Populus tremuloides-Pinus contort a/ 

 Juniperus communis Community Type 

 (POTR-PICO/JUCO c.t.) 



The POTR-PICO/JUCO c.t. is a local serai type 

 encountered only in the Uinta Mountains of northern 

 Utah, where it is fairly common. It occurs on both the 

 north and south flanks of this range at elevations 

 usually above 8,000 ft (2 440 m). The 29 stands sampled 

 in this type were not restricted by either slope or 

 exposure but were confined primarily to soils derived 

 from either sandstone or quartzite parent materials. 



This is the more common of the two community types 

 in which Pinus contorta is strongly associated with 

 Populus tremuloides in the tree overstory. The under- 

 growth is composed of a low shrub layer dominated by 

 Juniperus communis and an herb layer in which various 

 graminoids are usually prominent. Berberis repens and 

 Rosa woodsii are the shrubs most commonly associated 

 with J. communis, but occasionally Arctostaphylos uva- 

 ursi or Symphoricarpos oreophilus may occur in some 

 abundance. Carex ^eyeri, Stipa occidentalism Agropyron 

 trachycaulum, and Bromus ciliatus are usually the most 

 prominent graminoids. The forb component consists of a 

 mixture of species. The most common are Achillea 

 millefolium, Astragalus miser, Lupinus argenteus, 

 Geranium viscosissimum, Thalictrum fendleri, 

 Antennaria microphylla, Fragaria vesca, and Potentilla 

 gracilis. 



The serai status of the POTR-PICO/JUCO c.t. is 

 apparent from the abundance of P. contorta in the tree 

 overstory. Succession is obviously away from dominance 

 by P. tremuloides and toward dominance by the more 

 shade-tolerant conifer. Undergrowth similarities suggest 

 that succession may be toward the P. contorta/B. repens 

 or possibly the P. contortaJJ. communis community 



types. Mauk and Henderson (1984) indicate that the 

 P. contorta/B. repens type is climax in some situations. 

 In others, particularly where C. geyeri is abundant and 

 Abies lasiocarpa is present, it is a serai type within the 

 A. lasiocarpa/B. repens habitat type. Mauk and 

 Henderson consider the P. contortaJJ . communis commu- 

 nity type to be primarily a serai stage within the 

 A. lasiocarpa/J. communis habitat type. Thus, the POTR- 

 PICO/JUCO type may represent a serai stage within at 

 least three habitat types: P. contorta/B. repens, A. 

 lasiocarpa/B. repens, and A. lasiocarpa/J. communis. 



Tree production within this type is low to moderate. 

 Basal area ranged from 104 to 178 ft^/acre (23.8 to 

 40.8 m2/ha) and averaged 135 ft^/acre (31.0 m^/ha). Of 

 this basal area, 16 percent was conifers, primarily 

 P. contorta. Aspen site index at 80 years ranged from 37 

 to 51 ft (11.3 to 15.5 m) and averaged a low 42 ft 

 (12.9 m). Aspen reproduction averaged a low 676 

 suckers/acre (1 670/ha), but 70 percent of these were in 

 the 1- to 4.6-ft (0.3- to 1.4-m) size class. Conifer regenera- 

 tion averaged 236 seedUngs/acre (584/ha), of which 30 

 percent were in the larger size class. Approximately half 

 of these seedlings were P. contorta, the other half Abies 

 lasiocarpa. 



Undergrowth production is low, ranging from 290 to 

 824 lb/acre (326 to 925 kg/ha) and averaging only 

 603 lb/acre (677 kg/ha). Of this, 8 percent was shrubs, 

 primarily J. communis, 71 percent forbs, and 21 percent 

 graminoids. The undergrowth is moderately desirable as 

 forage with 44 percent in the desirable class and 51 per- 

 cent in the intermediate class. But this type is rather 

 poor range for Uvestock because of low forage produc- 

 tion. It has only moderate value as wildlife habitat. 



This serai type is not known to occur outside of the 

 Uinta Mountains in northeastern Utah. 



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