MOUNT RAINIER The Forests of Mount Rainier National Park

WESTERN HEMLOCK (TSUGA HETEROPHYLLA)

Next to the Douglas fir the western hemlock is the most abundant tree in the forests of Oregon and Washington. It occurs from Alaska southward to northern California. About Mount Rainier it is found up to an altitude of 5,000 feet. In the river valleys in moist situations it is a large tree, sometimes reaching a height of 250 feet and a diameter of 5 feet. On the high ridges it is stunted. It grows best on moist, deep soils in dense forests, but thrives under almost all conditions of soil and exposure if provided with plenty of moisture.

Western hemlock (figs. 6 and 7) is usually associated with Douglas fir and red cedar, but sometimes forms a forest of nearly pure growth. The hemlock produces abundant seed each year, although it is more prolific at irregular intervals. The seeds germinate readily on decayed moss and rotten wood as well as upon the mineral soil. Seedlings frequently grown on fallen logs and extend their vigorous roots around the side until they reach the ground and become firmly anchored in it. Young hemlocks thrive in shade. On logged-off areas which have not been burned over and which are partially shaded by uncut trees, the reproduction of hemlock springs up, to the exclusion of the more valuable Douglas fir.

Fig. 6.—The lower slope forest, near Longmire Springs, altitude 3,000 feet, here composed largely of western hemlock (Tsuga heterophylla); the tree on the extreme left is a Douglas fir Pseudotsuga taxifolia). Photograph by A. H. Barnes.

The hemlock is long lived and grows slowly. The largest trees are from 200 to 500 years old and are usually hollow-hearted. The bark is thin and the tree very easily killed by ground fire. The wood of the hemlock is tough, light and straight grained. It is not as durable as the Douglas fir and decays rapidly when exposed to the weather. The clear lumber is suitable for interior finish. The wood is also used for flooring, joists, lath, and paper clip. The common and rough lumber does not find a ready market, except for the limited amount used in temporary construction. The western hemlock is, however, superior to the eastern hemlock, and its value will probably be recognized as its usefulness for many purposes becomes better known.

Fig. 7.—A forest of Douglas fir, with an understory of western hemlock, on the lower slopes of the hills, Mount Rainier National Park. Photograph by A. H. Denman.