

FORESTS OF ROCKY MOUNTAINS FOREST RESERVE 29 



type. The second type has, in most cases, resulted from ancient fires that have 

 killed a pure spruce stand on low ground, and lack of seed-trees after the fire, or 

 repeated fires, have resulted in the occupancy of the area by grass. These meadows 

 are usually bounded by comparatively dense stands, of second-growth pine, or, some- 

 times, poplar, and the encroachment of the tree-growth on the grass-land is slow. 

 At the same time, grazing animals are not able to cause much damage to the dense 

 second-growth stands, or to enlarge the area of the grass-land. 



The other type, where the grass-land is in patches and the young growth is 

 irregularly distributed and not in dense solid stands, is much more subject to dam- 

 age from grazing animals. It is also in a much better position to become eventually 

 fully stocked with tree growth, since the areas to be seeded up are not in such large 

 units and the pine and poplar, which both become productive seed-trees at an early 

 age, are well distributed so that they can seed up the grass areas better where they 

 are confined to the edge. The grazing animals in this type penetrate all through 

 the area occupied by trees and break branches and tops of young trees, and trample 

 down \he young sprouts and seedlings. Areas where the value of the grazing is 

 small, and where a valuable stand of trees may be expected if the area be allowed 

 to stock itself fully with trees should be closed to grazing. At present, however, 

 most lands of this class at all attractive to grazers, have been excluded from the Forest 

 Reserve, and, in many cases, are held under grazing leases. 



Other forms of damage are caused by insects, porcupines, fungi, and dwarf mistle- 

 toe, but they will be discussed in relation to individual species. 



SILVICS. 



LIST OF SPECKS. 



The following species are found in the southern half of the Rocky Mountains 

 Forest Reserve: 



Pinus flexilis Limber pine. 



" albicaulis White-bark pine. 



" Murrayana Lodgepole or jack pine. 



Larix Lyallii Ly all's or alpine larch, or tamarack. 



Picea canadensis White spruce. 



" Engelmanni Engelmann spruce. 



Pseudotsuga mucronaia Douglas fir. 



Abies lasiocarpa Alpine fir (' balsam '). 



Populus balsamifera Balsam poplar. 



" tremuloides Aspen (poplar). 



Betula a1l>a. var. papyrifera. . . . Paper birch. 



DESCRIPTION OF SPECIES. 



ENGELMANN SPRUCE. 



With the exception of Douglas fir, which occurs in much smaller numbers than 

 it, Engelmann spruce is the largest tree of the region, and for that reason is most 

 sought after by the lumbermen. Lumber from it has numerous small, usually sound 

 knots, on account of the large number of branches which remain green low down on 

 the trunk. The crown is cylindrical with lower branches drooping somewhat. The 

 deep crown is also responsible for the rapid taper of the tree compared with other 

 species, since the diameter growth in the lower part of the trunk is better main- 



