class rating was also assigned (Daubenmire 1959) . A size-age-form class rating was 

 assigned each individual tree on the macroplot (Blackburn and Tueller 1970) . Further 

 details of the "rapid" methodology, including collection of topographic and edaphic 

 data, can be found elsewhere (Beeson 1974). 



In the "detailed" level of sampling, the same plot size and methodology were 

 used, but data were obtained from direct measurements using an expansion and intensifi- 

 cation of the previously described methodology. The 66 by 165 foot (20 by 50 m) macro- 

 plots were permanently marked. Four trees of each size-age-form class of each species 

 situated closest to two predetermined points were measured. Crown spread of these 

 trees in the widest and narrowest dimensions was recorded. Tree cover for the plot was 

 estimated by taking an average of tree crown dimensions, computing elliptical area on 

 the measured trees, and multiplying by the number of trees of each size-age-form class. 

 Shrub crown cover was estimated to the nearest 2 percent (Daubenmire 1959) in randomly 

 stratified 1 by 2 m microplots. Forb and grass basal cover was similarly estimated in 

 3 by 6 m plots located within the shrub sampling scheme. The "detailed" sampling 

 approach is described more fully in Nabi (1978) . 



All mountain ranges sampled were selected by the same process. The 18 ranges 

 sampled with "detailed" methodology were randomly selected from the larger set (table 1) . 

 The remainder were sampled with "rapid" techniques. The procedure for plot location 

 was identical on all mountain ranges regardless of which sampling strategy was used. 

 Plots were thoroughly searched for all plant species present under both "rapid" and 

 "detailed" sampling strategies. 



Taxonomic vouchers of plants were collected at each site with special attention 

 given to sagebrush {Artemisia spp.). Specimens were checked for proper identification 

 against vouchers at the Intermountain Herbarium, Utah State University. Artemisia 

 specimens were segregated morphologically following the works of Brunner (1973) and 

 Winward and Tisdale (1977) . However, the more effective process of chromatographic 

 differentiation was used to determine subspecies of A. tridentata as well as to confirm 

 placement in other Artemisia taxa. The chromatographic procedures used were similar to 

 those described by Hanks and others (1973) . Vouchers specimens of all taxa are on file 

 at Utah State University. 



vegetation Type Mapping 



Pinyon- juniper woodlands were mapped during the winter of 1973-74, using LANDSAT-1 

 color-infrared composites (fig 2) . Woodland boundaries for the entire study area were 

 mapped to an approximate scale of 1:1,000,000 where 1 inch (2.5 cm) equals approxi- 

 mately 16 miles (26 km) on the ground. Areas of pinyon- juniper woodland as small as 

 62 acres (25 ha) were mapped. The pinyon- juniper vegetation type was identified by a 

 reddish-orange color on the composites. 



The low-elevation boundary of the woodland was easily mapped from summer color 

 composites, but the upper boundary diffused into other, more infrared reflective 

 vegetation types, making the pinyon- juniper difficult to map from photos taken during 

 the growing season. The upper boundary was mapped using winter images taken when 

 pinyon- juniper woodlands were the only infrared reflective vegetation type. All 

 other types of vegetation were either dormant or covered with snow (Tueller and others 

 1975) . 



The extent of the pinyon- juniper woodland type in the Great Basin was determined 

 from the completed map using a 256 dot/in^ (150 dots/cm^) grid. The total number of 

 dots counted in the woodland was multiplied by an appropriate conversion factor to 

 obtain acres or hectares per dot. 



6 



