22 BULLETIN 1264, U. S. DEPARTMENT OF AGBICULTUBE. 



the spring and the fall have proved very unsuccessful chiefly on this 

 account. On Mink Creek, the 1917 plantations in burned sage- 

 brush are very poor, on account of the dryness of the summer of 

 that year. The 1916 plantations on the same site were moderately 

 successful the first year but show excessive subsequent loss. The 

 Kock Creek plantations are generally rather poor. 



Growth naturally averages higher on the older plantations, where 

 it normally increases from year to year. Current growth in excess 

 of 1 inch a year is found in oak brush, where large 3-0 stock was 

 used (with very low survivals also in oak sage, cleared sage, a 

 Douglas-fir burn, one plantation under aspen, cleared aspen." and 

 temporary brush. These sites are characterized by plenty of light 

 coupled with soil conditions that run above the averaged In Big 

 Cottonwood Canyon, growth exceeds 1 inch per annum in three 

 temporary brush plantations, while at Beaver Creek the best show- 

 ing is in oak and cleared sagebrush. On the Mink Creek watershed, 

 excellent growth is found on the same sites in temporary brush, where 

 survival is best. 



The oldest extensive plantation of which a record of both survival 

 and height growth is available, was made in the fall of 1912 in the 

 permanent brush type on the southern aspect opposite the Cotton- 

 wood Xursery. At the end of eight years this plantation showed 

 50 per cent of the trees alive with an average height of 13 inches. 

 Another plantation made at the same time but on a less rocky site 

 on the same aspect showed about the same survival and an average 

 height of over 22 inches, the growth being about S 1 ^ inches each 

 year. The greatest proportion of the losses occurred during the first 

 two years after planting. The plantations of 1919 and 1920 show 

 plainly that the success of western yellow pine planting on either 

 the permanent or the temporary brush lands depends quite largely 

 on the amount of rainfall during the first season following planting. 

 The season of 1919 was unusually dry. and consequently the mor- 

 tality of the plantations of that year ranged from 47 to 77 per cent. 

 On the other hand, the season of 1920 was favorable in available 

 moisture and the mortality ranged from 8 to 15 per cent. 



A study of all the western yellow pine plantations in the inter- 

 mountain region leads to the following conclusions : 



1. Western yellow pine plantations can be successfully estab- 

 lished in the temporary brush type of the region, although results are 

 frequently none too good because of the severity of this class of sites. 

 as compared with those in other timber-producing regions of the 

 West. Ample rainfall during the first season following planting is 

 very frequently the one important factor which decides between 

 success or failure. Although many of the temporary brush lands are 

 potential Douglas-fir sites, western yellow pine, which is capable of 

 withstanding the unfavorable site conditions better than Douglas fir, 

 is more suitable for planting. If forest conditions were established, 

 the site would undoubtedly become favorable for the natural invasion 

 of Douglas fir. 



2. The successful planting of western yellow pine on the per- 

 manent brush lands requires a careful weighing of the factors of 

 cover, altitude, and moisture supply to secure the proper balance 

 between survival and growth. Of the sites in the permanent brush 



