296 JOURNAIv OF FORESTRY 



lies a parallel valley, similar to (jooseberry A'alley as to slope, exposure, 

 and elevation, but with a very slightly rougher topography. Upon a 

 few rocky outcrops stand groups of white iir and Douglas fir seed 

 trees, around which in the aspen thrifty reproduction is coming in. 

 The reason for the "permanence" of the Gooseberry Valley aspen is 

 apparently due merely to the complete elimination of all seed trees. 



The proposition that, owing to the vigor of sprout reproduction and 

 the density of the resulting stands, the aspen is able to choke out the 

 conifers and thus maintain its supremacy, does not appear to be sound, 

 even in the Great Basin. Clements^ in discussing western tree species 

 places aspen higher even than western yellow pine in a list of trees 

 arranged in the order of their tolerance. Suppression of conifers by 

 aspen has never been observed by the present writer. On the other 

 hand there nc a great many examples of conifers doing well under 

 dense aspcu shade. 



On the clear cut plot at the Experiment Station to which reference 

 is made in the article upholding the permanence of aspen, there were a 

 number of small conifers before cutting, alpine fir, blue spruce, and 

 limber pine, all of which are in a thrifty condition at the present time 

 in the jungle of 5-year-old sprouts. It also appears that the author of 

 the article may have been misinformed when he states that when 

 heavy stands of aspen at the Experiment Station are underplanted 

 they have to be thinned. It is true that one heavy stand was thinned 

 for experimental purposes, and that it resulted in a stimulated growth 

 of the planted conifers, coupled, however, with a greater annual loss 

 than in the unthinned portion. In dense stands the growth of native 

 conifers is retarded, to be sure, but death from suppression is rare. 

 The effect of aspen cover upon trees planted at the Experiment Station 

 is shown in a number of cases below. Light intensities given were de- 

 terminated with a Clements photometer, the values being based on full 

 sunlight as i.oo. 



Plantations Made in Spring of 1916 



Light intensit)' .10 .51 



Species — Per cent living, fall of 1917 



Western yellow pine 76 69 



Douglas fir 60a 57 



Norway spruce 81 44 



a Moisture conditions much the best on thinned area. 



' Clements, Frederic E. : "Plant Succession." Pub. 242, Carnegie Institution, 

 Washington, 1916. 



