REPRODXJCTION OF WESTERN YELLOW PINE. 141 



MISCELLANEOUS ENEMIES. 



Regarding the agencies classed in this category, practically nothing 

 new has been brought to light by this investigation. The fire situ- 

 ation, though always fraught with grave possibilities, is sufficiently 

 well under control so that it need not be a cause for alarm. Diseases, 

 insects, and rodents take an annual toll which in the aggregate must 

 be an important factor in natural regeneration of the forest; but 

 aside from guarding against unusual outbreaks, nothing can be done 

 at the present time to check their depredations. 



RULES FOR REPRODUCTION OF WESTERN YELLOW PINE. , 



The most essential deductions in this investigation may be epito- 

 mized in the following general rules : 



Encourage advance reproduction by instituting rigid protection 

 against fire and grazing damage 10 years before a proposed cutting. 

 Graze by cattle or horses sufficiently to hold grasses in check, but 

 avoid overgrazing. Until it is demonstrated that sheep can be grazed 

 with consistent safety to pine seedlings, they should be excluded from 

 areas which are being restocked. 



If adequate advance growth occurs at the time of cutting, leave 

 in addition to blackjacks only such trees as are needed for fire insur- 

 ance and to seed up stump patches. If reproduction is lacking at 

 the time of cutting, at least 4 good seed trees per acre above 20 

 inches in diameter should be left, unless natural conditions are known 

 to be favorable, in which case the number may be reduced to 3. 



Burn the brush after logging wherever tall grass or other luxuriant 

 ground cover occurs, and in all cases where reproduction is estab- 

 lished, unless the brush is distinctly needed to check erosion. Where 

 ground cover is light or of low stature, the brush may be scattered 

 or pulled, though piling and burning is usually preferable. On com- 

 pact soils, where ground cover has been destroyed, and on other bare 

 soils, scatter the brush lightly. 



Keep out fire ; kill rodent pests, including porcupines, gophers, rats, 

 pine squirrels, rabbits, chipmunks, and mice; be on the lookout for 

 disease and insect infestations. 



