36 BULLETIN 1491, U. S. DEPARTMENT OF AGRICULTURE 
realized both in a greater number of standing trees and in less defect 
in the timber grown. 
If the timberland owner attempts to produce full timber crops he 
must, in addition, somewhat modify his methods of cutting. It may 
be well to summarize briefly in this connection the silvicultural meas- 
ures proposed : 
1. The general principle should be to cut not over 50 or 60 per 
cent by volume of the timber at one time. The largest trees of the 
better "species should be cut out and the thrifty smaller trees left to 
grow in size and value and to be cut later. The inferior species 
or the poorer specimens in all sizes and types should be cut out as 
far as possible so as to eliminate them from the stands. The practice 
of cutting in advance of the other timber certain selected and valu- 
able species in the stand, such as ash, hickory, black walnut, and 
yellow poplar, should be stopped. To maintain or increase the pro- 
portion of ash, red gum, and yellow poplar in the stands, it appears 
necessary to clear-cut over small areas, or at least to cut the timber 
more heavily than 50 or 60 per cent by volume. 
2. In virgin or only lightly culled stands of the upland hardwood 
type, the valuable species should be cut to a diameter of 18 or 20 
inches, and the less valuable species to the lowest merchantable 
diameter. 
3. In mixed stands of pine and hardwoods, as well as in stands 
of nearly pure pine, the pine should not be cut to a smaller diameter 
than 12 or 14 inches. On south slopes and ridges all hardwoods 
should be cut. On north slopes thrifty hardwoods under 18 or 20 
inches may be left. 
4. In mixed stands of red cedar and hardwoods the cedar should 
be cut to fence-post sizes, leaving scattered larger trees to bear 
seed. All hardwoods interfering with the growth of the cedar 
should be cut. 
5. In the bottom-land type the diameter limit for the valuable 
species is 24 to 30 inches. If this high diameter limit can not be 
maintained, the stand should be cut clean of all stems except even- 
aged groups or patches of young, rapidly growing, and valuable 
species. 
6. Badly culled, burned, and grazed stands must first be rejuve- 
nated by excluding grazing animals, by preventing fires, and in 
some cases by forest planting. When a young growth is established, 
the decadent and broken trees can be removed. 
It is not possible to estimate closely the extent to which the 
observance of these measures will improve the quality of a forest 
or wood lot, but it is certain that the owner will approach closely 
the maximum return from his land and the best price for his prod- 
ucts. He can not expect immediate effects either from protection 
against fire and grazing or from cutting only' a part of the timber 
in logging operations. There will be no overnight change in the 
character of the timber or in its growth. A period of years must 
elapse before results will become evident. It is reasonably certain, 
however, that his property will gradually develop to the point of 
yielding each year the equivalent of 100 board feet an acre on the 
poorest soils and 500 or 600 board feet on the best. That means that 
at the end of each 10-year period 1,000 board feet, or its equivalent 
