INCREASE OF SHRUBS. 21 



proportion to the production of only 14 pounds on 2.64 inches in 

 1904. As a matter of fact nearly 2 inches of the rainfall which pro- 

 duced the spring crop of 1904 fell in the months of October to De- 

 cember. This served to germinate the seed very well, but there 

 was not moisture enough in the spring to make any considerable 

 growth. This is a good illustration of the influence of proper dis- 

 tribution of moisture as well as proper quantity. 



CARRYING CAPACITY. 



As stated elsewhere, the large field has not yet been pastured, the 

 object thus far being to study recuperation under absolute protection. 

 The only data secured on carrying capacity are from the pastures 

 under private cooperative control contiguous to the upper side of 

 this field. The most satisfactory record, all things considered, is 

 from the "MacB." pasture. (See PL V, fig. 1.) The record is short, 

 but even the first year after being inclosed the land improved very 

 perceptibly and still maintained stock at the rate of one head to 20 

 acres. It should be stated that this pasture is about one-fourth in 

 the oak belt and the remainder in the open grass land immediately 

 below. It is probably the best pasture land in this region. The 

 204-acre pasture is smaller and less productive by far, mainly on 

 account of thick brush. A long record, reaching over five years, is 

 available for this pasture. Four burros and three horses run short 

 of feed in this pasture occasionally. Of course, the brush interferes 

 with the growth of grass somewhat. On the other hand, the mesquite 

 (Prosopis velutina) furnishes some beans, which are a valuable for- 

 age. Pasture experiments in the large inclosure were begun in the 

 summer of 1909, and the results will be reported later. 



INCREASE OF SHRUBS. 



Much has been written about the rapid spread of the mesquite 

 (Prosopis (jlandulosa) and other shrubby vegetation in Texas since 

 the advent of flocks and herds, but the development of this class of 

 plants is so much slower on the inclosed area referred to in this paper 

 that it appears to have been in a large measure overlooked. It is, 

 however, taking place just as surely as in Texas; the only difference 

 is that the growth is much less than half as rapid. 



The year previous to the inclosure of the large field a small crop of 

 hay was cut over the best portion of its present area. This, however, 

 was far from any water. Acres were harvested where there was no 

 impediment to the mower. At the present time, six years later, 

 there is not an acre in the whole field where there are no shrubs to 

 interfere with the machine. They are still small, half an inch to an 

 inch in diameter at the base, but large enough to stop a mower. 



177 



