consisted of forbs and a third was graminoids. About 

 half the undergrowth was considered to be in the desira- 

 ble Uvestock forage category. The undergrowth provides 

 poor Uvestock range primarily because of generally low 

 productivity. Wildlife habitat values are usually low 

 because the vegetation lacks diversity in both species 

 composition and community structure. 



This serai type has not been specifically identified as 

 occurring outside of Utah. However, similar serai com- 

 munities probably can be found at least in northwestern 

 Colorado. Hoffman and Alexander (1980, 1983) identified 

 an A. lasiocarpaJC. geyeri habitat type on the Routt and 

 White River National Forests that has P. tremuloides as 

 a major serai tree. 



Populus tremuloides-Abies concolor/ 

 Symphoricarpos oreophilus Community 

 Type (POTR-ABCO/SYOR c.t.) 



The POTR-ABCO/SYOR c.t., an intermediate eleva- 

 tion type, is widely scattered through central and south- 

 ern Utah. It was most frequently encountered on the 

 Wasatch Plateau and in the San Pitch Mountains. The 

 27 stands sampled in this type occurred at elevations 

 ranging from 7,200 to 8,900 ft (2 190 to 2 710 m) and 

 primarily on soils derived from sedimentary parent 

 materials, usually sandstone. 



This is one of two aspen-dominated types recognized 

 as successional to an Abies concolor climax forest. Being 

 the more moist of the two types, the undergrowth is 

 characterized by an abundance of Symphoricarpos 

 oreophilus in a distinct low shrub stratum and the con- 

 spicuous presence of members of the tall forb and tall 

 grass groups in the herbaceous layer. The tree overstory 

 contains substantial quantities of A. concolor, or occa- 

 sionally Picea pungens. Frequently Berberis repens and 

 Rosa woodsii are conspicuous shrub associates. No sin- 

 gle species characterizes the herbaceous stratum. 

 Instead, various combinations of Aster engelmannii, 

 Rudbeckia occidentalis, Agastache urtici folia, Mertensia 

 arizonica, Senecio serra, Bromus carinatus, Elymus 

 glaucus, and Agropyron trachycaulum predominate. In 

 addition, Lathyrus spp., Osmorhiza chilensis, and 

 Thalictrum fendleri are frequent associates. 



Given time and freedom from disturbance, stands 

 within this community type will eventually succeed to 

 A. concolor dominance. Undergrowth species' similarities 

 suggest that the type most likely is a serai stage within 

 A. concolor/B. repens or possibly A. concolor/ O. chilensis 

 habitat types (Mauk and Henderson 1984; Youngblood 

 and Mauk 1985). As A. concolor or P. pungens densities 

 increase, and Populus tremuloides cover diminish, under- 

 growth production of tall herbs will give way to the 

 more shade-tolerant O. chilensis, T. fendleri, and B. 

 repens. 



Under heavy cattle grazing, an increase in 

 R. occidentalis and possibly Lathyrus spp. can be 

 expected at the expense of the more palatable tall forbs 

 and grasses. Heavy sheep use is likely to suppress 

 S. oreophilus as weU as the palatable tall forbs. 

 Prolonged abusive grazing could lead to substantial 



increases in the abundance of the grazing-tolerant 

 Taraxacum officinale and Poa pratensis. 



The type apparently is able to support substantial tree 

 basal area but at a rather low rate of growth. Stands 

 sampled for productivity ranged in basal area from 106 

 to 215 ft^/acre (24.2 to 49.3 m^/ha) and averaged a high 

 177 ft^/acre (40.7 m^/ha). Conifers were 30 percent of 

 this. Aspen site index at 80 years was generally low, 

 ranging from 29 to 63 ft (8.8 to 19.2 m) and averaging 

 only 42 ft (12.8 m). Aspen reproduction in these stands 

 was also low. Less than 330 suckers/acre (800/ha) were 

 produced on the average, of which about half were in the 

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

 averaged almost 650 stems/acre (1 600/ha), with 8 per- 

 cent in the large size class. Over three-fourths of the 

 conifer regeneration consisted of A. concolor seedlings. 



Undergrowth production is generally low. Annual 

 production ranged between 188 and 1,036 lb/acre (211 

 and 1 162 kg/ha), but averaged only 422 lb/acre 

 (473 kg/ha). An average 39 percent of this was shrubs, 

 46 percent forbs, and 15 percent graminoids. What little 

 vegetation was produced was generally considered good 

 forage, with 51 percent in the desirable category. The 

 type thus has relatively low value as livestock range 

 because of sparse production. It appears to be of moder- 

 ate value as wildhfe habitat. Although undergrowth 

 production is poor, considerable diversity exists in both 

 overstory and undergrowth structure. 



This serai aspen type has not been noted outside of 

 Utah. 



Populus tremuloides-Abies concolor/ 

 Juniperus communis Community Type 

 (POTR-ABCO/JUCO c.t.) 



This is primarily a southern Utah serai community 

 type that was encountered principally in the Tushar 

 Mountains and high plateaus to the south. We also 

 observed the type at several locations on the south slope 

 of the Uinta Mountains in northern Utah. The 20 stands 

 sampled occurred at elevations between 7,400 and 

 9,200 ft (2 260 and 2 800 m), usually on less than 25 per- 

 cent slopes, and were not restricted by exposure. The 

 type appears adapted to a wide variety of soil parent 

 materials. 



The POTR-ABCO/JUCO c.t. represents the drier seg- 

 ment of aspen stands that are successional to Abies 

 concolor coniferous forests. The type is characterized by 

 the conspicuous presence and potential dominance of 

 A. concolor or Picea pungens in the tree overstory and a 

 distinct low shrub layer dominated by Juniperus 

 communis. Although Symphoricarpos oreophilus may be 

 present in the shrub layer, it is usually of lesser abun- 

 dance. The herbaceous undergrowth consists of a varia- 

 ble assortment of such graminoids as Stipa occidentalis, 

 Bromus anomalus, Carex rossii, and Sitanion hystrix, 

 and such forbs as Astragalus miser, Achillea millefolium, 

 Frageria vesca, and Thalictrum fendleri. 



The natural succession process leads to dominance by 

 A. concolor or P. pungens or both in the tree layer and 

 subsequent suppression of undergrowth production by 



36 



