REVIEWS 591 



detailed study was made of 150 sample plots. In 19 12 additional plots 

 were studied. In all. 250 plots were studied in detail within 25 miles 

 of Flag-staff, Arizona. The study of the sample plots was supplemented 

 by general observations extending over a period of two years on other 

 forests in Arizona and Xew Mexico. The plots were located so as to 

 include the following range of conditions : 



(i) Areas embracing all conditions of range noi;mally grazed by 

 different classes of stock. 



(2) Areas embracing all conditions of range overgrazed by dift'erent 

 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 b\- all 

 classes of stock. 



(5) Areas supporting chiefly bunch grasses, grazed by dift'erent 

 classes of stock. 



(6) Areas where cattle congregate. 



(7) Areas where sheep congregate — /. c, along driveways and on 

 bed grounds. 



Studies made on these plots at requisite intervals showed that 42 per 

 cent of the total number of trees observed are damaged to some extent 

 annually, and that 16.7 per cent are subject to severe damage under the 

 grazing conditions prevailing over at least one-half of the yellow-pine 

 type on the Coconino Forest. The greater amount of damage occurred 

 during the latter half of June and early in July and the least during the 

 first few weeks of the grazing season. During periods most fa\orable 

 for the growth of forage there is usually little damage. The pine 

 shoots are succulent and tender prior to the middle of August and con- 

 sequently are more palatable than later in the year. The damage in any 

 year is practically confined to the growtii of the year. 



Although all classes of stock are likely to damage yellow-pine repro- 

 duction, it is believed by the writer that horses and burros may be elimi- 

 nated from the classes of stock responsible for severe damage. Al- 

 though damage by cattle is everywhere a])i)arent, the greatest damage is 

 done by sheep, as set forth in a table showing a comparison of cattle 

 and sheep damage. Sheep are found to do approximately yYz times as 

 much damage as cattle. 



The (lata collected from these interesting rei)r()duction studies show 

 that yellow-pine reproduction is not eaten by stock through preference 

 when palatal)le forage is a\ailabli', but when ])alatal)Ie forage is not 

 sufficient for the classes of stock on the range, which is often the case, 

 yellow-pine reproduction is likely to be seriously damaged. 



