Life History and Disturbance Response of Platanus occidentalis (sycamore)
Family: Platanaceae
Guild: opportunistic, long-lived intermediate
Functional Lifeform: large deciduous tree
Ecological Role: common on river floodplains and sites with moist, alluvial soil; occasional pioneer on old fields and strip-mined land; replaces short-lived pioneers on river flats, but is a transitional type on drier soils
Lifespan, yrs (typical/max): 250/500
Shade Tolerance: intermediate
Height, m: 18-40
Canopy Tree: yes
Pollination Agent: wind
Seeding, yrs (begins/optimal/declines): 25/50/200
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, persistent seed balls disperse seed through the following spring
Seed Banking: up to 1 yr
Cold Stratification Required: no
Seed Type/Dispersal Distance/Agent: hairy achene/ >200 m/ wind, water
Season of Germination: spring
Seedling Rooting System: variable
Sprouting: common on young stems
Establishment Seedbed Preferences:
Substrate: variable
Light: open areas only
Moisture: moist required
Temperature: neutral
Disturbance response:
Fire: Sycamore increases with fire suppression. In bottomland hardwood communities, ground and surface fires occur frequently (5-8 years) when normal summer droughts extend into the autumn. Sycamore is unlikely to be a pioneer on burned sites, because on bottomlands, herbaceous vegetation grows rapidly and outcompetes seedlings. Uplands are probably too dry for successful sycamore establishment. Trees younger than 10 years old typically die after burning. Large trees survive most low-intensity fires but wounds may permit entry of disease. Topkilled trees sprout from adventitious buds in the root collar or from root suckers.
Weather: Although sycamore grows on moist sites, it is intolerant of flooding during the growing season. Buds are susceptible to late spring frosts. A deep-rooted species, sycamore is relatively windfirm.
Air pollution: Sycamore is tolerant to sulphur dioxide but sensitive to ozone. Symptoms of foliar injury have been noted in areas of high ambient ozone (extremely sensitive). Seedlings exhibited reduced height growth and biomass accumulation under controlled fumigation with ozone. Variable response to fumigation was noted among related individuals.