BULLETIN 580, U. S. DEPARTMENT OF AGRICULTURE. 





ietwo stares.. 151.000.000 A 



"*-*, \ -^ | JApprox aw of Western Yellow P^aSeOO.OOOA. 



Fig. 1. — Yellow pine in Arizona and New Mexico. 



SCOPE AND METHOD OF STUDY. 



An intensive study was made on the Coconino Xational Forest, 

 in the north-central portion of Arizona, where grazing and timber 

 conditions are typical of the forests of the Southwest, and where 

 the problem of securing satisfactory timber reproduction is often 

 serious. This was supplemented by general observations, covering 

 a period of two years, on other Forests in Arizona and Xew Mexico. 

 The observations were confined chiefly to the yellow-pine type, but 

 for purposes of comparison some observations were made in the 

 Douglas fir and pinon-juniper types. 



Early in the season of 1910 a preliminary reconnaissance was 

 made on the Coconino Forest. This was followed during that year 

 by a detailed study, in which observations were made upon 150 plots. 

 Further observations were made in 1912 on additional plots. Alto- 

 gether 250 plots were observed within a radius of 25 miles of Flag- 

 staff, in the heart of the Forest. 



The plots were located so as to include the following range condi- 

 tions : 



(1) Areas embracing all conditions of range normally grazed by 

 different classes of stock. 



(2) Areas embracing all conditions of range overgrazed by dif- 

 ferent classes of stock. 



(3) Areas supporting a good stand of forage normally grazed by 

 all classes of stock. 



(4) Areas supporting a poor stand of forage normally grazed by 

 all classes of stock. 



(5) Areas supporting chiefly bunch grasses, grazed by different 

 classes of stock. 



(6) Areas where cattle congregate. 



