Larix lyallii

Parlatore 1863

Common names

Alpine larch, mountain larch, tamarack (Peattie 1950), mélèze de Lyall (Parker 1993).

Taxonomic notes

Larix lyallii and L. occidentalis (Larix sect. Multiseriales) are similar morphologically and have similar geographic ranges. Just how closely the two species are related has not been determined, but they probably originated from a common ancestor resembling L. potaninii Batalin (Parker 1993). They may hybridize where their ranges overlap (Parish et al. 1996).

First described by Scots naturalist David Lyall in 1858 (Parish et al. 1996).

Description

Trees to 25 m tall with dbh to 120 cm; crown sparse, conic to irregular. Bark thin, smooth, yellowish grey when young; becoming furrowed and flaking into red- to purple-brown scales with age. Branches horizontal, occasionally pendulous, often gnarled and irregularly spaced, persistent on trunk when dead; twigs strongly white- to yellow-tomentose for 2-3 years. Buds tomentose, scale margins ciliate. Needles deciduous, in bunches of 30-40 on short shoots 20-35×0.6-0.8 mm, 0.4-0.6 mm thick, keeled abaxially, 2-angled adaxially, light green, turning golden yellow in autumn; resin canals 40-80 µm from margins, each surrounded by 6-10 epithelial cells. Ovulate cones elliptic, upright, red when young, turning purplish and then brown with age, 2.5-4(5)×1.1-1.9 cm, on curved stalks 3-7×2.5-4 mm; scales 45-55, rounded, margins erose, abaxial surface tomentose at maturity; bracts tipped by awn 4-5 mm, exceeding mature scales by ca. 6 mm. Pollen 78-93 µm diam. Seeds yellow to purple, body 3 mm, wing 6 mm (Parker 1993, Parish et al. 1996).

Range

Canada: Alberta and British Columbia; USA: Washington, Idaho and Montana at 1800-2400 m (Parker 1993). It is locally common on exposed northern subalpine slopes to timberline, often with very rocky soils. It has very low shade tolerance and, due to its thin bark, low fire tolerance (Parish et al. 1996). See also Thompson et al. (1999). Its deciduous habit confers resistance to winter desiccation, permitting this species to reach timberline elevations that may be far above other conifers, and to retain an erect growth form on those sites.

Although the geographic ranges of Larix lyallii and L. occidentalis overlap considerably, elevational differences of 150 to 300 m usually separate them. Some morphologically intermediate specimens have been collected from Washington and Montana (Parker 1993).

Big tree

Height 29 m, dbh 191 cm, crown spread 17 m, in Wenatchee National Forest, WA (American Forests 1996).

Oldest

Margaret Colenutt collected a sample with 838 rings near Waterton, BC; most or all of this is a crossdated age (Luckman 2006). There is also a ring-counted age of 791 years for sample COL-6A collected from a stand above Colchuck Lake in the Alpine Lakes Wilderness of WA by C.J. Earle in 1986. This is a pith date, but on a scarred core that may be missing some rings in the early 1300s. The tree was only about 40 cm diameter at the core height, a fine illustration of the rule-of-thumb that exceptionally old trees tend not to be particularly large ones. There's also a crossdated age of 728 years for a specimen from W Alberta collected by B.H. Luckman (Brown 1996). I believe this is from a living tree, collected in the late 1980s or early 1990s.

Dendrochronology

Many collections from the North Cascades of WA and the Canadian Rockies. E.g., Colenutt and Luckman (1991).

Ethnobotany

Due to its small size and remote occurrence, its principal values are scientific (see "Dendrochronology") and aesthetic. Few trees are lovelier, either in spring when the soft green of the needles contrasts with deep snowdrifts still covering the ground in this species' alpine habitat, or in autumn, when its golden foliage complements the red of huckleberries and the icy blue of the sky.

Observations

Many very fine stands are to be found in the eastern Cascade Mountains, including the Alpine Lakes, Glacier Peak and Pasayten Wildernesses, North Cascades National Park (WA), and Manning Provincial Park (BC). It is also widespread and exemplary in much of the Canadian Rockies, such as in Banff National Park.

Remarks

Mountain goats, bighorn sheep and black and grizzly bears all feed in alpine larch stands. Blue grouse feed on the needles (Parish et al. 1996).

Citations

Colenutt, Margaret E. and Brian H. Luckman. 1991. Dendrochronological investigation of Larix lyallii at Larch Valley, Alberta. Canadian Journal of Forest Research 21: 1222-1233.

Luckman, B.H. 2006. Current research. http://geography.uwo.ca/facilities/dendro/tree-ring-research.pdf, accessed 2007.10.22.

See also

Arno and Habeck 1972.

Bakowsky, O.A. 1989. Phenotypic variation in Larix lyallii and relationships in the larch genus. M.Sc.F. thesis. Lakehead University.

Burns and Honkala 1990.

Carlson 1965.

Carlson et al. 1991.

Farjon (1990) provides a detailed account, with illustrations.

FEIS database.

Knudsen 1968.

Owens and Simpson 1986.