Subalpine larch

Subalpine larch (La) - Larix lyallii

Subalpine larch, also called alpine larch, is a small- to medium-sized (rarely >30m tall), deciduous conifer, with a short, sturdy, and tapering stem; ragged, broad irregular crown; and yellowish-gray bark, with irregularly shaped, scaly plates.

It is an ecologically interesting and aesthetically attractive species but its wood has little commercial value.

On this page

• Geographic range and ecological amplitudes
• Tolerances and damaging agents
• Silvical characteristics
• Genetics and notes

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Geographic range and ecological amplitudes

Geographic range 

Geographic element

Distribution in Western North America:central in the Cordilleran region

Ecological amplitudes 

Climatic amplitude:

(alpine tundra) - subalpine boreal

Orographic amplitude:

subalpine - (alpine)

Occurrence in biogeoclimatic zones:
(lower AT), upper - (lower) southern ESSF

Subalpine larch is well adapted to a continental subalpine boreal climate. It grows in the transition between the upper southern portion of the ESSF zone and the adjacent AT zone between 1800m and 2300m. It forms a timberline there together with subalpine fir, (Engelmann spruce), and whitebark pine. It tolerates very severe winters (the absolute minimum of -56 degrees C has been recorded). Occasional chinook winds of very dry air during the winter rarely affect subalpine larch to a lethal degree because of its deciduous habit, while evergreen conifers may be severely affected because moisture lost rapidly from foliage cannot be replaced.

Edaphic amplitude

Range of soil moisture regimes:
(moderately dry) - slightly dry - fresh - moist - very moist - (wet)

Range of soil nutrient regimes:
poor - medium - rich - (very rich); calciphytic

The nutrient amplitude of subalpine larch is not well known. Field studies indicate that it is absent on very poor sites and grows somewhat better on calcium-rich substrates, such those derived from calcareous quartzites, sandstones, or argillites. However, very rapidly drained limestones are less favorable substrates in drier climates than other sedimentary and igneous rocks.

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Tolerances and damaging agents

Root system characteristics

Subalpine larch roots extend deep into fissures in skeletal or rocky substrates. Trees are very windfirm as they are well anchored by a large taproot and several large lateral roots. The crown and trunk of old trees may break off in storm winds but the trees themselves are seldom uprooted. Roots of subalpine larch are associated with both ecto- and endo-mycorrhizae.

Tolerances

Tolerance to	Tolerance class	Comments
Low light	L	A very shade tolerant, exposure requiring species
Frost	H	.Low growing season temperatures are common in subalpine forests
Heat	L
Water deficit	M	Droughts are uncommon in upper subalpine forests
Water surplus	H	Infrequent on waterlogged sites
Nutrient (mainly N) deficiency	M	Tolerates poorly strongly acidic soil

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Damaging agents

Damaging agent	Resistance class	Comments
Snow	H	Common in snowslide and avalanche areas
Wind	H	Common on exposed ridges.

Risk

	Risk class
Fire	L	Not a major concern in upper ESSF forest
Insect	L
Fungi	L	Not a serious concern in the upper ESSF forest (brown trunk rot, larch needle blight)

Associated tree species and successional role

In British Columbia, subalpine larch grows more in pure stands of irregular size and scatter clumps rather than in mixed-species stands. It typically forms open, park-like groves, <0.02 ha in size, interspersed with opening of various sizes. Subalpine larch is a pioneer species (primary succession) on snowslides, collovium, and rock outcrops, and may be present as a minor component in the upper ESSF forest.

Subalpine fir	L	upper southern ESSF
Engelman spruce	L	upper southern ESSF

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Silvical characteristics

Characteristic	Interpretive class	Comments
Reproduction capacity	L	Infrequent cone crops, low percentage of sound seed
Seed dissemination capacity	?	Not reported
Potential for natural regeneration in low light	L	Practically nil, a very shade intolerant exposure requiring species
Potential for natural regeneration in the open	H	Provide the presence of exposed mineral soil
potential initial growth rate (<5 years)	L	Very slow for the first 25 year.
Response of advance regeneration to release	na	Advanced regeneration does not develop in the absence of adequate light and seedbeds
Self-pruning capacity in dense stands	na	Dense stands are very infrequent.
Crown spatial requirements	H	Wide long crowns except in dense stands where crowns are short
Light conditions beneath closed-canopy, mature stands	na	Close-canopy stands are very infrequent
Potential productivity	na	Non-crop species, site indexed functions are not available, the maximum reported size in 29m, dbh 201cm.
Longevity	H	Typically up to 500 years, oldest trees estimated over 1000 years

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Genetics and notes

Genetics

Races, varieties, or subspecies of alpine larch are not known.

Notes

Considering the ecosystems in which it grows and its productivity, subalpine larch is  not a timber crop species but a valuable timberline species for watershed protection, wildlife habitat and outdoor recreation.

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