268 UNIVERSITY OF COLORADO STUDIES 



evidently injured but did not fall for many years. To the north 

 of the park there are a few still standing, although now dead, which 

 were probably injured at that time. A few trees which have fallen 

 within the past ten years were over 200 years old at the time of their 

 death. 



The Development of the Lodgepole-Pine Forest. — After an area 

 has been burnt, the first trees to appear are the aspens. Later, 

 lodgepole pines appear among these. The ground becomes reseeded 

 by the opening of the cones which takes place on account of the 

 heat produced by the fire. When the lodgepoles reach a diameter 

 of about six inches, Engelmann spruces and subalpine firs may appear. 

 These trees do not grow until there is considerable shade. Here and 

 there are a few willows. Spruces and firs are much more abundant 

 on the steeper slopes and in moister places. The best developed 

 spruces are found on very moist slopes of about 35 degrees as is shown 

 in the forest on the north-facing slope at the western end of the park 

 and on the steep mountain south of East Lake. On very dry slopes 

 forestation may begin with the lodgepole pine without passing through 

 the aspen stage. 



The Close Formation. — At the northeast end of the park toward 

 Jenny Creek there is the best example of a lodgepole forest. Here 

 the stand is very close and the trees vary in size from seedlings to 

 those that are almost two feet in diameter. The larger trees must 

 be about 1 20 years old, and of a height of 58 feet. The best-developed 

 and largest trees are found on a slope of about six degrees and in 

 comparatively dry soil. The forest contains not only lodgepole 

 pines but also Engelmann spruces and subalpine firs. The spruces 

 and firs are younger and smaller trees, most of them not reaching 

 a diameter greater than four inches. The number of spruces and 

 firs in a given area of the forest varies, but in general we may say 

 that to every one hundred pine trees there are about four spruces 

 and one fir. Deeper in this forest, as the soil is more moist and the 

 slope becomes greater, the spruces and firs increase in number and 

 size. At Jenny Creek the spruces and firs are as large and well 

 formed as the largest of the lodgepole pines. Some very large Engel- 



