FOREST SERVICE. 393 



the Rio Grande at a point about 1 mile above Wagon Wheel Gap. 

 The head of each stream is at an elevation of about 10,500 feet and 

 the mouth at an elevation of 8,700 feet; the length of each stream is 

 approximately 1 mile. A concrete dam and settling basin have been 

 built in each stream at an elevation of about 9,500 feet, and each is 

 equipped with an automatic river-stage register recording the height 

 of the stream over a weir. Accurate measurements of the precipita- 

 tion at various points on each watershed will be recorded and other 

 meteorological observations taken. Both watersheds are now almost 

 completely forested, with good cover conditions. During the first 

 two years of the experiment the flow of the two streams will be con- 

 tinually measured with the cover conditions as they are now. During 

 both this and the succeeding period all climatic factors which may in 

 any way help to explain the behavior of each stream at stated times 

 will be measured. The fall, melting, and evaporation of snow will also 

 be carefully studied. After two years, the relative character and 

 amount of flow from the two watersheds having been learned, one of 

 the watersheds will be entirely denuded of forest cover, and also burned 

 over. The behavior of the streams under these conditions will be 

 studied during the period of denudation, formation of sod, period of 

 overgrazing, and perhaps during reversion to forest. 



OTHER STUDIES. 



Experiments have also been carried on in thinnings in order to 

 determine the increased rate of growth and whether a better quality 

 of timber is produced. Plots 50 by 100 feet have been laid out on a 

 steep south slope with good sandy loam soil in the Black Hills National 

 Forest. The plots were thinned to a spacing of about 5-J, 3|, and 4| 

 feet, respectively. All the remaining trees were numbered and 

 measured for actual height to the nearest foot and diameter to the 

 nearest tenth of an inch. Future measurements at intervals of about 

 five years will determine the rate of growth. Similar experiments 

 have been started in lodgepole pine, Engelmann spiiice, and balsam 

 fir, and on other Forests. 



The beginning made in 1909 and the year before in reconnaissance 

 studies on National Forests was carried forward more extensively. 

 These timber estimates and studies are made for the purpose of 

 ascertaining the resources of the Forests and are used as a basis for 

 outlining a plan for their future management. The data gathered 

 cover chiefly the amount, quality, character, and location of standing 

 timber, the rate of growth of the dilferent species, the most desirable 

 location for sales, and the logging methods which should be used. 

 Bodies of timber which should be removed for the good of the Forest 

 are located and recommendations made for their sale. Fire-killed 

 areas and insect infestations and other causes of injury to the Forest 

 are noted. Wlien the work is completed for any Forest there are on 

 hand reliable estimates of the timuer by sections, defmitely formu- 

 lated knowledge as to where, at what price, under what logging 

 methods, and imder what restrictions timoer can be advantageously 

 sold, timber maps, and in general full details needed for careful and 

 intelligent management . 



In addition to the reconnaissance mentioned in last year's report, 

 which involved the cruising of over 2,000,000 acres of timberland, 



