BANGE MANAGEMENT IN NEW MEXICO. 21 



dry and windy as to dry up or cut off the young seedlings. In an 

 experience extending over about twenty years but three such springs 

 occurred at one point in the region mentioned. In the summer after 

 the rains there is commonly an abundant crop of such plants. 



Many of these plains are really bolsons, or basins, without a drainage 

 outlet, and in all such low places where the water collects and evapo- 

 rates, as well as in many places in the river valleys where the water 

 table is near the surface, alkali occurs in greater or less abundance. 

 In such places may be found an association of alkali-loving plants, 

 many of which are usable as forage in default of something better. 



Porous gravelly mesas. — In the southern part of the State are large 

 bodies of dry, porous, gravelly soil that usually lie as bands of greater 

 or less width paralleling the mountain chains. The dominant plants 

 of these areas are shrubs of no forage value, and there are few forage 

 plants of any kind in the association. The factor which in the last 

 analysis determines the distribution of this association is probably 

 one of soil aeration, though it may be dependent upon the amount of 

 available water. 1 



Where wind-transported sand or loess collects under the protection 

 of bushes, bluffs, or other obstructions, a spot of soil of an entirely 

 different texture is formed and other plants occur. It is not uncom- 

 mon to find in these bush-covered areas spots of this kind, from a 

 few square feet to several acres in extent, upon which occurs an almost 

 pure stand of grass. (PL V, fig. 2.) 



Sometimes there is a good crop of annuals upon these gravelly 

 mesas, but this crop is rarely used, since at such times there is an 

 abundance of better feed elsewhere. These areas also are poorly 

 supplied with watering places, because the feed will not warrant the 

 expense. If some drought-resistant shrub having a value as forage 

 could be found that might replace the valueless shrubs of these areas, 

 much land now useless could be rendered productive, at least to some 

 degree. The amount of vegetation now produced upon these areas 

 is about the same as that upon the tight soils of the region, but it is 

 not usable because of its kind. Hence, there is hope that a valuable 

 plant may be found that will grow here. 



Arroyos. — In most general terms, the plants that grow in the arroyos 

 or dry watercourses are the same that grow in the foothills of the 

 near-by mountains and have followed the drainage channel down- 

 ward, or those that have followed back up these channels from the 



1 An Investigation carried on at the New Mexico Agricultural College by a s tudent assistant of the writer, 

 Mr. O. B. Metcalfe, demonstrated pretty completely that a pronounced tension line between almost pure 

 creosote-bush and shadscale associations was not due (as we had long believed) to a difference in alkalinity 

 of the soils. Careful examination, chemically and physically, of the soils to a depth of 6 feet at several 

 places across the tension line showed no differences in soil except those arising from the size of the particles. 

 The soil upon which the creosote-bush association grew was very gravelly, and some of the bowlders con- 

 tained in it were so large that it was necessary several times to dig a pit instead of using the soil auger to 

 get the soil samples. The soil supporting the shadscale association was much more finely grained, being 

 mostly a sandy loam at the surface and not gravelly below. 



