A CRITERION OF SITE 259 



on site II alone were decidedly xerophytic. The increment on 

 site I amounted to 64% more than that on site II. The in- 

 dividual growth and development, luxuriance and density of the 

 vegetation varied decidedly with site. The vegetation on site I 

 was more luxuriant and vigorous than on site II where it was 

 comparatively sparse. A rather cursory comparison of the forest 

 vegetation of various sites within the range of the Rocky Moun- 

 tain variety of western yellow pine (Pinus ponderosa scopulorum) 

 occurring in New Mexico, Arizona, Utah, and Colorado shows 

 certain striking parallelisms and at the same time differences 

 which can only be attributed to site. Again chaparral areas 

 composed of Quercus gambelii, Amelanchier alnifolia, Arcto- 

 staphylos pungens, Ceanothus fendleri, and other shrubby species 

 are reputed by some to be potential western yellow pine sites. 

 An examination of such areas in the Intermountain Region re- 

 veals few western yellow pine associates among either the shrubby 

 or herbaceous vegetation, which results in the attaching of 

 considerable doubt to the statement that such areas are poten- 

 tially western yellow pine sites. 



In central and southern Utah between elevations of 6500 and 

 7800 feet above sea level Quercus gambelii is the dominant 

 species on all exposures except the south, with Amelanchier 

 alnifolia, Prunus inelanocarpa, Rosa fendleri, Acer grandidenta- 

 tum, Symphoricarpos oreophihis, Berberis repens, Purshia tri- 

 dentata, Pachyslima myrsinites, and Artemisia tridentata occurring 

 in varying mixtures. In the brush scattering individuals of 

 Juniperus scopulorum, Abies concolor, Picea parryana, Pseu- 

 dotsuga taxifolia and very rarely a specimen of Pinus ponderosa 

 scopulorum may be found. When the nature of the soil as well 

 as the growth and reproductive power of Abies concolor and 

 Pseudotsuga taxifolia on these areas are considered they are 

 regarded as belonging to the potential fir type. On ridge-tops 

 and south slopes Arctostaphylos pungens, Peraphyllum ramosis- 

 simum, and Ceanothus fendleri become the dominants while 

 Quercus gambelii, Sy?nphoricarpos oreophilus, Amelanchier alni- 

 folia, Berberis repens, Cercocarpus parvifolius, Purshia tridentata, 

 Pachyslima myrsinites, Artemisia tridentata and Eurotia lanata 



