, 4 '<P7, l-TgT . , 



Figure 3.— The Populus 

 tremuloides/Symphoricarpos 

 oreophilus/Senecio serra c.t. 

 such as this stand on the 

 Uinta National Forest near 

 the Payson Guard Station, is 

 a prominent northern Utah 

 aspen type. The 

 undergrowth generally 

 consists of a rich mixture of 

 tall and low forbs, 

 graminoids, and low shrubs 

 dominated by S. oreophilus. 



(3.3 and 53.4 m^/ha) and averaged 115 ft^/acre 

 (26.4 m^/ha). Only 2 percent of this basal area consisted 

 of conifers. Aspen site index at 80 years ranged from 26 

 to 71 ft (7.9 to 21.6 m) and averaged a moderately low 

 48 ft (14.5 m). Aspen reproduction in these mature 

 stands was about equally divided between suckers less 

 than 1 ft (0.3 m) high and those over this height. Num- 

 ber of suckers was highly variable, from almost complete 

 absence to over 20,000/acre (50 000/ha), but averaged a 

 moderate 2,700/acre (6 600/ha). 



The quantity of undergrowth is also variable but 

 generally consists of a fairly productive mixture of 

 different vegetation classes. Annual production averaged 

 1,340 lb/acre (1 504 kg/ha) and ranged from 386 to 2,654 

 lb/acre (434 to 2 956 kg/ha). An average 20 percent of 

 this consisted of shrubs, principally S. oreophilus, 55 

 percent of forbs, and 25 percent of graminoids. Almost 

 90 percent of the undergrowth was comprised of species 

 that are considered desirable (51 percent) or of intermedi- 

 ate forage suitability (37 percent). The type, therefore, is 

 fairly good summer range for both sheep and cattle. 

 Wildlife habitat values may be less than optimum 

 because of the lack of a tall shrub layer. 



Aspen communities with undergrowth of only a low 

 shrub stratum primarily of S. oreophilus and an herba- 

 ceous layer with good representation of tall forbs are 

 fairly widespread. Mueggler and Campbell (1982) 

 described a P. tremuloides/S. oreophilus-R. occidentalis 

 c.t. in southeastern Idaho that is similar to our Utah 

 type except their stands appear to be more severely 

 altered by abusive grazing. A P. tremuloides/S. oreophilus 

 c.t. was identified for western Wyoming that is also fairly 

 similar (Youngblood and Mueggler 1981). About a third of 

 the stands in the more generalized P. tremuloides/ 

 S. oreophilus habitat type described for the Routt National 

 Forest (Hoffman and Alexander 1983) and about a fourth of 

 those in the P. tremuloides/S. oreophilus habitat type 

 described for the White River National Forest (Hoffman 

 and Alexander 1980) in northwestern Colorado appear struc- 

 turally and compositionally similar to our POTR/SYOR/ 

 SESE c.t. 



Pop ulus trem uloides/Sym ph oricarpos 

 oreophilus/Carex geyeri Community 

 Type (POTR/SYOR/CAGE c.t.) 



This relatively common community type is widely dis- 

 tributed across all National Forests in Utah. Stands 

 were encountered at elevations ranging from 6,100 to 

 9,400 ft (1 860 to 2 870 m). The type occurred on all 

 exposures on mountain slopes usually less than 25 per- 

 cent in steepness. About half the stands in this type 

 grew on soils of sandstone origin, and about a fourth on 

 granitic soils. 



The indicator species Carex geyeri, Carex rossii, and 

 Stipa occidentalis are believed to reflect similar environ- 

 mental situations, yet they do not necessarily frequent 

 the same geographical areas. Carex geyeri is a primary 

 undergrowth component only on the Uinta, Ashley, and 

 Manti-LaSal National Forests; C. rossii and S. occiden- 

 talis prevail as indicator species on the Fishlake and 

 Dixie National Forests where C. geyeri is usually absent. 

 This presents a dilemma in naming community types: 

 either we unnecessarily increase the number of commu- 

 nity type names, or we select a single species to reflect 

 the undergrowth portion of the epithet even though it 

 may not be present in all areas. We have chosen the lat- 

 ter; C. geyeri is used in the epithet to represent all three 

 species of graminoids. 



The POTR/SYOR/CAGE c.t. has a considerably less 

 diverse assemblage of species than the POTR/SYOR/ 

 SESE c.t. Both types are essentially three layered, with 

 an aspen-dominated overstory, and a Symphoricarpos 

 oreophilus shrub stratum. The herbaceous undergrowth 

 in the POTR/SYOR/CAGE c.t., however, is less complex. 

 This undergrowth usually has an abundance of grami- 

 noids accompanied by low-growing forbs. As noted 

 above, we consider C. geyeri, C. rossii, and S. occidentalis 

 to more or less indicate equivalent abiotic environments, 

 even though they may react somewhat differently to dis- 

 turbance such as grazing. Frequently Agropyron 

 trachycaulum and Poa pratensis are also common grami- 

 noids. Some of the more common forbs include 



17 



