390 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Forest cxpoiimcnt stations. To the Coconino Station, previously 

 established in District 3, there were addetl last year two new stations, 

 the Fremont and the Wagon Wheel Gap. The Fremont Station, 

 named in honor of Gen. John C. Fremont, is located about 4 miles 

 from Pikes Peak, at about 8,850 feet elevation. The Forest ranoje is 

 here between 6,500 and 11,500 feet, and either extreme is within 4 

 miles of the station. A small nursery has been established to supply 

 material for planting experiments. Such experiments were made 

 with white pine, Scotch pine, and sugar maple on cool, moist 

 situations, and with various other species. Collections including 

 systematic and type herbaria, soil ancl rock, wood-destroying fungi, 

 insects, rodents, etc., have been started. 



The factors determining the occurrence of the various types in 

 this region will be accurately determined. A study to determine 

 the character and value of the factors which distinguish the yellow 

 pine and Engelmann spruce types at an elevation of 8,900 feet and 

 to measure those climatic and soil factors wliich determine growth, 

 flowering, and seed bearing and those which may cause a pathological 

 condition is under way. In cooperation with the Weather Bureau 

 meteorological observations are carried on at the experiment stations. 

 The necessary instruments have been loaned the Forest Service by 

 the Weather Bureau. Accurate measurements on self-recording in- 

 struments of all weather factors are recorded, the measurements being 

 taken on various slopes and aspects. 



At the Coconino Experiment Station in Arizona the investigation 

 of climatic conditions in an open park and surrounding timbered 

 areas begun January 1, 1909, was continued. The results have an 

 important bearing on the difficult problem of reproduction in the 

 Southwest. They indicate that the forest exerts a very marked 

 ameliorating influence upon extreme temperatures, wind movement, 

 and evaporation. The most striking difierence between forest and 

 park conditions is in the minimum temperature, which on cold, clear 

 nights was found to be as much as 23° F. lower in the park than in 

 the forest. The enormous disparity between the park and forest 

 temperatures has led to the suggestion that the difference may be 

 mainly one of air drainage from the San Francisco peaks, the base of 

 which lies within 4 miles of the station. In order to decide this, it 

 will be necessary to carry on simflar investigations in a locality 

 removed from the immediate influence of high mountains. 



At the same station considerable progress was made in experiments 

 to determine b}^ actual measurements the light requirements of 

 species. These experiments are complicated by the influence of 

 other factors on the growth of trees, which must be separated from 

 the influence of light. To measure the variations of light rec[uire- 

 ment of the species it is necessary, first, to measure the light inten- 

 sity in which it is found; second, to take observations on the response 

 of plants in different light intensities; and, third, to measure as far 

 as possible the other factors influencing growth, such as the tem- 

 perature and humidity of the air and the temperature, moisture con- 

 ditions, and quality of the soil. 



Two permanent sample plots were established in 1909 in the west- 

 em yellow-pine type of forest to secure light measurements and 

 observe the development of seedlings from year to year. On each 

 of these plots several light-measuring stations were selected in groups 



