Populus tremuloidesf Juniper us communis/ 

 Sit anion hystrix Community Type 

 (POTR/JUCO/SIHY c.t.) 



Though not common, this community type was 

 encountered intermittently across most of the National 

 Forests of Utah. We sampled 21 stands within the type. 

 The type occurred most frequently in the Uinta Moun- 

 tains in northeastern Utah but extended southward to 

 the Aquarius and Markagunt Plateaus in southern Utah. 

 This is a mid-elevation type with over 80 percent of the 

 stands in the 8,000 to 9,000 ft (2 440 to 2 740 m) eleva- 

 tion zone. Most of the stands grew on soils derived 

 either from granite or sandstone. 



Vegetation in the POTR/JUCO/SIHY c.t. reflects a 

 drier environment than that occupied by the 

 POTR/JUCO/CAGE c.t. The shrub layer is typified by 

 the dominance of Juniperus communis or Artemisia 

 tridentata or both. Other shrubs frequently present in 

 noticeable amounts are Symphoricarpos oreophilus and 

 Berberis repens. The herbaceous undergrowth is com- 

 paratively poor and is typified by the substantial pres- 

 ence of one or more of the grasses Sitanion hystrix, 

 Stipa comata, and Stipa lettermanii. Forbs are generally 

 sparse. Most frequently encountered are Achillea 

 millefolium, Taraxacum officinale, and Lupinus 

 argenteus. The latter at times forms the major part of 

 the undergrowth biomass. 



This community type is primarily a relatively dry-site, 

 stable aspen type. In some situations, where Pinus 

 ponderosa or Pseudotsuga menziesii are actively invad- 

 ing the aspen stand, the type may be a serai stage 

 within the P. ponderosa/Festuca idahoensis habitat type 

 in northern Utah (Mauk and Henderson 1984), or possi- 

 bly the P. menziesii/B. repens habitat type farther south 

 (Youngblood and Mauk 1985). Abusive grazing in this 

 type could lead to an increase in the shrubs A. tridentata 

 and J. communis, the forbs A. millefolium and T. 

 officinale, and possibly in the grass Poa pratensis. 



Production was not measured in this type. It probably 

 is a less productive livestock range and wildlife habitat 

 than the POTR/JUCO/CAGE c.t. because of a drier 

 environment and lower proportion of vegetation in the 

 desirable forage suitability class. Wood production is 

 also likely below that of the POTR/JUCO/CAGE c.t. 

 Undergrowth production probably averages less than 

 535 lb/acre (600 kg/ha) and tree production less than 

 130 ft2/acre (30 m^/ha). 



Although aspen communities with a low shrub layer 

 dominated by J. communis have been reported elsewhere 

 (Youngblood and Mueggler 1981; Wirsing and Alexander 

 1975), none have herbaceous undergrowth composition 

 similar to that in our POTR/JUCO/SIHY c.t. 



Pop ulus trem uloides/Sym ph oricarpos 

 oreophilus/Bromus carinatus Community 

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



This infrequent community type was represented by 

 only 12 stands principally in northern Utah on the Bear 

 River and Wasatch Ranges. One stand was in the Abajo 

 Mountains in southeastern Utah. The type occurred at 

 elevations ranging from 6,400 to 8,600 ft (1 950 to 

 2 620 m), on all exposures, but primarily on sandstone 

 and quartzite derived soils. 



Vegetation of the POTR/SYOR/BRCA c.t. reflects 

 appreciable alteration because of livestock grazing. The 

 vegetation consists essentially of three strata: trees, low 

 shrubs, and herbs. The tree layer is virtually pure aspen; 

 conifers are present occasionally but only in minor 

 amounts. The shrub layer may be a mixture of various 

 species, but Symphoricarpos oreophilus is the only one 

 that has both high constancy and abundance. 

 Amelanchier alni folia and other tall shrubs sometimes 

 may be present but never in sufficient abundance to 

 form a definite stratum of tall shrubs. The herbaceous 

 undergrowth is characterized by the abundance of the 

 tall grasses Bromus carinatus or Elymus glaucus or 

 both; Agropyron trachycaulum is usually present in sub- 

 stantial quantities. Although a variety of forbs may be 

 present in any one stand, constancy between stands of 

 any single species is generally low. Geranium 

 viscosissimum and Lathyrus spp. appear to be the most 

 representative forbs. 



We believe that this type is primarily a serai stage 

 leading to a climax aspen POTR/SYOR/SESE c.t. The 

 paucity of tall forbs that commonly exist in the 

 POTR/SYOR/SESE c.t. and the proportionately greater 

 role of B. carinatus and E. glaucus in the undergrowth 

 are attributed to grazing influences, probably by 

 sheep. Heavy, continued grazing pressure could lead to 

 yet more pronounced changes, such as a decrease in 

 S. oreophilus, a replacement of desirable perennial herbs 

 with yet greater amounts of Poa pratensis. Taraxacum 

 officinale, and possibly Lathyrus spp. Where conifers 

 appear able to actively invade, such stands may be a 

 serai stage in the Abies lasiocarpa/Osmorhiza chilensis 

 habitat type (Mauk and Henderson 1984). 



Only two stands were sampled for productivity. Based 

 on this small sample, wood production appears to be 

 fairly low. Basal area of trees was a low 97 and 

 109 ft^/acre (22.3 and 25.1 m^/ha); 94 percent of this was 

 aspen and the remainder was conifers. Aspen site index 

 at 80 years was a moderate 48 and 62 ft (14.6 and 

 18.9 m). Aspen reproduction was moderate at approxi- 

 mately 2,600 suckers/acre (6 500/ha), almost 40 percent 

 of which were 1 to 4.6 ft (0.3 to 1.4 m) high. 



Undergrowth production was low to moderate. Total 

 production within the two stands was 463 and 1,583 

 lb/acre (519 and 1 777 kg/ha). This was distributed 

 among vegetation classes as follows: 12 percent shrubs, 

 29 percent forbs, and 59 percent graminoids. Of the total 

 undergrowth, 97 percent was in the desirable and inter- 

 mediate forage suitability groups. This serai type 

 produces less forage of a considerably different character 

 than the successionally related POTR/SYOR/SESE c.t., 



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