34 



SIEREA REGIOX, 



Sugar pine and 3'ellow pine are more valuable than Douglas fir in 

 this region, and consequently Douglas fir should be cut close and a 

 preponderance of sugar and yellow pine seed trees should be left. 

 The pine seedlings, which are much less tolerant than Douglas fir, 

 make good growth in the increased light afforded by the thinnings, 

 and can then cope on equal terms with the fir. "\Aliere, as is commonlj' 

 the case near streams at the lower elevations, Douglas fir keeps to the 

 gulches and pine to the ridges, heavy thinning of the fir and reten- 

 tion of all the pines necessary for seed at the tops of the slopes will 

 tend to increase the proportion of the pines. Since pine cones require 

 two years to mature and those of Douglas fir but one, the probability 

 of a good seed crop can be estimated farther in advance for the pines 

 than for Douglas fir. Cuttings can, therefore, be planned which will 

 be immediately followed b}^ a heaw^' fall of pine seed, and the chances 

 for a good stand of pine reproduction increased. The number of pine 

 seed trees may be reduced in anticipation of such a seed year, while 

 in years of scant seed production a proportionately greater number 

 should be left to insure an immediate restocking. 



^"Miite fixr and incense cedar are generally of less value than Doug- 

 las fir, but are at the same time more tolerant of shade, ^^"lien they 

 grow in mixture with Douglas fir they should therefore be cut to 

 the lowest possible diameter limits, while the cutting of the more 

 valuable sugar and yellow pines and Douglas fir should be restricted 

 to a higher minimum diameter. 



NORTHERX ROCKY MOUXTAIX REGIOX. 



This region is characterized by a multiplicity of forest types and 

 subtypes. The different conditions of these types call for distinct 

 methods of management, and silvicultural rules are not so widely 

 applicable as in the preceding type. 



The more valuable species in this forest which are to be favored 

 in management are western white pine, Douglas fir, western larch, 

 western yellow pine, Engelmann spruce, and giant arborvita?. The 

 other species of this region are of less commercial value, and should 

 be discriminated against in marking for cutting wherever they grow 

 in mixture with the better species. Lowland fir and western hem- 

 lock are especially undesirable in mixture with Douglas fir, owing 

 to their greater tolerance of shade and consequent ability to drive out 

 the Douglas fir. Lowland fir generally grows more rapidly, at least 

 in 3^outh, than the Douglas fir of this region, and on situations favor- 

 able to both is alwaj^s a menace to the latter species. Where it pre- 

 dominates in the' stand, the less tolerant white pine, Douglas fir, and 



[Cir. 150] 



