Open forest or woodland to 15m tall on sites protected from the wind or forming a low krummholz on exposed sites at timberline. The understory of dwarf shrubs and perennial herbs is varied and abundant in moist sites, sparse in dry sites or where the forest is dense. The trees are slow-growing and long-lived. Tsuga martensiana is a dominant or important component in the Klamath Ranges and northern Sierra Nevada, but becomes less important, increasingly replaced by Pinus albicaulis or Pinus contorta ssp. murrayana from the central Sierra southward. Flowering and growth is concentrated in midsummer, with most plants dormant for 9-10 mos. On dry sites, growth of the smaller plants may be limited by drought in late summer.
SITE FACTORS:
Occurs on sites with long, severe winters and brief, cool summers. Most common near timberline. Similar to the high elevation stands of Lodgepole Pine Forest (86100) but probably somewhat cooler and moister. Subject to strong, desiccating winds on ridges and near timberline. Usually confined to moist, protected, north-facing slopes in the southern portion of its range. Generally on rocky, well-drained sites. Usually occurs above Lodgepole Pine Forest (86100) or, toward the north, Red Fir Forest (85310). On drier sites intergrades with Whitebark Pine-Lodgepole Pine Forest (86220) or, in the Klamath Ranges, Foxtail Pine Forest (86300). Replaced above timberline by Alpine Fell-Fields (91100).
DISTRIBUTION:
Scattered in the Klamath Ranges of Siskiyou and northern Trinity Cos., on the high peaks of the Salmon Mtns., Scott Mtns., and Trinity Alps. Occurs on the slopes of Mt. Shasta and more abundantly on Mt. Lassen. In the Sierra Nevada from the peaks around Lake Tahoe southward to the headwaters of Bubbs Creek, Fresno-Tulare Co. line. Becomes relatively scarce and is largely replaced by Whitebark Pine-Lodgepole Pine Forest (86220) south of Yosemite and Mammoth Mtn. Well developed in portions of the Cascade Range in Oregon and Washington. Elevation about 7,000-8,000 feet (2100-2420m) in northern California and 9,000-11,000 feet (2700-3330m) in the south.
UPDATE: 11/97
Source: Holland, 1986
Digital Text: NatureBase