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6 BULLETIN 1227, U. S. DEPARTMENT OF AGRICULTURE 
Changes in the vegetation were measured quantitatively by means 
of five permanent quadrats, two in each of the fenced areas and 
one outside. These were charted every year at the end of the grow- 
ing season and one quadrat in each of the three plots clipped at that 
time and the crop of grass weighed by species. The results thus 
measured were striking, and show in a very marked manner not only 
the differential effects of rodent and cattle grazing, but the responses 
of each of the grasses to such grazing (Pls. V and VI). 
In 1918, when the first three quadrats were installed, the sand drop- 
seed (Sporobolus cryptandrus) was almost extinct, appearing in 
only one of them. This was due largely to its great palatability, 
both cattle and prairie dogs seeking it and grazing it to the ground 
at alltimes. The established plants were holding on in some measure 
by producing a crop of short leaves close to the ground in the man- 
ner characteristic of the blue grama, which enabled them to survive 
in spite of close grazing by cattle. But plants near the prairie-dog 
burrows were utterly destroyed, for the rodents had grazed the 
grass down to the tops of the roots, rarely leaving so much as a bud 
to reestablish the plant. 
The chief result noted after the growing season of 1918 was the 
first appearance of seeding plants of dropseed in the totally pro- 
tected plot. Such plants occurred in the prairie-dog inclosure also 
but only at some distance from the group of burrows. Very few of 
these plants were seedlings; in fact, nearly all may be said to have 
been established plants, permitted by protection to produce their first 
real crop of seed. 
As a result of this crop, the fall of 1919 showed dropseed plants 
everywhere on the whole area, and from that time on this grass has 
been of almost equal importance with wheat grass on and around the 
plots. This was due to the great amount of seed produced in the 
protected plots scattering over the entire area and reestablishing 
plants where grazed out. The plants were grazed down by cattle 
outside the plots, however, and in the rodent inclosure, were grazed 
down and gradually killed so that while these plots showed at times 
nearly as many plants per square meter as in the protected area, 
clipping in fall showed lttle forage left. 
In the spring of 1918 the wheat grass (Agropyron smithii) 
plainly showed the effects of overgrazing. This grass does not 
produce short leaves close to the ground as does blue grama (and 
also dropseed when forced to it), but sends up leafy stems which, 
when grazed closely, have no photosynthetic surfaces left. Such 
plants must draw upon stored food-material to send up short shoots 
which may escape and permit food supplies to be in some measure 
replenished. The habit of the wheat grass of spreading by rhizomes, 
however, is distinctly in its favor. Saude is always a precarious 
means of reproduction under grazing conditions, while spreading 
by rhizomes permits pooling of the food produced by the few 
shoots which escape for the use of all shoots arising from the 
rhizome. The tougher texture and scabrous leaves of the wheat 
grass make it less palatable than either grama or dropseed, hence 
a few shoots at least are apt to remain untouched. When heavily 
grazed for some years, however, the rhizomes become starved, and 
RE eta a 
