Life History and Disturbance Response of Juglans nigra (black walnut)
Family: Juglandaceae
Guild: opportunistic, long-lived intolerant
Functional Lifeform: large deciduous tree
Ecological Role: grows best on deep, well-drained fertile soils and occurs as an occasional tree in mesic and dry-mesic forests; grown in plantations for highly valued wood
Lifespan, yrs (typical/max): 150/250
Shade Tolerance: intolerant
Height, m: 30-37
Canopy Tree: yes
Pollination Agent: wind
Seeding, yrs (begins/optimal/declines): 6/30/130
Mast Frequency, yrs: 2-3
New Cohorts Source: seeds or sprouts
Flowering Dates: late spring
Flowers/Cones Damaged by Frost: possible
Seedfall Begins: early fall
Seed Banking: 1 yr +
Cold Stratification Required: yes
Seed Type/Dispersal Distance/Agent: nut/ to 50 m/ gravity, other animals
Season of Germination: spring
Seedling Rooting System: taproot
Sprouting: seedling and stump sprouts common
Establishment Seedbed Preferences
Substrate: variable
Light: open areas only
Moisture: moist required
Temperature: neutral
Disturbance response::
Fire: Black walnut trees are well-adapted to periodic fire. Although most small black walnut trees are topkilled by fire, trees <20 to 30 years old will usually sprout from the root crown. Older trees usually survive the low- to moderate-intensity dormant season surface fires common in the forests where black walnut grows. These trees have thick bark and naturally durable heartwood which make them relatively resistant to damage and decay. Seedling establishment may occur from seeds of surviving trees onsite or from offsite seeds carried by water, birds, and other animals.
Weather. Black walnut is moderately tolerant of flooding. It is susceptible to late spring frosts and freezing injury when dormancy is broken in late winter warming periods.
Air pollution: Black walnut is tolerant of ozone and intermediate in sensitivity to hydrogen fluoride. No symptoms of foliar injury were noted in areas of high ambient ozone.