32 Forest Club Annual 



limber pine although it seems to endure even drier soils. The 

 aspen, Populus tremuloides, is a very conspicuous tree in this 

 zone, forming groves of small trees over wide areas. Englemann 

 spruce, Picea engelmanni, also makes it first appearance in the 

 upper stretches of this zone, but becomes of more importance in 

 the zone above. 



Throughout the mid-forest zone much of the forest has 

 been burned, and the problems of fire and of seeding after the 

 fire are many. Interesting and important studies can be made 

 of the relation of fire to the destruction of merchantable timber, 

 to the preparation of the seedbed, and to the opening of the 

 cones of the lodgepole pine. Very commonly burned-over 

 areas are stocked with a full stand of other species before the 

 conifers come in. These species are often of great value in the 

 early history of the coniferous forest. 



4. The Subalpine Forest Zone. 



This zone ranging from an altitude of 10,000 feet to 11,500 

 feet is characterized most generally by forests of Engelmann 

 spruce, Picea engelmanm. Limber pine and subalpine fir, 

 Abies las ocarpa, are important secondary species in many 

 localities although neither of these species forms as close stands 

 as is the case with the spruce. Engelmann spruce often forms 

 large pure stands. The . species demands a rather moist soil, 

 reaching its best development on the rich retentive loams of 

 north exposures in gulches and canons. The shallow root system 

 enables it to grow in shallow soils. The species is very tolerant 

 of shade, far exceeding its two common associates in this respect. 

 It is a prolific seeder after about the twenty-fifth year. Heavy 

 seed years occur at intervals of 3-4 years and the seed is of high 

 rate of germination. Notwithstanding its great seed production 

 seedlings are not so abundant as would be expected. They usually 

 occur in small protected openings in the older forest. In such 

 places the small trees are sometimes so thick that it is impos- 

 sible to penetrate to the center of the thicket without cutting 

 the trees. 



As has been said limber pine never forms close stands, but 

 on the other hand occurs singly or in groups under a wide range 

 of soil conditions. At timber-line this species is often found on 

 the exposed ridges alternating with Engelmann spruce in the 

 canons. At this altitude, about 11,500 feet, the limber pine, 

 ordinarily an irregular tree as to form, assumes the most fan- 

 tastic shapes. The trees may be eight inches in diameter and 

 only six feet tall with live branches only on the side away from 

 the wind. Toward the windward portions of the trunk are in 



