138 ABSAROKA DIVISION OB' YELLOWSTONE FOKEST RESERVE. 



The forest appears in three general zones or strata, which blend where they 

 meet and are not closely differentiated, though fairly well marked in their central 

 areas. The upper zone, stretching to timber line at 9,500. to 9,800 feet, is composed 

 of Engelmann spruce, subalpine fir, and white-bark pine, with the addition of lodge- 

 pole pine in varying proportions at the lower limits. The spruce forms the largest 

 percentage of the zone, followed by white-bark pine and subalpine fir. Occasionally 

 this arrangement is reversed and white-bark pine takes the lead or even subalpine fir 

 may hold the dominant place; but in stands where a normal ratio has been established 

 spruce always leads. The stands of this zone are open and scattered at their upper 

 limits and are often very compact and densely stocked at their lowest. The open 

 stands are set in grassy tracts or fire glades which have only partly restocked since 

 they were burned over. The subalpine forest contains little mill timber. Its chief 

 value lies in the stability it imparts to the upper slopes and in the volume of fuel 

 and mine timber it is capable of- supplying. 



The central zone consists of well-stocked stands composed of red fir, lodgepole 

 pine, and Engelmann spruce, lodgepole pine constituting the dominant species. In 

 some localities at the lower levels of the zone red fir becomes the chief species, and 

 occasionally along the stream margins in the lowest canyons Engelmann spruce 

 predominates. The bulk of the forest in the quadrangle occurs in this zone, both 

 the saw timber and the pole and fuel size. 



The lowest zone in the series borders the plains, or the woodlands when wood- 

 lands are present. The forest in this zone commonly is open and more or less broken, 

 its heaviest stands occurring on the northern slopes of ridges and canyons where the 

 semiarid conditions of the nearby plains are less^ marked. It is composed of red fir, 

 yellow pine, limber pine, and small proportions of Engelmann spruce along the 

 streams. Red fir is always the dominant species in this zone, the other coniferous 

 species constituting only a small percentage. 



The proportion of the coniferous species in the forests of the quadrangle is 

 shown in appended table. 



Composition of the forest in the Livingston quadrangle, Montana, including trees of all species with basal 



diameters of 4 inches and upward. 



Per cent. 

 Limber pine 3 



■ Lodgepole pine 42 



White pine less than . 1 



White-bark pine 5 



Yellow pine ; .5 



Bed fir , 30 



Subalpine fir 4 



Engelmann spruce 15 



Aspen and cottonwood 4 



