ADMINISTRATION 91 



the effect of cutting timber upon the climate within 

 the forest. 



Meteorological Observations. The climatic re- 

 quirements of forest types have been studied at the 

 Fremont Experiment Station since January 1, 

 1910, through experimental observations, and other 

 stations have taken up the same problem since that 

 date. The first step in this work at the Fremont 

 has been to obtain a complete meteorological rec- 

 ord as a basis for determining what climatic condi- 

 tions are most important in limiting the natural 

 range of such important species as Yellow pine, 

 Douglas fir, and Engelmann spruce. The data 

 collected so far have shown that soil moisture and 

 soil temperature are the controlling factors in de- 

 termining the existence of the three forest types. 

 It has also been shown what climatic conditions 

 each of the three types of forest must have in order 

 to succeed. This work has since been extended to 

 include other types of forest and a meteorological 

 station has been established at timber line on Pikes 

 Peak. This station, which is at approximately 

 11,500 feet, is equipped with self-recording instru- 

 ments to measure the climatic factors which obtain 

 at that elevation and which mark the uppermost 



