RANGE AND CATTLE MANAGEMENT DURING DROUGHT. 9 
erass type. The grama grass occupies the more compact sandy soils, 
and this phase of the mixed-grass type the slightly looser soils. 
The snakeweed type, although of minor importance, resembles the 
erama-grass and mixed-grass types in composition of forage plants, 
with the difference that snakeweed is the predominating species. 
There are also more weed species in this type, probably because the 
soil is a little looser than in the two types just discussed. Snake- 
weed is often an indicator of overgrazing, especially when it comes 
in on areas of better soil, but it also occupies a natural habitat of its 
own on the loose soils. 
The mesquite-sandhill type has a very low density of palatable 
vegetation. It occupies more area than any other type on the plains 
areas of the reserve. Mesquite is the predominating plant species in 
the type, occurring in clumps which serve to catch blowing sand and 
thus to form the mounds or small sandhills. Other browse species 
occurring with the mesquite are shadscale and sagebrush, the sage- 
brush sometimes predominating on small areas to an extent that a 
distinct sagebrush type is formed. Both these species of brush are 
good forage for cattle, especially in winter. Grama grass, red three- 
awn, and dropseed grasses are the most important grasses found here, 
and, although they ordinarily occur sparsely, furnish the bulk of the 
feed in the type. A scattered stand of soapweed is characteristic of 
this type. Drifting of the soil occurs during high winds, and this 
makes it difficult for vegetation to become established from seed. 
In all four of these types black grama grass is the most important 
forage species. The three-awn grasses and the various browse spe- 
cles are next in importance. These grasses are good forage when 
they are green, and they cure on the stalk on the range. The dry for- 
age is readily eaten by stock. The various browse species in the 
mesquite type are grazed mainly during winter and spring. Conse- 
quently the grama-grass type and the other types in which grama 
grass or browse are the predominating forage species are important 
for winter and spring grazing, when there is little new growth, and 
the demand upon them for these seasons should be given first consid- 
eration. Also, since grama grass is the principal forage species in 
all of these types, their management should be based upon the 
growth requirements of grama grass. 
SUMMER RANGE TYPES. 
The swag or swale type (PI. I, fig. 2) occurs on the low flat places 
of tight soils that are flooded from run-off in time of rains. ‘Tobosa 
grass and burro grass are the only species of importance in this type. 
Bordering on the swag type and on somewhat similar situations is 
a mixed-grass type in which occur mainly tobosa grass, burro grass, 
and saltgrass (given in the order of their importance). 
