The undergrowth generally is no more than moderately 

 productive. It ranged from 437 to 1,079 lb/acre (491 to 

 1 210 kg/ha) and averaged a low to moderate 777 lb/acre 

 (872 kg/ha). An average 26 percent of this was shrubs, 

 58 percent was forbs, and 16 percent w^s graminoids. A 

 relatively high proportion of this vegetation, 55 percent, 

 was desirable forage. Less than 10 percent fell into the 

 least desirable category. This serai type, therefore, is 

 moderately productive livestock range in the earlier 

 stages of succession to conifer dominance. It is only 

 moderately desirable wildlife habitat because of the 

 somewhat limited amount of vegetation diversity. 



Although this serai community type has not been spe- 

 cifically named as occurring elsewhere, it probably can 

 be found in adjacent States. The type is considered a 

 serai stage in the development of climax A. lasiocarpa/ 

 B. repens and A. lasiocarpa/C. geyeri climax forests of 

 Utah that also occur in Idaho, Wyoming, and Colorado. 

 Steele and others (1983) list P. tremuloides as a major 

 serai tree in the A. lasiocarpa/B. repens habitat type of 

 eastern Idaho and western Wyoming. Hoffman and 

 Alexander (1980, 1983) indicate that P. tremuloides is a 

 major serai tree in the A. lasiocarpa/C. geyeri habitat 

 type of northwestern Colorado. 



Populus tremuloides-Ahies lasiocarpa/ 

 Juniperus communis Community 

 Type (POTR-ABLA/JUCO c.t.) 



The POTR-ABLA/JUCO c.t. appears restricted in 

 northern Utah to the Uinta Mountains but is much more 

 widespread farther south where it was encountered on 

 the Fishlake, Paunsagunt, and Markagunt Plateaus and 

 in the Tushar Mountains. We sampled 34 stands in this 

 type that generally occurred in the higher mountains at 

 elevations exceeding 8,000 ft (2 440 m). The type other- 

 wise does not appear restricted by either slope exposure 

 or soil parent material. 



The vegetation of this type is characterized by the 

 presence of Abies lasiocarpa or Picea engelmannii along 

 with Populus tremuloides in the overstory or as under- 

 story reproduction, the absence of a distinct tall shrub 

 layer, and a low shrub layer dominated by Juniperus 

 communis. Other conifers frequently present in lesser 

 amounts include Pseudotsuga menziesii and Pinus flexilis. 

 No single species characterizes the herbaceous under- 

 growth, which is generally a mixture of various grami- 

 noids and forbs. The most common graminoids found 

 here are Carex rossii, Stipa occidentalis, Bromus anomalus, 

 Bromus ciliatus, and Agropyron trachycaulum. Com- 

 monly encountered forbs include Achillea millefolium, 

 Fragaria vesca, Astragalus miser, and Thalictrum 

 fendleri. 



The type obviously represents a serai stage within the 

 A. lasiocarpa forest series, probably in either the 

 A. lasiocarpa/J. communis or A. lasiocarpa/Berberis 

 repens habitat types (Mauk and Henderson 1984; 

 Youngblood and Mauk 1985), judging from species 

 similarities with these habitat types. As with other such 

 aspen communities that are serai to coniferous forests, 

 dominance by P. tremuloides can only be maintained by 

 such extreme disturbance as burning, clearcutting, or 



selective removal of the conifers that would set back the 

 successional processes. Heavy livestock grazing within 

 this type would tend to change the herbaceous composi- 

 tion to favor A. miser, F. vesca, Taraxacum officinale, 

 and Poa pratensis. The abundance of shrubby J. com- 

 munis undergrowth would likely increase as well. 



Tree productivity within this type is at least moder- 

 ately good. Basal area on the 12 stands sampled for 

 productivity ranged from 98 to 263 ft-/acre (22.5 to 

 60.4 m^/ha) and averaged 166 ft^/acre (38.1 m'/ha). Only 

 10 percent of this was conifers and the rest was aspen. 

 Site index for aspen at 80 years ranged from 32 to 71 ft 

 (9.8 to 21.6 m) and averaged a moderate 52 ft (15.7 m). 

 Aspen reproduction averaged a low 730 suckers/acre 

 (1 800/ha), two-thirds of which were in the 1- to 4.6-ft 

 (0.3- to 1.4-m) size class. Conifer reproduction averaged 

 slightly less than 325 stems/acre (800/ha), of which three- 

 fourths were A. lasiocarpa, and a third of which were in 

 the large reproduction size class. 



Undergrowth production appears to be generally low, 

 ranging between 78 and 1,139 lb/acre (88 and 

 1 278 kg/ha) and averaging a low 374 lb/acre (420 kg/ha). 

 This was about equally distributed among shrubs, forbs, 

 and graminoids. The undergrowth is considered moder- 

 ately suitable for livestock with 45 percent of the vege- 

 tation in the desirable category. However, generally low 

 production limits the value of this type as hvestock 

 range. The type is also of only moderate value as wildlife 

 habitat because neither vegetation structure nor plant 

 species diversity are great. 



No one has reported this serai community type to 

 occur outside of Utah. 



Populus tremuIoides-Abies lasiocarpa/ 

 Senecio serra Community Type 

 (POTR-ABLA/SESE c.t.) 



This is one of the more common serai community 

 types found throughout the higher mountains of Utah. 

 It is most frequently encountered in northern Utah 

 along the Bear River and Wasatch Ranges and along the 

 west slope of the Uinta Mountains. Of all sampled 

 stands, 8 percent occurred in this community type. 

 Although the type was encountered at elevations as low 

 as 6,400 ft (1 950 m), over two-thirds of the stands were 

 found at elevations between 8,000 and 10,000 ft (2 440 

 and 3 050 m). The type occupied a wide variety of 

 slopes, exposures, and soils derived from different parent 

 materials. 



Vegetation of the POTR-ABLA/SESE c.t. is similar to 

 that of the POTR/SESE type, except for the prominence 

 of conifers in the former. Both types are structurally 

 simple with only a tree overstory and a predominantly 

 herbaceous undergrowth. Shrubs, especially 

 Symphoricarpos oreophilus, may occasionally be present 

 but never in sufficient abundance to form a distinct 

 layer. In addition to the paucity of shrubs, the under- 

 growth is characterized by the conspicuous presence of 

 one or more members of the tail forb complex, usually 

 either Rudbeckia occidentalis, Senecio serra. Aster 

 engelmannii, Mertensia arizonica, or Valeriana 

 occidentalis. Tall grasses that are in abundance are 



33 



