396 BITTER ROOT FOREST RESERVE 



most precipitous ridges, especially on the southern slopes, are 

 found straggling trees, but for the purpose of graphic illustra- 

 tion it has been represented as it has. 



Along tbe crest the growth is very sparse, but as the project- 

 ing spurs reach out to the westward and attain lower altitudes 

 the} r are usually covered with a forest growth, except where their 

 sides are too precipitous to admit of vegetation. There are on 

 the western slopes of the Bitter Root mountains three primary 

 forest zones, namety, the subalpine fir, the white pine, and the 

 yellow pine. The subalpine-fir zone extends from the crest alti- 

 tudes to about 5,800 feet above sea-level and includes the white- 

 bark pine, the lodge-pole pine, the Engelmann spruce, the Lyall 

 larch, and the subalpine fir. The white pine zone has an ap- 

 proximate range from an altitude of 5,800 feet to about 2,000 

 feet, and includes the white fir, the lodge-pole pine, the Engel- 

 mann spruce, the cedar, and the yew. The yellow-pine zone 

 extends from elevations of 2,500 feet in the valleys to nearly 

 6,000 feet on the western and southern slopes, and to 4,500 on 

 the northern and eastern slopes, and includes the yellow pine, 

 the white fir, the hemlock spruce, the lodge-pole pine, the west- 

 ern birch, the paper birch, the balm of Gilead poplar, and the 

 aspen, besides various willows and alders. The distribution of 

 the growth in the subalpine zone is about the same as in the 

 similar zone east of the crest. The trees constituting the white- 

 pine zone are divided approximately into three equal portions, 

 the white fir forming one portion, the cedar the second, and the 

 lodge-pole pine and Engelmann spruce the third. The species of 

 trees occurring in the yellow-pine zone may be divided approx- 

 imately into two portions, the hemlock spruce constituting one 

 and the yellow pine and white fir the other, the former, however, 

 being about three times more abundant than the latter. From 

 the foregoing it will be observed that at least 98 per cent of the 

 trees in the Reserve are coniferous, the exceptions being a few 

 cottonwoods, maples, and various bushes bearing berries. 



The most striking feature presented by this map is the large 

 portion of it that has been burned over, nearly all of it having 

 been visited at different times b}' fires and at least one-third of 

 the standing timber having been destroyed. The map indicates 

 clearly the burned zones, and an attempt has been made to show 

 by the percentage figures the proportion of the timber that has 

 been completely destroyed. 



