Life History & Disturbance Response of Tilia americana American basswood
Guild: persistent, slow-growing understory tolerant
Functional Lifeform: large deciduous tree
Ecological Role: grows best on mesic sites but
is also found on coarse soils and exposed ridges; occurs with sugar maple
in the upper midwest and is a minor component of hardwood mixtures in the
Lifespan, yrs (typical/max): 100/140
Shade Tolerance: tolerant
Height, m: 23-40
Canopy Tree: yes
Pollination Agent: insects
Seeding, yrs (begins/optimal/declines): 15/15/100
Mast Frequency, yrs: 1-2
New Cohorts Source: seeds or sprouts
Flowering Dates: early summer
Flowers/Cones Damaged by Frost: no
Seedfall Begins: early fall
Seed Banking: 1 yr +
Cold Stratification Required: yes
Seed Type/Dispersal Distance/Agent: nutlike drupe/
to 50 m/ gravity, birds
Season of Germination: spring
Seedling Rooting System: taproot
Sprouting: common, large and small stems sprout
Establishment Seedbed Preferences
Light: overstory shade
Moisture: moist required
Fire: American basswood is most common in forests
with fire intervals of several decades to centuries. This species, along
with some maple species, spreads where fire is suppressed, thus are replacing
species favored by periodic fire (e.g., Quercus). American basswood
is also encroaching onto former grasslands since fires have been suppressed.
Once established, Acer-Tilia forests do not burn easily. Although
it is thin-barked, basswood is somewhat resistant to low-intensity fire,
and sprouts readily from the root crown or from root suckers when topkilled.
Fire-damaged American basswood trees are susceptible to butt rot. Moderate-intensity
fires actually favor American basswood density by creating light conditions
that favor American basswood sprouts over Acer saccharum seedlings.
American basswood sprouts are less abundant at long fire intervals, presumably
because heavy shade in very dense stands is not tolerated by American basswood
reproduction. Prescribed burning may be useful for encouraging good-quality
sprouts in harvested American basswood stands, because post-fire sprouts
occur lower on the stump and consequently develop less butt rot.
Weather: American basswood is extremely tolerant
of late-spring frosts.
Air pollution: American basswood is intermediate
in sensitivity to sulphur dioxide, but tolerant to ozone and hydrogen fluoride.