule 

 deer range (Wallmo et al . 1977). 



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