48 BULLETIN 1402, U. S. DEPARTMENT OF AGRICULTURE 
At one extreme is the yellow pine type with 53.8 per cent and 
53.1 per cent of area provided for in the two cases analyzed. At 
the other extreme is the group of fir types with 89.7 per cent of the 
forties provided for and many with six or more seed trees per acre. 
Between these two come the yellow pine-sugar pine type and the 
yellow pine-white fir type with 76.3 per cent; yellow pine-Doug- 
las fir with 81.5 per cent; mixed conifer with 87.9 per cent; and 
sugar pine-fir with 88.2 per cent. (Fig. 20.) For all except 
the pure yellow pine type, it appears therefore that there are on 
PE:RCE1NTA6E: of area. PROVIDEID with SEIED TREIES 
20 40 60 80 100 
Fig. 20. — Average ability of various types to restock when cut to a 20-inch diameter limit. 
The inadequacy of restocliing in the pure yellow pine type, with only 53.1 per cent of the 
area provided with seed trees, is in strong contrast with most of the other types. The 
bars also indicate the relative volume in trees over 20 inches in diameter that must be 
left to bring the different areas up to full production 
the ground at the time of logging sufficient small seed trees 18 and 20 
inches in diameter to restock at least three-fourths of the area. 
AVhether or not the 20-inch diameter limit method is the best 
means of insuring the restocking of cut-over lands, it is clear that 
it is a workable method. 
THE STUMPAGE INVESTMENT IN SEED TREES 
The investment in wood represented by the small trees left by 
cutting to a 20-inch diameter limit has already been indicated. It 
remains to be considered whether the money value represented by 
the small trees is actually obtained when the trees are logged, or 
whether it is not more profitable to the logging operator to leave 
the small trees on the ground. 
