THE EED SPRUCE. 49 
lating or saw-toothed, like a series of wedges or triangles with, their 
bases on line. This modification is rather commonly used with 
spruce abroad. 
Effectiveness in securing reproduction with the strip plan will 
depend upon the width of the strips employed. Satisfactory restock- 
ing of the cleared area can not be expected on a strip wider than twice 
the height of the trees in the adjacent stand; not because of inabil- 
ity to secure effective seed dispersal at even a great distance, but 
because of the effect upon seed germination and growth. Too exten- 
sive cutting will expose the soil to drying influences detrimental to 
spruce reproduction and at the same time create a condition favor- 
able to the development of hardwoods, raspberry, and other peren- 
nials and weed growth in general. 
Satisfactory reproduction in the reserve strips must be secured as 
advanced growth from seed trees standing on those strips, or the 
cutting of the reserve strips must be delayed until the trees on the 
strips first cleared are large enough to supply the necessary seed. A 
spruce stand in which windfirmness has been especially developed by 
periodic thinning from early youth may be reproduced by the shelter- 
wood compartment method. Such stands, however, can hardly be 
said to exist in this country at the present time. Thinnings of the 
severity of shelter-wood cuttings are largely out of the question in the 
previously unthinned stands of either virgin or old-field spruce which 
it is desirable to manage under a system of clean cutting in strips. 
To insure an early second cut and prompt and effective regenera- 
tion, alternate cut and uncut strips not over 75 feet in width should 
be employed. By the adoption of strips of this width reproduction 
would not only be reasonably assured to the cleared strips but the 
side light and extra ventilation which would be let into the uncleared 
strips would be sufficient to create a condition favorable to satisfac- 
tory reproduction there also. For the dense, even-aged, old-field 
stands, strips as narrow as 10 feet with 20-foot reserve strips inter- 
vening have been recommended. 1 The final clearing of the area under 
such a system should be possible within 10 or 15 years after the first 
cut. This will enable the harvesting of a third or more of the crop at 
one cut. The cost will of course be somewhat more than if wider 
strips or clean cutting in a solid block were practiced. The yield and 
operating cost per unit of area should not, however, be materially 
different from that which would result from cutting to a diameter 
limit of 14 inches, except that slightly greater expense would attach 
to the handling and marketing of the smaller material which the clean 
cuttings would yield. 
J " Forestry in New England," by R. C. Hawley and A. F. Hawes, p. 226. 
84949°— Bull. 544—17 4 
