48 PRACTICAL FORESTRY IN 



upon. This is a question of economy in logging operations, 

 lay of the ground, prevailing wind direction, fertility of the 

 stand and other local considerations. A valley with healthy 

 fir woods on either side is likely to seed up promptly even if 

 a half mile wide. So is a flat at the leeward foot of a hill 

 timbered on the summit where the wind strikes. A cutting 

 on a ridge is correspondingly unlikely to restock. Theoreti- 

 cally if a tract of timber were large enough, it could be opened 

 up by logging operations which, instead of proceeding steadily 

 from one edge, might skip every other landing or so until the 

 most remote portion was reached after a few years, and then 

 work back again, cleaning up the neglected portions after they 

 had seeded the first openings. The same effect sometimes re- 

 sults from actual accidental practice. 



It is apparent that rules cannot be laid down for general 

 application. Generally speaking, a logger interested in fir 

 reforestation should study his ground to see if naturally, or, 

 with inexpensive aid, the cut-over area will not reseed from 

 the sides and from the cull trees he will leave uncut. If not, 

 he may leave a few merchantable seed bearing trees provided 

 the soil is such as to make them deep-rooted and wind-firm. 

 Groups are better than single trees because less likely to be 

 blown down and easier to protect from the slashing fire. More 

 should be left toward the windward edge. But before tieing 

 up any considerable sum in merchantable trees he should con- 

 sider the cost and safety of supplementing any shortage of 

 natural supply by artificial seeding. 



WESTERN HEMLOCK (Tsuga heterophylla) 



Since hemlock is so frequently associated with Douglas fir, 

 the principles governing its reproduction and its relative 

 promise as a second crop have necessarily been largely covered 

 in the preceding discussion of fir. The following remarks are 

 merely additional. 



We have seen that the perpetuation of hemlock is advisabla 

 only where fir reproduction is difficult to obtain or will be at 



