The Coconino sun., 1918-07-19
GRAZING, ITS EFFECT
 ON FOREST GROWTH

service, in charge of the Fort Valley experiment station, established few years ago for the purpose of getting accurate information as to "cause and affect" in the Southwestern timber belt, on tree growth. Much valuable work has been done, but it is only pioneer" work, for time is the great element in gathering actual facts. Many well spun theories have been exploded by actual experiments and a good working basis has been obtained by MT. Pearson during the past few years and the Fort Valley experiment station is rapidly getting a reputation as the most valuable institution in the forest service.
 In his summary, Mir. Pearson touches on a number of subjects of vital interest to the people of this sec tion of the country. His summary is as follows:
 This article should be regarded as a progress report on an investigation which is barely begun. Although val uable data have already been secured, the chief value of the work up to the present time lies in the devlopment of methods and the establishment of rec ords for future reference. Full returns will begin to be realized only after 20 or 30 years.
 The western yellow pine forests in this region are as a rule not fully stocked. The main reason for this is poor natural reproduction. Most prom inent among the agents responsible for the death or injury of trees past the sapling stage are mistletoe, in- sects, porcupine, lightning, and wind.
 Increment data cover too short a period to furnish reliable basis for calculating yield. The indications are, however, that an annual increment of two per cent of the growing stock on cut-over areas is conservative fig ure. In average stands this means an annual growth amounting to from 50 to 75 board feet. Where natural reproduction brings about rapid re- stocking, the above figures may be greatly exceeded during the first 40 years after cutting.
 Natural reproduction is the great est and most far-reaching silvicultur- al problem with which the forester has to contend in this region. In cer- tain sections reproduction is good, but on the national forests, where exploi- tation has been greatest, reproduction is generally unsatisfactory. This sit uation is due largely to natural condi- tions, foremost among which is insuf- ficient or poorly distributed precipi- tation. Silviculture can never wholly overcome the difficulty. All it can reasonably be expected to do is to throw the weight of mans endeavor on the right side of the balance, The extent to which management can be depended upon to expedite reproduc, tion is matter requiring further in, vestigation.
 Next to unfavorable climatic con, ditions, the factors most inimical tc reproduction of western yellow pine are fire, unregulated grazing, and in. sects.
 On extensive areas fire has vitiatec the efforts of the forest to perpetuatt itself. With the present fire protec tion system in effect, damage iron this source will in the future be great ly reduced. Notwithstanding this fact when it is considered that the recur renee of fire on given area once il twenty years may nullify all progress in reproduction, the importance of thi. factor can scarcely be overestimated
 Grazing animals, especially sheep are responsible for much damage. Or the other hand, grazing is beneficial in that it facilitates the control ot fires, aids germination by covering tree seeds, and decreases competition between tree seedlings and herbaceous vegetation. The solution of the graz. ing problem lies in regulation rather than exclusion of stock Since this is one of the few large factors capable of control, it demands serious atten- tion.
 Insect damage ranks with fire and grazing damage. Unfortunately, no practical means for controlling the in- sect enemies of forest reproduction in this region are at present available. l