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Life History and Disturbance Response of Betula lenta (sweet birch)
Family: Betulaceae
Guild: opportunistic, long-lived intermediate
Functional Lifeform: medium-size deciduous tree
Ecological Role: found on moist, well-drained soils; often a component of hardwood mixtures that developed under second-growth, old-field white pine; also may grow as advance regeneration in canopy openings or under hardwood stands with light to moderate crown densities
Lifespan, yrs (typical/max): 150/250
Shade Tolerance: intolerant
Height, m: 15-20
Canopy Tree: yes
Pollination Agent: wind
Seeding, yrs (begins/optimal/declines): 40/40/70
Mast Frequency, yrs: 1-2
New Cohorts Source: seeds or sprouts
Flowering Dates: late spring
Flowers/Cones Damaged by Frost: yes
Seedfall Begins: early fall
Seed Banking: 1 yr +
Cold Stratification Required: yes
Seed Type/Dispersal Distance/Agent: winged nutlet/ to 200 m/ wind
Season of Germination: spring
Seedling Rooting System: variable
Sprouting: common
Establishment Seedbed Preferences:
Substrate: humus, rotten wood, mineral soil
Light: open areas only
Moisture: moist required
Temperature: neutral
Disturbance response:
Fire: Fire is probably rare (occurring at intervals of decades to centuries) on the moist upland sites where sweet birch commonly grows. Little information is known about the response of sweet birch to fire, but it would likely increase during long fire intervals. This extremely thin-barked species is susceptible to topkilling from fire. When wounded, surviving trees are highly susceptible to insects and decay. Germination is best under moist conditions and some shade, so establishment would likely occur only after low-intensity fire. Seedling establishment may occur from surviving trees onsite or from offsite seeds carried by wind.
Weather: Sweet birch is intermediate to resistant to glaze damage, but damaged crowns may provide entries for decay organisms and cause subsequent decline and death. It is intermediate in drought resistance.