Life History and Disturbance Response of Robinia psuedoacacia (Black Locust)
Family: Leguminosae
Guild: opportunistic, dispersal limited (sprout dependent)
Functional Lifeform: medium-sized deciduous tree
Ecological Role: nitrogen-fixing; grows best on moist, loamy soils but establishes on a variety of disturbed sites; competes well on open uplands, old fields and in large forest openings; often planted for erosion control
Mortality, yrs (typical/max): 60/100
Shade Tolerance: very intolerant
Height, m: 12-18
Canopy Tree: yes
Pollination Agent: insects
Seeding, yrs (begins/optimal/declines): 6/15/40
Mast Frequency, yrs: 1-2
New Cohorts Source: root suckers
Flowering Dates: late spring
Damaged by Frost: no
Seedfall Begins: early fall
Seed Banking: transient, 1 yr +
Cold Stratification Required: no, impermeable seed coat requires scarification
Seed Type/Dispersal Distance/Agent: pod/ to 50 m / gravity, wind
Season of Germination: spring
Seedling Rooting System: large, shallow roots
Sprouting: root suckers and stump sprouts common
Establishment Seedbed Preferences:
Substrate:variable
Light: open areas only
Moisture: moist required
Temperature: neutral
Disturbance response:
Fire: Black locust is well-adapted to periodic fire. Black locust vegetatively invades burned sites if it is present in the adjacent, unburned forest. Annual or very frequent fire probably removes black locust from the community by preventing sprouts from reaching fire-resistant size. Most fires are low-intensity; the small leaflets of black locust in the litter layer tend to lie flat and stay damp (in contrast to leaves of Quercus and Acer, which crinkle up and dry out), effectively slowing surface fires. Small trees are susceptible to topkill but sprouts rapidly from adventitious buds in the root crown or from root suckers. Black locust generally increases in density following fire, from both sprouts and new germinants. Both mowing and burning were found to be effective in reducing black locust cover; however, frequent burning may be necessary.
Weather: Black locust is moderately frost hardy. In the Appalachians, it is highly susceptible to frost damage.
Air pollution: Black locust is tolerant to sulphur dioxide and NOx ., and intermediate in sensitivity to hydrogen fluoride. It is sensitive to ozone. Symptoms of foliar injury have been noted in some areas of high ambient ozone, but not in others (slightly sensitive); no foliar injury was observed after fumigation with ozone. No observed difference in height was noted in seedlings fumigated with ozone under controlled conditions.