MIXED GRASS AND WEED STAGE iii 



wheatgrass, is soon killed out. On the bunch wheatgrass lands 

 the invading yellowbrush and porcupinegrass are relatively 

 persistent. 



Forage Production. — The wheatgrass cover produces a large 

 amount of forage which is especially well suited to the grazing 

 of cattle and horses. Sheep and goats, however, make better 

 returns on a mixed grass and broad-leaved herb cover, preferably 

 where broadleaves predominate, than on a pure grass type. This 

 statement, however, should not be interpreted to imply that on a 

 highly developed grass cover overgrazing by sheep or goats is 

 justified in order to increase the stand of broad-leaved plants. 

 Such destructive cropping will seriously decrease the forage pro- 

 duction of the land for the grazing of cattle and horses. After 

 a few years of full utilization of the wheatgrass cover by cattle 

 and horses, a considerable variety of plants usually appears, 

 thereby increasing the value of the type for the grazing of sheep 

 and goats. 



MIXED GRASS AND WEED STAGE 



This vegetative stage, next to the wheatgrass type, con- 

 stitutes the highest and most stable cover. As indicated, where 

 the wheatgrass cover is destroyed gradually, but where the fer- 

 tihty of the soil and its plant water content are not greatly 

 decreased, porcupinegrass and yellowbrush (Fig. 31) soon gain 

 dominion of the area, and hence signify the waning of the wheat- 

 grass cover. As a great variety of both deep-rooted and shal- 

 low-rooted plants makes up the vegetation of the porcupine- 

 grass-yellowbrush type, it is popularly referred to as the " mixed 

 grass and weed " stage. The highest development of this type 

 is indicated by at least a scattered stand of wheatgrasses. A 

 well-established porcupinegrass-yellowbrush cover usually also 

 supports a goodly sprinkling of bluegrasses {Poa) and some 

 fescuegrasses (Festuca). The gradual depletion of this vege- 

 tational stage is usually indicated by the invasion and establish- 

 ment of bromegrasses (Bromus), not uncommonly by an in- 

 creasing abundance of fescuegrasses, and several species of per- 

 ennial broad-leaved herbs. Among these, foxgloves, notably 



