32 BULLETIN" 1031, U. S. DEPAETMEXT OF AGRICULTURE. 



understocking with some loss of forage, or overstocking and conse- 

 quent injury to the range. Although it would be far better and 

 cause less loss of forage in the long run to understock slightly each 

 year, the tendency in the past has been toward overstocking. Until 

 the proper rate of stocking has been determined, however, careful 

 observation of range and stock should make possible the detection 

 of deterioration in time to provide for recuperation in a few seasons. 



Overgrazing on grama-grass range in the Southwest may be recog- 

 nized to some extent in its first year by observations of the degree 

 of cropping of the grass. Ordinarily grama grass should not be 

 cropped closer in any year than will leave the lower joints of a few 

 grass stalks on each tuft. This will provide a means of revegetation 

 under favorable conditions the next year. 



Black grama grass reproduces mainly by stolons. A number of 

 the mature flower-stalks of each plant bend to the ground, sending 

 forth a crown of leaves at each node or "joint" which takes root 

 when it strikes the soil. Eventually as the little plants become es- 

 tablished the connecting part dies and an independent plant is thus 

 formed. If the grass is grazed so closely that no nodes are left 

 there is no opportunity to revegetate by this method. 



In loose soil overstocking results in the trampling and loosening 

 of the surface soil so that the roots of the grasses are exposed and 

 wind erosion begins. If the stock grazing an area fall off in con- 

 dition faster than other causes warrant, overstocking is no doubt 

 occurring. 



Following the first year of overgrazing unpalatable annual grasses 

 and weeds and short-lived perennial plants usually increase along 

 with a reduction in number of leaves and height of the grass and in 

 the number of flowering stalks and stolons. These secondary species 

 increase with continued overgrazing and deterioration of the range 

 until they are the only vegetation present. This is the case within a 

 radius of one-half mile around some stock-watering places in the 

 Southwest. The main plants indicating the first stages of deteriora- 

 tion in the grama-grass range of southern New Mexico are such 

 annuals and short-liv\ed -perennial plants as tall eriogonum, sixweeeks 

 grasses, spectacle-pod, whitestem, and yellow caltrops. 



The best indicators of later stages of deterioration are dropseed 

 grasses, leatherweed, silvery nightshade, and yellowhush, followed 

 b}' snakeweed, and finally the mesquite-sandhill type if overgrazing 

 and wind erosion is allowed to continue too long. 



Where overgrazing has reached the stage where mesquite sandhills 

 are being formed it will be difficult to restore the range. Effort 

 should be made to detect the breaking down of the range much 

 earlier, or as soon as the annuals and short-lived perennials begin 

 to increase and the good grasses to decrease. Figures 1 and 2, 



