ASPKN AS A TEMPORARY FORKvST TYPK 295 



spruce or lodgepole pine, even though fires are prevalent." If such is 

 the case, the tree is of course truly permanent. 



The position of the aspen in relation to the other types found on 

 the mountains of the Great Basin is given in the article, as it appears 

 typically on Boulder Mountain, in the Powell Forest, between the 

 aspen and alpine fir mixed and the yellow pine or oakbrush type. It 

 will be noted that no mention is made of a Douglas fir-white fir type 

 in this list. This widely recognized type also occurs between the lower 

 part of the Engelmann spruce-alpine fir type, designated in the list re- 

 ferred to as the aspen and alpine fir mixed type, and the yellow pine or 

 oakbrush type. On Boulder Mountain the Douglas fir-white fir type 

 is entirely lacking, however, its place being taken by pure aspen. In 

 fact, in the greater part of the Great Basin region the lowest extremi- 

 ties of this belt are as a rule nearly pure aspen. 



Nevertheless, there is ample evidence that this condition cannot be 

 accounted for by any unsuitability of the sites, but rather by tlie lack of 

 seed trees, as repeated fires have eliminated the conifers adai)ted to 

 these sites. Indeed, on parts of the Powell National Forest not far 

 from Boulder Mountain, as along the Winder-Escalante road, aspen is 

 an exceedingly rare species and much less does it appear in pure stands. 

 The road referred to is in the aspen and alpine fir mixed type where it 

 crosses the divide, below which it passes into an open type of Douglas 

 fir, with western yellow pines on drier and warmer situations and some 

 aspen scattered throughout. Below is the pure western vollow pine as- 

 sociated with oak. 



That both Douglas fir and white fir are able to grow in the belt be- 

 tween alpine conifers and the western yellow pine-oakbrusli ly])c is 

 apparent in all parts of the region. Douglas fir is associated even 

 with pifion-juniper l)c'l()\v the yellow pine-oakbrush ty])e in ])laces, as 

 on the south edge of the Manti Forest, in the canyon of the ICast 

 Fork of the Sevier River, in the vicinity of Birch and Escalantc creeks, 

 on the Powell Forest, and in the neighborhood of the Utah Experiment 

 Station. In the last locality white fir also is found scatteringly in many 

 parts of the oakbrush zone. At its upper limits Douglas tir i)enetrates 

 well into the spruce-fir type, although w-hite fir stops rather abruptly at 

 the lower limits of Engelmann spruce. The whole "permanent" aspen 

 belt therefore seems entirely suited climatically to these two conifers. 



A concrete example of this suitability is shown in Gooseberry Valley, 

 which has been pointed out as a typical permanent stand, the aspen 

 covering a large valley in absolute purity. Over a ridge to the north 



