VOLUME XLIV 



NUMBER 5 



Botanical Gazette 



NOVEMBER igoj 



THE FOREST FORMATIONS OF BOULDER COUNTY, 



COLORADO 



Robert T. Young 



: (with twelve riGURES) 



The present paper purposes to describe the forest formations 

 of the eastern slope of the Rocky Mountains in Boulder County, 

 Colorado. There has been a larg^e amount of work done on the flora 



of Colorado from the systematic and distributional standpoint, the 

 results of which are contained in Rydbei^g's Flora oj Colorado 

 (Bull, loo, Colorado Agricultural College Experiment Station, 1906)* 

 In the publications of the Forestry Bureau, U. S. Department of 

 Agriculture, and the U. S. Geological Survey, there are a few papers 

 treating of the economy (and incidentally the ecology) of the forests 

 of the state; while a popular paper by Ramaley (''Remarks on the 

 distribution of plants in Colorado east of the divide") appeared in 

 Postelsia for 1901, in which is given a considerable mass of data on 

 the distribution and ecology of the plants of this region; but as yet 

 there has been done no work of an exact character in the determination 

 of the physical conditions under which the forests exist. For this 

 reason I hope that the following discussion will prove of value* 



The discussion will cover the following points: introduction, 

 being a brief account of methods employed and a short description 

 of the physical features of the region studied; composition of the 

 forests with reference to the controlling and most common secondary 

 species, and the relationship between them; physical character of 

 the habitat with reference to water content of the soil, temperature 

 of air and soil, humidity, light, pressure (altitude), slope, and expo- 



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