Alaska birch
Alaska birch (Ea) - Betula neoalaskana
- Range and Amplitudes
- Tolerances and Damaging Agents
- Silvical Characteristics
- Genetics and Notes
Geographic Range and Ecological Amplitudes
Description |
Alaska birch is usually a tall shrub, less often, a medium-sized (<20 m) deciduous broad-leaved tree, at maturity with a narrow, oval crown, slender, often curved stem, and creamy white or slightly pinkish bark.
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Geographic Range |
Geographic element:
Western North American/Cordilleran and northern Central
Distribution in Western North America:
north and central in the Cordilleran region |
Ecological Amplitudes
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Climatic amplitude:
subarctic - (subalpine boreal) - montane boreal
Orographic amplitude:
montane - (subalpine)
Occurrence in biogeoclimatic zones:
(lower SWB), BWBS
Edaphic Amplitude
Range of soil moisture regimes:
(fresh) - moist - very moist - wet
Range of soil nutrient regimes:
very poor - poor - medium; oxylophyte
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Tolerances and Damaging Agents
Root System Characteristics |
Alaska birch, a wetland species, is shallow-rooted without a taproot. Roots are associated with ecto- and endo-mycorrhizae. |
Tolerances |
tolerance to |
tolerance class |
comments |
low light |
M |
may regenerate in open canopy stands |
frost |
H |
grows in permafrost soils |
heat |
L |
extreme heat is not a concern in boreal climates |
water deficit |
L |
absent on water-deficient sites |
water surplus |
H |
Tolerates wet sites and sites with a strongly fluctuating water table well |
nutrient (mainly N) deficiency |
H |
Very frequent in acid, very poor soils |
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Associated tree species and successional role |
Alaska birch grows scattered with other species in ombotrophic, poorly drained sites and wetlands, especially with black spruce. It is present in early seral, mid-seral, and even in late seral stages (on wet sites) of secondary succession. As a moderately shade-tolerant tree, Alaska birch maintains its presence as a variable component of open-canopy edaphic climax communities in ombotrophic wetlands. |
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Silvical Characteristics
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characteristic |
interpretive class |
comments |
reproduction capacity |
H |
early and frequent seed producer |
seed dissemination capacity |
H |
dispersed by wind |
potential for natural regeneration in low light |
L |
practically nil; developed mainly in canopy gaps |
potential for natural regeneration in the open |
H |
providing the presence of exposed mineral soil |
response of advance regeneration to release |
na |
advance 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 |
M |
increases with increasing stand density |
light conditions beneath closed-canopy, mature stands |
na |
closed-canopy stands are very infrequent |
potential productivity |
na |
non-crop species |
longevity |
L |
rarely >150 years |
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Genetics and Notes
Notes |
There are another three shrub birch species that occur frequently in interior British Columbia: shrub birch (Betula glandulosa Michx.), water birch (Betula occidentalis Hook.), and swamp birch (Betula pumila L.). All occur predominantly in boreal climates — shrub birch is an oxylophyte and diagnostic species for the SWB zone; water birch is a calciphyte represented mainly in subalpine boreal wetlands; and swamp birch is a component of montane boreal wetlands.
Alaska birch is not considered a timber crop species, however, it is a useful component of wetland subarctic and boreal ecosystems. |