Lodge Pole and Yellozv Pine Distribution. 511 



by fire, but from the pole stage up the Yellow Pine becomes one 

 of the most fire resistant of the Western pines, while in this re- 

 spect the Lodgepole changes but slightly in the course of its 

 development. 



Yellow Pine may begin to bear fertile seed at from twenty- 

 five to thirty years of age but does not produce abundantly until 

 very much older. The seeds fall from the cones during the early 

 Autumn and germinate at once or early the next Spring. Very 

 few of them hold their fertility over to a second season. 



Lodgepole Pine, on the other hand, begins to bear seed at 

 from seven to ten years in the open and even in dense stands 

 produces a heavy crop practically every year after it reaches an 

 age of from twenty to twenty-five years. The cones usually 

 remain on the tree and many of them do not open for years, the 

 seed remaining fertile indefinitely. For its early growth Yellow 

 Pine requires a light shade, but later it becomes very intoler- 

 ant so that the understory in a pine forest contains little Yellow 

 Pine, except in the openings. While Lodgepole Pine makes its 

 best growth in full sunlight it is able to survive for many years 

 in the shade of a high forest and is frequently found as an under- 

 story with Yellow Pine. Both species will grow on a wide va- 

 riety of sites and soils, but Yellow Pine absolutely requires a 

 good drainage. In this respect it is essentially different from 

 Lodgepole Pine, which will grow under almost any condition of 

 moisture from a dry, rocky ridge to the wet swampy borders of 

 lakes and streams. 



A striking feature in the distribution of the species in these 

 forests is the distinctness and the regularity of the types. On 

 wide pumice flats there is an unbroken stand of pure Lodgepole 

 Pine. One may travel for miles without seeing the slightest 

 change in the timber cover or topography, but with the first 

 butte comes a change in the forest type. Where the slope breaks, 

 almost on the contour line, Lodgepole Pine gives way to the old 

 Yellow Pine which covers the hill above it ; and on every knob 

 or knoll the same conditions are true. Sometimes, of course, 

 Lodgepole Pine may be found on the buttes but in such places 

 it has come in following fire in the Yellow Pine stand. WTiere 

 there is any mixture of species it is the Lodgepole Pine which 

 has come in under the Yellow Pine on the slopes, and never a 

 mixture of Yellow Pine coming in on a Lodgepole Pine fiat. 



