36 



REFORESTATION ON THE NATIONAL FORESTS. 



TABLE 10. Number of seed required per acre. 



BROADCAST SOWING OVER THE WHOLE AREA. 



SEED-SPOT SOWING. 



[Spots 6 by G ; approximately 12 good 1 seed per spot.] 



1 For example, if the germination tests showed 50 per cent germination, 24 seed would have to be sown 

 to have 12 good seed. 



The germination period varies with weather conditions and with 

 the quality and kind of seed. The approximate number of days of 

 " growing " weather after sowing required by different species varies 

 from 14 to 22 days. The temperatures at which tree seeds sprout in 

 the shortest time lie between 66 and 68 F. 



PROTECTION FROM RODENTS. 1 



In some parts of the West farmers suffer heavy loss from rodents. 

 Toll is taken of seed grain by mice, squirrels, and pocket gophers, and 

 this in spite of the fact that the farmer sows as much as 100 pounds 

 of wheat to the acre and by annual plowing and further cultivation 

 renders conditions inimical to the domestic life of the rodents. When 

 under such conditions these little animals cause serious injury to 

 seed grain and to growing crops, it is but natural to expect much 

 greater damage when tree seed is sown. A rodent population suffi- 

 cient to eat or store 10 out of 100 pounds of wheat sown on an acre 

 could make away with all of the necessarily few pounds of tree seed 

 sown. The actual rodent population on wild land in or near the 

 woods is probably greater, and is certainly more varied, than in culti- 

 vated fields. Tree seed is very attractive to rodents and is more 



1 This subject is treated in Circular 78 of the Biological Survey, " Seed Eating Mammals 

 in Relation to Reforestation," from which the formulas given here are taken. 



