GRAZING AND FORAGE PRODUCTION ON NATIONAL FORESTS 29 



Table 5. — Results of harvesting five times each season 





Plant 



Yield 



per plot i (grams) 







1920 



1921 



1922 







86.11 



11.21 



63.15 



334.45 



894 18 



886. 20 



83.22 



19.19 



11.41 



128. 21 



16.23 



33.90 



47.45 



2.86 



16.04 



.00 



.00 



.00 



51.61 



1.87 



4 59 



31.64 



5.99 



29.90 





9.65 



Do... 





1.65 



Do 





5.02 





.00 



Do... 



.00 



Do 



.00 





7.01 





.13 



Do 



.00 



Do. . 



2.71 





3.83 



Do.. 





15.39 









Total 



2, 567. 46 



191. 95 





45.39 









i These plots did not contain the same number of plants, so that a direct comparison of yields between 

 the different plots can not be made. 



Plants without rootstocks like those here studied are either killed 

 or much weakened when the herbage is cropped 1 inch above the 

 ground at monthly intervals. More frequent cropping has even 

 more disastrous effects. Mountain brome, one of the most valuable 

 forage plants in the aspen-fir and spruce-fir types and a rapid-grow- 

 ing and heavy-yielding plant under favorable conditions, was 

 killed by the fourth and fifth harvestings in the first year. Wild 

 geranium, also, is seriously affected by close, repeated cropping, for 

 its leafage develops uniformly throughout its area, and when it 

 is defoliated, as by grazing, leaf expansion must originate from 

 the unfolding of new buds. A method of grazing which removes 

 most of the herbage at monthly intervals, four or more times in a 

 season, the first harvesting being two weeks after growth begins, 

 results in the killing out of many plants and the serious impairment 

 of the vigor of the others. 



The closeness of the cropping during the growing season appears 

 to have much influence on the yield and longevity of the vegetation 

 when the plants are harvested frequently. A plot of Letterman 

 needle grass harvested with the same frequency as those heretofore 

 mentioned, but cut at a height of not less than 2% inches above the 

 ground, had at the end of three years' treatment practically re- 

 tained its initial vigor and yield. The yields on this plot, con- 

 secutively, for the three years of treatment, were 29.35, 19.32, and 

 23.68 grams. 



COMPARATIVE EFFECT OF DIFFERENT FREQUENCIES OF HARVESTING 



The results on plots harvested twice and on those harvested five 

 times in a season for three successive years are given in Table 6 9 

 and Figure 11. The plots harvested twice were cropped just be- 

 fore seed maturity and again at the close of the growing season; 

 those treated five times were cropped two weeks after growth began, 



9 The data presented here for plots harvested five times are essentially a repetition of 

 those given in Table 5, but in this case a selection was made in order to compare plots 

 having the same number of plants of the same species and occurring in the same zone. 



