28 



CIRCULAR 



U. S. DEPARTMENT OF AGRICULTURE 



Table 5. — Density and composition of vegetation on grazed plot of 

 meadow B, by value 1 as forage for sheep, in specified years 1940— t8 2 





High value 



Moderate value 



Low value 



Year 



Den- 

 sity 3 



Percent of 

 composition 



Den- 

 sity 3 



Percent of 

 composition 



Den- 

 sity 3 



Percent of 

 composition 



1940. . 



6.94 

 14.42 



25.38 



39 

 60 



82 



1.56 



1.80 

 1.32 

 1.81 

 .83 

 1.72 



9 

 7 

 4 

 5 

 4 

 5 



9.47 

 8.06 

 4.27 

 5.27 

 2.03 

 5.53 



52 



1943 



33 



1945 



14 



1946 



26.45 79 

 18.94 87 

 25.59 78 



16 



1947. . . 



9 



1948 



17 











1 High value: Species that ordinarily would have 40 percent or more of their 

 herbage removed when meadow is properly grazed. 



Moderate value: Species that ordinarily would have 20 to 39 percent of their 

 herbage removed when meadow is properly grazed. 



Lore value: Species that ordinarily would have less than 20 percent of their herbage 

 removed, or remain ungrazed. when a meadow is properly grazed. 



2 Pocket gophers were removed from meadow in fall of 1940. 



3 Square feet per hundred of ground cover. 



value, they have a rather restricted period of use. Further improvement 

 in the meadow would have been through replacement of the succulent 

 weeds with slower maturing grasses that remain green longer. Such a 

 condition existed on meadow A, which was further along in range 

 improvement as a result of gopher control from 1931 to 1940. 



The 1947 grazing capacities on meadow A were 2.41 sheep months per 

 acre on the grazed plot and 4.62 sheep months on the ungrazed plot. 

 This represents about a 7-percent reduction (grazed plot) and 32-percent 

 increase (ungrazed plot) in the grazing capacities of the two plots prior 

 to the introduction of gophers in 1940. During 1948, because of the 

 greater vegetative growth, grazing capacities of both plots were much 

 higher. 



The relationship between the presence of pocket gophers and changes 

 in forage value of meadow vegetation in fair condition may be studied 

 by comparing the proportion of plants of low, medium, and high forage 

 value on the grazed plot of meadow A (table 6). As is to be expected on 

 a mountain meadow, the actual and relative amount of vegetation in 

 each forage-value class fluctuated from year to year. This was due in 

 part to differences in growing conditions. However, from 1940 to 1948 

 no adverse trend in forage value resulted from the introduction of the 

 pocket gophers, except possibly immediately after the introduction and 

 in the dry year of 1947. 



Forage values were reduced somewhat during the first 3 years after the 

 gophers were introduced; the density of species of high and moderate 

 value decreased markedly, while species of low value increased. This 

 accounts for the drop in grazing capacity between 1940 and 1943. How- 

 ever, in the years following 1943 there was a gradual trend toward an 

 increase in the combined amounts of species of high and moderate 

 forage value and a decrease in species of low forage value. By 1948 the 

 density of both high- and moderate-value species exceeded their 1940 

 densities, and the density of low-value species was about a third lower. 



Results of the effect of pocket gophers on grazing values of meadows 

 A and B, together with the life history studies of the gopher, suggest 



