THE MONTANE ZONE 143 



on green trees, but this is relatively rare. There is at hand a 

 branch about a foot in length bearing 27 cones, about evenly dis- 

 tributed over a period of 12 years, and not one of them has be- 

 gun to open. Of 167 cones collected in August five years ago 

 and kept continuously in the dry air of the laboratory, 70 still 

 show no signs of opening, 14 are beginning to open, and 83 have 

 opened enough to liberate a few over 200 seeds in all. These 

 seeds when tested showed a high pereentage viable. 



Lodgepole pine is not abundant in the immediate vicinity 

 of Missoula. It is restricted mostly to north slopes at elevations 

 of about 5,000 feet. This feature of its distribution seems to 

 be mainly a response to temperature. Lower elevations though 

 well watered rarely support vigorous stands in this locality, but 

 farther north in the CJlncier Park at 4,200 feet, and in the 

 Kootenai Valley at less than 2,000, are vigorous forests of pure 

 lodgepole. In these regions heavy frosts may occur in any 

 month of the year. Northward the lodgepole forests become 

 more continuous and homogeneous; southward the continuous 

 and extensive forests of this species are found at seccessively 

 higher altitudes. 'Westward, of course, the lodgepole extends to 

 the coast ; its eastward distribution in Montana reaches a merid- 

 ian traversing the State midway. In the north it is found in 

 the Bearpaw Mountains, a low range between the Milk River 

 and the Missouri south of Havre. It occurs also in the Crkzy 

 Mountains almost in the exact center of the State and in the 

 Beartooth Mountains northeast of the Yellowstone Park. In 

 this region Leiberg, reckoning trees of all ages with a basal 

 diameter of three inches and upward, concluded that the lodge- 

 pole constituted 45% of the forest species, and in the Little Belt 

 43 /r . Elsewhere it may be more or less according to circum- 

 stances, more where fires have occurred at intervals sufficient to 

 repress competing species, less where time has sufficed for the 

 maturing of the forest and invasion, or where conditions of re- 

 production have established a mixed stand from the start. 



A summary of the biotic elements which enter into the 

 composition of the lodgepole species leaves no doubt as to its 

 fitness and capacity for distribution arid survival. Among these 

 several qualities may be mentioned as positive factors. First 

 may be mentioned the abundance of the seed produced, which 



