Ecology of Alpine Larch (Larix lyallii Parl.) in the Pacific Northwest

• Published in: Ecological Monographs
• Main Authors: Arno, Stephen F., Habeck, James R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1972
• Subjects: Ecology, Evolution, Behavior and Systematics; Pacific; Tundra
• Online Access: http://dx.doi.org/10.2307/1942166; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F1942166; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F1942166; https://onlinelibrary.wiley.com/doi/pdf/10.2307/1942166; https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.2307/1942166

Alpine larch (Larix lyallii) grows in or near the timberline zone on high mountains of the inland northern portion of the Pacific Northwest. Unlike other subalpine conifers, which are evergreens, this deciduous larch displays an affinity for cold rocky sites and often grows in tree form higher up on north slopes than even krummholz (shrubby) forms of its associates. Overstory and understory vegetations in alpine larch communities were only indirectly correlated. Vaccinium scoparium, Luzula glabrata, and Phyllodoce empetriformis were the most common understory dominants. The distinctly snowy—cold—timberline nature of alpine larch habitats is emphasized by the presence of Cassiope mertensiana, Phyllodoce glanduliflora, and Abies lasiocarpa krummholz among the 11 most common understory species. Unlike the larch, which is generally restricted to the timberline zone, nearly all associated plants have broader distributions in the subalpine forest proper or above tree limit. Alpine larch is a climax species on a wide variety of sites too severe for the more shade tolerant evergreens to form unbroken stands because of shortness of growing season, rock terrain, avalanches, blizzards, or extreme dryness or bogginess. When alpine larch ascends into what would otherwise be a strictly alpine habitat (above the limits of other conifers), its stands apparently modify the surface environment since subalpine understory species are generally able to ascend with it. Rarely the undergrowth is dominated by tundra species. Alpine larch is superior in invading freshly glaciated sites. The positive correlation of alpine larch to acidic substrates poor in mineral ions is in contrast to the substrate relationship of many other timberline conifers, which are calciphiles.