FORESTS AND STREAMFLOW 407 



give any immediate results — they can only be satisfactory when pursued with 

 great care for a term of years. Briefly the plan is to compare two watersheds 

 adjacent to each other on which practically the same conditions exist, one 

 being forest covered and the other denuded. Mr. Bates describes the two 

 watersheds as follows : 



"The two watersheds at the Wagon Wheel Gap Experiment Station are 

 very much alike with respect to topography, soil, and vegetation cover. A 

 good deal of difiBculty was encountered in finding two such similar areas 

 at an altitude which represents a mean between the heavily-watered mountain 

 tops and the low-lying areas where the streams are not permanent. The area 

 of Watershed A is 223 acres and of Watershed B 212 acres. The former has 

 a total length of 7,100 feet and a maximum width of 1,800 feet. The latter 

 has a length of 4,600 feet and a maximum width of 2,500 feet. It may thus be 

 seen that Watershed A is longer and narrower than Watershed B. The 

 visible lengths of the two streams are 3,400 and 2,300 feet, respectively. Both 

 streams have an easterly bearing, flowing out of the mountains on to the 

 broad bottom of the Rio Grande, where, excepting at the highest stage, they 

 disappear in the loose soil of the river bottom. 



"The altitude of Watershed A is from 9.375 to 11,360 feet, while Watershed 

 B lies between the elevations of 9,240 and 10,940 feet. At these elevations 

 precipitation is suflicient to feed permanent streams. I think it is safe to 

 say that the streams in question have never gone dry, since the season of 1910 

 represents an almost unprecedented drought in this locality and the streams 

 at the end of the summer showed discharges of .075 cubic feet per second 

 and .050 cubic feet per second, respectively, or about 20 per cent of the annual 

 mean discharge. 



"In each case the forest cover consists of Douglas fir in the lower reaches 

 and Engelmann spruce at the higher altitudes. Douglas fir on north slopes 

 is representative of the Rocky Mountain form of this tree. On south slopes 

 it forms an open stand of fairly thrifty and commercially valuable trees, the 

 litter in most cases covering the ground only in the immediate vicinity of 

 the trees. On north slopes the Douglas fir becomes more and more supple- 

 mented by Engelmann spruce as one proceeds upward. At the heads of the 

 watersheds the Engelmann spruce stands have been considerably damaged by 

 fire, followed by the replacement in some cases of Engelmann spruce, but more 

 generally by stands of aspen in which the forest floor conditions are quite good. 



"Douglas fir and Engelmann spruce undamaged by fire occupy about 40 

 per cent of the area of each watershed. In Watershed A the remainder is 

 made up of aspen, under most of which there is good reproduction of coniferous 

 species, and a small area of bristlecone pine. The balance in Watershed B 

 is made uj) almost wholly of aspen in which there is a smaller proportion of 

 good reproduction. 



"Both watersheds have been partially burned, the most recent burns being 

 about 17 years old, the earliest as much as 50 years. The only burn not 

 restocking is at the head of Watershed A and represents about 2 per cent 

 of the area of that watershed. Steps have already been taken to obtain a 

 stand of Engelmann spruce on part of this area, by seed-spot sowing, and 

 similar work has been done in the more ojien areas of Douglas fir on Water- 

 shed A. Wliile the effect of this planting, within the period of the experi- 

 ment, can be but slight, yet any improvement of the forest cover of Watershed 

 A occurring simultaneously with the deforestation of Watershed B must 

 accentuate the desired contrast. 



"As a whole, the forest-cover conditions on both watersheds are fairly 

 representative of conditions thi-ouglmut the Rocky Mountain region which 



