GRAZING AND FORAGE PRODUCTION ON NATIONAL FORESTS 



33 



Table 9. — Yield and longevity of plants harvested twice, two weeks after, 

 oeginning of growth and again at close of growing season, each year 



Plot No. 



Plant 



Zone 1 



Number of 

 plant 2 



Yield per plant 

 (grams) 



Yield per plot 

 (grams) 





1920 



1921 



1922 



1920 



1921 



1922 



1920 



1921 



1922 



S-9-16... 



SL-31-40 

 B-6 



Letterman needle grass 



._...do.._-. 



S-F 

 O-B 

 A-F 

 S-F 

 O-B 



8 

 10 



If) 



8 

 10 

 14 



8 



10 

 14 

 7 

 5 



0.95 

 5.45 

 .87 

 9.17 

 3.44 



1.51 

 1.97 

 5.06 



7.88 

 2.42 



1.44 

 2.94 

 4.56 

 10.55 

 9.83 



7.62 

 54.50 

 12.98 

 73.38 

 17.20 



12.09 



19.67 

 70.85 

 63.07 

 12.08 



11.50 

 29.44 

 63.89 



G-9-16... 

 G-6-10— 



~-~-~do~-~~~----------------- 



Total 



8 

 5' 



8 

 5 



73.85 

 49.16 





46 



45 



44 









165. 68 



177. 76 



227. 84 

















i Zones: S-F = Spruce-fir; A-F = Aspen-fir; O-B = Oak-brush. 



2 The number of plants shown in this table represents those living at the beginning of each year's treat- 

 ment. 



PLOTS HARVESTED EARLY AND LATE IN SEASON 



The results from removing the herbage early one season and late 

 the next are given in Table 8. Plots were harvested two weeks after 

 beginning of growth in 1920 and 1922, and six weeks after beginning 

 of growth in 1921. The aftermath was removed each year at the 

 close of the growing season. The results obtained show that one 

 moderately early grazing in alternate seasons does not impair the 

 vigor of the plants treated. 



The results of a somewhat similar method by which the herbage 

 was removed two weeks after growth began and again at the close 

 of the growing season each year are presented in Table 9. Not only 

 was the stand maintained well during the three-year test of this 

 method, but the yield was generally well sustained. Many of the 

 plants increased in the luxuriance of their growth. 



A somewhat similar but more drastic method of treatment was 

 used on a plot of mountain brome. The plot was harvested three 

 times a season, the first harvesting being made two weeks after 

 beginning of growth, the second just before seed maturity, and the 

 third at the close of the growing season. The plot contained 53 

 specimens at the beginning of the experiment in 1920, and 51 of these 

 were living in 1922. The average yield per plant was 51.45, 35.69, 

 and 51.96 grams for 1920, 1921, and 1922, respectively. Although 

 two of the plants were lost, probably caused by rodents and frost 

 upheaval, the yield for 1922 does not indicate any decrease in vigor. 

 On a plot of mountain brome where the second cutting was made 

 five weeks after the first, and in the other plots where the second 

 harvesting was made after longer intervals, somewhat similar results 

 were obtained. The interval between the harvestings was sufficiently 

 long to permit the vegetation to overcome any setback that might 

 have resulted from the one early harvesting. (PL III, fig. 2.) 



A system of grazing which provides for the cropping of the 

 herbage at the time of vegetational readiness or early in the season 

 will not be detrimental if the forage is not removed too closely and 

 subsequent croppings are not made before the vegetation has had 

 ample time to recover from the first grazing. 



