448 forestry Quarterly. 



4. The better qualities are for the most part a medium to deep 

 loamy soil, with a mixture of sand or gravel. 



5. The poorer qualities occur upon soils, for the most part, 

 either a shallow or very shallow sand with a rock subsoil, with 

 much outcropping rock. 



6. The best quality sites in Washington occur below 1000 feet 

 elevation; in Oregon below 1700 feet; both in the region of great- 

 est precipitation and most even temperature. 



7. The poor quality sites occur above 1200 feet in Washington ; 

 in Oregon no doubt at much higher elevations. 



8. The medium or second quality sites are found at interme- 

 diate elevations' between the best and the poorest qualities. 



9. Douglas fir is found mainly in pure stands either on bench 

 or slope lands which are well drained, while the poorer drained 

 bottom land stands contain a mixture of Hemlock and Cedar with 

 the Fir. 



4. The Influence of Aspect upon the Density and Growth of 

 Douglas Fir. In general it has been noted that stands with cer- 

 tain aspects appear to be either more or less densely stocked than 

 similar stands situated on different aspects. The study shows 

 that this is actually the case, and not only is the density of the 

 stand afifected, but also that the cubic volume, the board-foot vol- 

 ume, the basal area, and the diameter growth are affected. 



1. A south exposure bears the densest stocked stands; a north 

 exposure bears the least densely stocked stands. 



2. The trees on a north exposure have a greater diameter 

 growth, and the growth in cubic feet and board foot volume ex- 

 ceeds that of other exposures. 



3. The trees on a south slope, having a smaller diameter give 

 a larger basal area in square feet than those on other exposures. 



5. Influence of Density of Stocking on Growth and Volume. 

 In order to attain the maximum yield in bpard measure, it is de- 

 sirable to thin out most of the smaller, suppressed trees and thus 

 give the larger ones a chance to attain the best development pos- 

 sible under the conditions. 



Mr. Hanzlik illustrates this with two otherwise similar tracts 

 located in the Coast Range. Both are on Quality I sites and 



