442 A NATIONAL PLAN FOR AMERICAN FORESTRY 



the ponderosa pine area at the head of Senorita Canyon near Cuba, 

 N.Mex., on which as lately as 20 years ago low vegetation was rather 

 scanty and erosion was very active, as a result of grazing regulation 

 the slopes are now well carpeted with bunch grasses, sheet erosion 

 is practically stopped, and the cutting in gullies is checked. Sides 

 of gullies formerly 1 to 3 feet deep have assumed an angle of repose 

 and the grasses that have come in on them have stabilized the soil. 



On many private commercial timberlands, timber cutting and 

 grazing have been, and are continuing to be, severe. The vast 

 timbered area at the headwaters of the Chama River comprised by 

 the old Tierra Amarilla Grant, for example, has been cut over within 

 the last 40 to 50 years, and this cutting has been followed by severe 

 grazing. As a result much of the area formerly forested is now brush 

 land or low-density grassland. Observations by members of the 

 Forest Service extending over the last 20 years indicate that these 

 changes have been followed by an intensification of floods, increased 

 bank cutting, and an increase in the silt burden of flood waters in 

 the Chama River. Some of the once fertile irrigated farm lands on 

 the river have become silt-sand wastes. 



Interspersed with the timber types, a rather dense chaparral type 

 occurs largely on high mountain slopes. The brush consists principal- 

 ly of scrub oak, New Mexican locust, and aspen, with an undercover 

 of grasses and other herbs. This type affords a high degree of water- 

 shed protection. Fire is very injurious to it and the destructive 

 grazing, also, has greatly impaired its protective value. 



Above the commercial spruce stands is the subalpine forest type, 

 consisting of scattered patches of spruce and fir interspersed with 

 grassland or brush areas. Few of these small patches of timber have 

 been depleted. With their rather dense growth, large quantity of 

 litter, and herbaceous and shrubby vegetation they control erosion 

 and reduce surface run-off from snow and rain to an almost negligible 

 quantity. The grasslands intermixed with these timber clumps 

 furnish a very effective watershed cover unless depleted. Being 

 naturally good forage, before the creation of the national forests 

 they were subjected to severe overgrazing which thinned the grasses 

 and often caused them to be replaced by a scant stand of w^eeds of 

 far less value in controlling run-off and erosion. The rather deep 

 soil common on grassland areas of the subalpine type has been rather 

 severely eroded. This erosion has not yet been entirely controlled, 

 although on most of the eroded areas a protective grass cover is 

 being restored. The rapid run-off made possible in part by the 

 system of gullies in this grassland type, and the eroded material carried 

 by this run-off, have tended to cause continuance of active cutting 

 of stream banks in timber areas below. 



Of the 17,460,000 acres of forested land in the Rio Grande Basin, 

 14,168,000 acres has been classified as of major influence and 3,292,000 

 acres as of moderate influence in watershed protection. (See figs. 6 

 and 12.) 



LAND MANAGEMENT AS AFFECTING WATERSHED PROTECTION 



Measures necessary to correct unsatisfactory erosion and run-off 

 conditions at the source, on the slopes of the watershed, include 

 eliminating destructive grazing and timber cutting, controlling fires, 



