1907] YOUNG— FOREST FORMATIONS OF COLORADO ^t,^ 



Owing to the physical condition of the surrounding habitats, the 

 Populus occidentalis-Salix fluviatilis formation is in a practically static 

 condition. My data on the physical characters of the habitat of this 

 formation are as follows : " 



Observations taken on Boulder Creek east of Boulder during 

 July 1905 gave results as follows: 



+ 



Temperatures^ 



(Observations July 3, 11 A. m.; 10, 10:45 A. m.*, 24, 11:15 A. M.; 28, 1:45 p. m.) 



Minima i6?2 i6° i6?6 2o?5 2i?2 



Maxima 2o?25 i8?s 3i?25 26^5 25^5 



* Zero indicates the ground surface, minus readings below surface, and plus readings above the 

 surface. 



Water content 



Observations 1 1 . 25*=" 22 . 5— 1 1 . 25^" 



July 10 30 . 1 per cent. 18 . 3 per cent. 



July 24 8.8 per cent. 9 per cent. 



h 



Relative humidity 



(Observations July 3, It A. &f.; 10,10:45 A.M.; 24,11:15 A.M.; 38,1:45 P.M.) 



Am 



1*S 



cm 



9 



Minima 43 per cent. 3^ P^^ ^^^t- 



Maxima 73 pc^ cent. 60 per cent. 



The light value in this formation taken above the under layer at 

 noon on August 7 was 9 : 180. 

 \ In a thicket of Corylus rostrata at the mouth of Boulder Canon, 



three series of observations gave the following results : 



4 



Temperatures 



(Observations June 24, 10:15 .\. M.; July 17, 12:20 p. u,\ August 301 7 a. m.) 



Minima i3?5 i3?8 i4?4 i6?75 if i7-5 



Maxima i8° i8^ 2i?5 25?$ 27° 27-5 



Water content 



Observations 1 1 . 75^* 22 . 5 - " i - 25*"* 



June 24 29 . 5 per cent. 24 . 6 per cent. 



July 17 12.5 per cent. 12.4 percent. 



Aug. 30 5.3 per cent. 7-2 per cent. 



Relative humidity 



(Observations June 24, 10:15 a. m.; July 17, 12:20 P. M.; August 3o» 7 a. m.) 



Minima 30 per cent. 27 per cent. 26 per cent. 



Maxima 80 per cent. St, per cent. 88 per cent. 



