1904 FORESTRY AND IRRIGATION 505 



Alpine fir, which eventually form the these inferior trees that make the dry 

 trees in mixture. At the foot of moun- dead and down stuff so common in 

 tain slopes along ravines and creeks, the pure lodgepole pine forest. 

 Alpine fir and Engelmann spruce are The fact that lodgepole pine does 

 the predominant species in mixture not come up under much shade deter- 

 with lodgepole pine; then as we as- mines largely the composition of the 

 cend the mountain, we pass through forest. If much light is required for 

 a broad zone of almost pure lodgepole, the growth of seedlings, it means that 

 extending for two or three thousand the forest will either be open in char- 

 feet in elevation ; coming out near its acter, consisting of trees of varying 

 upper edge, we meet with red fir on ages, or else it will be dense and all 

 the ridges and rocky slopes ; then near the trees of practically the same age. 

 the top of the mountains the Alpine Lodgepole pine forests occur in both 

 pines and Alpine types occur. In gen- of these forms, but the latter is the 

 eral, the statement is true, that wher- most typical and common, 

 ever lodgepole pine is found the pre- Reproduction of lodgepole pine is 

 vailing species is lodgepole. so closely interwoven with the ef- 

 In the northwest, west of the Rocky fects of fire that we might say the 

 Mountains, in Idaho, and Washing-- prime cause of new stands of lodge- 

 ton, the Ibdgepole pine was frequently pole pine is the result of a burn, 

 observed to occur in pure stands; but Like the jack pine of the Lake 

 cedar, hemlock, silver pine and bull States, the lodgepole pine cones do 

 pine occasionally form a considerable not open immediately after maturity, 

 percentage of the stand in mixture, but the scales remain closed from two 

 In Wyoming and Colorado, the bull to ten years, or until made to open by 

 pine and Colorado blue spruce grow heat. During this time, the ripe seed, 

 with it. protected by the cone scales, remains 

 Lodgepole pine is quite intolerant intact and seems to lose none of its 

 of shade, especially so when young, vitality. Young seedlings of lodgepole 

 Very few seedlings of lodgepole pme pine spring up very abundantly on 

 are found growing in the dense virgin burned over districts, and soon clothe 

 forest. The young plant will not grow the entire ground with a dense cover : 

 under a heavy shade of forest trees, of reproduction. 



It is only on exposed areas that lodge- A fire passing through a lodgepole 



pole comes up thick and vigorous, forest kills the trees, but unless tlvj 



When the conditions are most favor- fire is severe, leaves the trees standing 



able, as on a steep hillside where the and the heat of the fire is sufficient 



light can enter from the sides, and to open the cones, but not enough to 



where the soil is firm and of suitable destroy them. The winged seeds now 



quality, it is then possible for seed- set free are blown long distances, finai- 



lings to come up under the old trees, ly lodging on the ground, and becorrv- 



The young slender trees in the pole ing partially covered by the next rain, 



forest stage, growing very thickly to germinate very readily, and grow up 



gather, persist tenaciously in' the in the open, forming a very dense cov- 



struggle for dominance, even when er. 



only the tip of the crown receives light Because of its very thin and tender 



from above. In such cases the top is bark, the lodgepole pme is extremely 



very short and thin and the tree is :i sensitive to fire; a mere ground hre 



tall, slender pole. The larger trees often doing considerable injury to 



exist and do fairly well under partial whole forests. A severe ground fire 



shade, as when growing in rather open will not only scorch the trunk badly, 



forests in mixture with Alpine fir and but will burn deep into the wood 



Engelmann spruce ; in the pole forest and will either leave a mere shell of 



the overtopped trees succumb to death trunk, or will completely girdle it, tin-. 



very slowly. It is the killing off of entirely killing the tree. Perhaps 



