EANOE MANAGEMENT ON THE NATIONAL FORESTS. 27 



range as a whole. The main precautions necessary and the reasons 

 for them are presented on page 66. 



ACREAGE REQUIRED FOR SHEEP AND CATTLE. 



A number of grazing-capacity studies have been conducted to 

 determine the minimum acreage required to support a cow or sheep 

 through the grazing season. The acreage grazed over, the intensity 

 of grazing, the length of the grazing season, and the methods of 

 management of both range and stock have been closely- observed and 

 recorded by men giving special attention to the work. To supple- 

 ment these special studies, the data secured from grazing recon- 

 naissance surveys during the past six years have been carefully 

 analyzed. The data from the two sources appear to be consistent 

 enough over a wide range of territory to warrant conclusions as to 

 the approximate average acreage requirement for cattle and for 

 sheep. It is believed that the figures which follow will be of mate- 

 rial value in bringing about greater uniformity in the quantity of 

 usable forage made available for each animal or for each band or 

 herd over individual Forests and over the Forest ranges as a whole. 

 It is not intended that they should apply to a small range unit or 

 part of a unit with the accuracy finally desired. The first big step, 

 however, in adjusting grazing capacity is to equalize the distribution 

 of forage and stock over large units. After this is done the final 

 grazing capacity on individual ranges will have to be worked out 

 by adjustments from time to time over a period of years until the 

 number of stock is such as to utilize all the forage as closely as it 

 should be used on the individual range, all factors considered. 



ACREAGE FOB, SHEEP. 



Fifty-six sheep allotments on summer range have been carefully 

 studied during the past few years. An average of 2.5 acres, or 0.79 

 forage acres, 1 was required to support 1 mature sheep or 2 lambs 



1 The variation in amount of forage per acre and the relative palatability of forage 

 plants are important factors in determining the amount or volume of forage which stock 

 can be expected to use on a given range, and consequently in determining the grazing 

 capacity of the range in question. To determine the comparative amount of forage by 

 range reconnaissance methods, the range is classified into types, and for each area of a 

 given type the stand of forage which stock shonld use is estimated. A complete ground 

 cover made up of vegetation palatable to stock is represented by 1.0. Variation from this; 

 standard is represented by the decimals 0.95, 0.90, 0.85, and on down to 0.1. The actual 

 acreage of a given area, multiplied by the decimal representing the stand of forage gives 

 the amount of forage which it is estimated tbat stock will secure. For example, on an: 

 area of 100 acres, where the forage factor is estimated at 0.5, there are 50 units of 

 forage produced. The unit of measure in this case is called a forage acre, and in the 

 example given there are 50 forage-acre units on the 100 surface acres of range. This 

 method of arriving at the grazing capacity of range is not in general use and therefore 

 is not emphasized in the text. It is used, however, by grazing experts who have been 

 trained in range reconnaissance surveys and estimates, and for this reason the forage- 

 acre requirements of range stock are given. 



