48 THE SEED TREE METHOD 



nursery. But after five years growth in field plantations, 

 seedlings from conky trees exceed those from soimd trees in 

 height growth. This particular fungus on Douglas fir, as it 

 attacks only heartwood, may not affect the vitality of the 

 tree. 



Pearson's study of " the Influence of Age and Condition of 

 the Tree upon Seed Production in Western Yellow Pine," ^ 

 indicated that those affected with heart rot were apt to have 

 a slightly higher germination per cent than sound trees, while 

 mistletoe reduced the germination per cent. Seed from young 

 trees (below 140 years) gave a higher germination per cent 

 than that from older trees. Nothing is reported as to the 

 quality of the seedlings produced by seed from these various 

 classes of trees. 



After fixing upon the kind of seed trees to be left the num- 

 ber per acre must be decided. The amount of seed produced 

 per tree and the distance to which seed can be disseminated 

 are among the principal determining factors. The very nature 

 of the method requires that it be applied only with relatively 

 light seeded species relying upon wind dissemination of the 

 seed. Ample seed to restock aU portions of the area must be 

 provided. As a general rule with light seeded species satis- 

 factory dissemination of seed can be counted on for a distance 

 from the tree at least equal to the height of the tree. With 

 large sized individuals of a decidedly light seeded species one 

 tree per acre may be enough. The same species in small 

 sized second growth timber may require ten per acre. A 

 prolific seed producer, but with a heavy seed may need a 

 similar number to insure uniform distribution. With site 

 conditions favorable to germination and establishment of 

 reproduction fewer seed trees will be needed than if the 

 reverse is true. The necessity of securing reproduction either 

 in one or during several seed years and whether the seed 



