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The Cone-bearing Trees of Yosemite (1939) by James E. Cole


WHITE-BARK PINE

Pinus albicaulis Engelmann.

White-bark Pine, Pinus albicaulis
[click to enlarge]
White-bark Pines must be the hardiest of all Yosemite trees for these bushy, timber-line dwellers creep out upon bleak passes and well up our loftiest mountains, the pioneers of the tree clan in their conquest of the peaks. In summit passes or at the upper limit of tree-life, where they are exposed to extreme daily and seasonal changes of temperature, and to fierce winds and long seasons of snow, Whitebark Pines form characteristic “forests” of scattered sprawling mats.

At lower elevations where they associate with Lodgepole Pines and Mountain Hemlocks, the White-bark Pine may grow from fifteen to forty feet high and one to two feet in diameter forming a small tree of erect habit. But as they struggle, solitary and companionless, up the inhospitable peaks, these mountaineers become more and more prostrate until finally at timber-line they are more like carpets than shrubs or trees. The gnarled, twisted trunks, unable to raise their tops in normal pine fashion are forced to sprawl along the ground. The short, massed shoots which clothe the spreading branches are beaten down by the heavy blankets of snow and clipped smooth by the furious gales of winter.

In utter disregard of such rigorous climate, these dauntless Whitebark Pines live to a more advanced age than many pines of the lower, more hospitable forest belt. Growth rings of stunted specimens may average 100 per inch. John Muir counted 255 annual rings in one tree not three feet high and only three and one-half inches in diameter. Another trunk six inches across was 426 years old and a branch one-eighth inch in diameter had lived for 75 years.

It is from the characteristic white bark of the young trunks that these pines received their name. The bark of young trees and that on the upper branches of old trees is smooth and almost white, or at times rosy. On mature specimens the trunks are roughened by small, reddish or yellowish-brown scaly plates, making it difficult to distinguish them from the lodgepoles. In common with that of the Lodgepole Pines, but differing from other Yosemite pines, the bark is very thin, rarely more than one-half inch thick even at the base of old trunks.

Identification of White-bark Pines in the Yosemite region is made certain by its high mountain habitat. The leaves are in bundles of five growing densely clustered only at the ends of the branchlets. The five dark blue-green, short needles, one and one-half to two and three-quarters inches Iona, are rigid and so closely compacted in the bundle as to resemble the needles of Lodgepole Pines. That species, however, has only two needles in each bundle so would not be confused if examined. Another associate of the White-bark Pine, the Mountain Hemlock, has needles singly arranged on the branches.

In keeping with their singular manner of growth, the cones are unlike any other Yosemite pine or any other North American Pine in that they break up while still attached to the trees and fall to the ground scale by scale. The purplish, pitch-covered, glassy cones, clustered at the ends of the upper branches in true white pine fashion are seldom found for the Clark’s Nutcrackers and Alpine Chipmunks quickly tear them apart in their quest for food.

Climbing the granite peaks of Yosemite, one is surprised to discover that White-bark Pines avoid the alpine “gardens.” Instead, they very nearly always are found growing under, around, or over large boulders. Whether this is due to the boggy condition of these meadows, to the protection from gales afforded by the boulders or to the fact that snow melts more quickly from the rocks than from the level places has not been determined. Visit their haunts and see if you can solve this problem.

The most accessible place in which to see and study White-bark Pines in Yosemite is at the summit of the Tioga Road. Here they are found near the highway, and are upright trees. Several fine specimens stand within a few yards of the parking area directly in front of the Tioga Pass Ranger Station. There they may be observed also in their prostrate form fringing the mountains at timber-line everywhere. It is worth a half mile hike to the top of the ridge behind the Tioga Pass Ranger Station to learn about them at first hand. Intimate association with White-bark Pines in all their varied forms will make clear the comprehensive statement of J. Smeaton Chase, “Last of all and least of all, yet in some ways finest of all the Sierra tree-clans, comes the dwarf pine.”



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