SURVEYS OF FOREST RESERVES. 85 



On swampy lauds and in the river bottoms the Engelmaun spruce is 

 common. It is a comparatively small tree, slow in growth, and with 

 but moderate reproductive power. Its average dimensions may be given 

 as follows: Height, 100 feet; diameter, 1.5 feet; length of clear trunk, 

 10 feet. 



Wherever the old forest has been destroyed by flre, the lodge-pole pine 

 is very apt to take its place. This tree is singularly liable to be killed by 

 flre ou account of its thiu and resinous bark, but its wonderful powers 

 of reproduction, perhaps superior to those of any other tree .on this con- 

 tinent, enable it to repair damages from this source with astonishing 

 speed. It is frequently found as an undergrowth beneath fire-scarred 

 old trees of larch and Douglas fir (red. fir), and its sylvicultural function 

 appears to be to prepare the ground for its more valuable successors. 



The alpine flr occurs throughout this forest chiefly as undergrowth. 

 Mature trees are infrequent, but the younger ones are common, occupy- 

 ing both moist and dry situations, although with a preference for the 

 former. They do not flourish except under cover of other trees. Old 

 trees reach average dimensions somewhat as follows: Height, 100 feet; 

 diameter, 2 feet ; length of clear trunk, 25 feet. This tree has little or 

 no commercial value at present. 



In the more level stretches of the upper valley of Swan River the yel- 

 low pine has taken almost exclusive possession of the ground, and it is 

 probable that the higher portion of the South Fork drainage is to some 

 extent similarly occupied. The upper valley of the Big Blackfoot in 

 and near the reserve also contains large bodies of yellow pine, and great 

 quantities of lumber from this tree have been cut from its tributaries. 



FIRB, WESTERN SLOPE. 



Here as elsewhere flre has been followed by the extension of the 

 lodge-pole pine. Considerable burns exist on the South Fork and in 

 the valley of Swan Eiver, near their respective junctions with Flathead 

 Eiver and Flathead Lake. Isolated burned patches are elsewhere dis- 

 tributed through the forests. The South Fork is comparatively an 

 unknown region, little visited and difficult of access, while Swan Eiver 

 Valley contains a good trail throughout its length and is comparatively 

 well known. There is also a good trail down the Middle Fork. In the 

 upper portion of the valley of Swan Eiver and in the region tributary 

 to the Big Blackfoot the prevalence of the western yellow pine, whose 

 heavy bark enables it to resist many surface fires, has had a strong 

 tendency to check the damage from fire, and the same is probably true 

 about the head waters of the South Fork, where the forest is said to be 

 similar in general character. 



WATER, WESTERN SLOPE. 



Floods in the South and Middle forks will have serious consequences 

 for the Flathead Valley. Swan Eiver, which empties into Flathead 

 Lake, is somewhat less important in this respect. The function of the 

 forests in the drainage basins of these streams in restraining floods will 

 probably be of greater moment to residents of their valleys below the 

 reserve than their effect on agriculture through irrigation. 



MINING, WESTERN SLOPE. 



Mining has received no considerable extension on any of these 

 streams. Coal has been found, but there are no sufficient reasons 

 under this head for excluding any portions of this area from the 

 reserve. 



