Figure 15.— The minor 

 though wide-ranging 

 Populus tremuloides- 

 Pinus ponderosa/Juniperus 

 communis c.t. represents 

 one of the driest aspen 

 types successional to 

 coniferous forests. This 

 stand on the Markagunt 

 Plateau, Dixie N.F., has 

 typically sparce under- 

 growth in which 

 J. communis, Poa 

 fendleriana, Sitanion 

 hystrix, Antennaria rosea, 

 and Achillea millefolium 

 are prominent species. 



S. oreophilus habitat type (Youngblood and Mauk 1985) 

 of central and southern Utah. 



Production was sampled on only one stand in this 

 type. Tree basal area was 193 ft^/acre (44.3 m^/ha) in this 

 stand, which appears to be high for the P. ponderosa cli- 

 max forest series. Conifers were 42 percent of the basal 

 area. Aspen site index at 80 years was a fairly high 57 ft 

 (17.4 m). Reproduction was low for both aspen and 

 conifers. Only 450 aspen suckers/acre (1 114/ha) and 51 

 conifer seedlings/acre (127/ha) were counted. 



Undergrowth production was a low 428 lb/acre 

 (480 kg/ha). An unusually high 65 percent of this was 

 graminoids, 15 percent forbs, and 20 percent shrubs. 

 Though meager in amount, the undergrowth was highly 

 rated as livestock forage, with 55 percent classed desira- 

 ble and 43 percent as intermediate suitability. The high 

 proportion of grasses makes this type better suited as 

 cattle range than as sheep range. Wildlife habitat values 

 appear low to moderate because of limited structural and 

 species diversity of the vegetation. 



This serai aspen type has not been reported to occur 

 elsewhere. 



Populus tremuloides-Pinus contorta/ 

 Vaccinium scoparium Community Type 

 (POTR-PICO/VASC c.t.) 



This minor, local type occurred only on the north 

 slope of the Uinta Mountains in northern Utah. The six 

 sampled stands occupied only soils of quartzite origin. 

 They grew at elevations between 7,700 and 9,100 ft 

 (2 350 and 2 770 m). 



The community type is characterized by the abun- 

 dance of Pinus contorta associated with Populus 

 tremuloides in the overstory and a low shrub complex 

 dominated by Vaccinium scoparium or possibly 

 Vaccinium caespitosum. Frequently Abies lasiocarpa 

 may also be present in the tree layer but only in minor 

 amounts. Shrubs likely to be encountered in the under- 

 growth associated with the Vaccinium spp. include 

 Berberis repens, Pachistima myrsinites, and Juniperus 



communis. The only herbaceous species with high con- 

 stancy and coverage is the sedge Carex geyeri. Other 

 herbs often present in varying amounts include 

 Osmorhiza chilensis, Galium boreale, Elymus glaucus, 

 Trisetum spicatum, Lathyrus spp.. Arnica latifolia, and 

 Antennaria microphylla. 



Mauk and Henderson (1984) recognized a P. contorta/ 

 V. scoparium c.t. in the Uinta Mountains that resembles 

 our POTR-PICO/VASC type. P. contorta is more shade 

 tolerant than P. tremuloides and will eventually domi- 

 nate these stands. Abies lasiocarpa, on the other hand, 

 is more shade tolerant than P. contorta and where 

 adapted will eventually replace P. contorta. Mauk and 

 Henderson (1984) suggest that on some sites the 

 P. contorta/V. scoparium c.t. reflects true climax vegeta- 

 tion and thus qualifies as a habitat type. On other sites 

 this conifer type appears to be a successional stage 

 within an A. lasiocarpa/V. scoparium habitat type. Thus, 

 it appears that the POTR-PICO/VASC c.t. is a serai 

 stage within both the P. contorta/V. scoparium and 

 A. lasiocarpa/V. scoparium habitat types. In any event, 

 the natural course of succession on these sites will lead 

 to the demise of the aspen overstory and conifer 

 dominance. 



This minor type was not sampled for production. We 

 assume, however, that tree growth may be approxi- 

 mately the same, if not slightly greater, than the 

 135 ft'/acre (31.0 m^/ha) basal area in POTR-PICO/JUCO 

 type. Aspen site index in this latter type was a low 42 ft 

 (12.9 m) at 80 years. Undergrowth production also may 

 be similar to the low 603 lb/acre (677 kg/ha) found in the 

 POTR-PICO/JUCO c.t. The POTR-PICO/VASC c.t. is 

 relatively poor livestock range and of no more than 

 moderate value as wildlife habitat. 



Although this serai type has not been reported else- 

 where, it probably can occur in Colorado. We believe 

 that this type is probably serai to the A. lasiocarpa/ 

 V. scoparium habitat type (Mauk and Henderson 1984) 

 in Utah; P. tremuloides is cilso recognized as a serai tree 

 in the same habitat type in northwestern Colorado (Hoff- 

 man and Alexander 1980, 1983). 



39 



