UNITED STATES DEPARTMENT OF AGRICULTURE 
Contribution from the Forest Service 
HENRY S. GRAVES, Forester 
Washington, D. C. PROFESSIONAL PAPER December 21, 1917 
EFFECTS OF GRAZING UPON WESTERN YELLOW-PINE 
REPRODUCTION IN THE NATIONAL FORESTS OF ARI- 
ZONA AND NEW MEXICO. 
By Rosert R. Hirt, Grazing Examiner. 
CONTENTS. 
Page. Page. 
Importance of protecting pine reproduction. - 1 | Effects of grazing injuries upon western yel- 
Scope and method of study. ...-.....-.-..-- 2 low-pine reproduction ....-....-.---..-.26 16 
Extent of damage to western yellow-pine Summarys ocean peacock cae oe ee ee neers 23 
reproduct‘on from grazing.......-.....--.. 4 | Application of results to range management 
Factors influencing damage. ...-.. ees eRe 9 im The Southwest aericascrice eset cece siateeeise 25 
IMPORTANCE OF PROTECTING PINE REPRODUCTION. 
The best summer forage in Arizona and New Mexico is found 
among the open stands of yellow pine, mainly at elevations above 
6,000 feet, and covering more than 8,800,000 acres, or 6 per cent of 
the total area of the two States. (See map, fig. 1.) Every economic 
consideration requires that this forage, one of the region’s most 
important resources, should be converted into meat. At the same 
time, it is important that this should be done with the least possible 
injury to the yellow pine, which is by far the most important timber 
of the Southwest. In many places the tree is not reproducing satis- 
factorily, hence it is very necessary to protect the young growth 
(which in any event has to contend with severe winters, dry springs, 
and parasites and insects) from damage by stock. 
The problem is especially important in the National Forests, 
which are created primarily to conserve the timber supply and to 
protect the vegetative cover on the watersheds. “In the Forests is 
the bulk of the yellow pine in Arizona and New Mexico, and on the 
National Forest range ate grazed approximately 30 per cent of all 
the range stock in the two States. Stock use the Forest range mainly 
during the summer, from April to November. 
This bulletin presents the results of a study to determine the 
character and extent of the damage to young growth of western 
yellow pine in the Southwest from the grazing of live stock, and to 
find out the best means of keeping such damage at a minimum while 
permitting proper utilization of the range. 
4205°—17—Bull. 580-1 
