Life History and Disturbance Response of Quercus stellata (post oak)
Family: Fagaceae
Guild: persistent, large-seeded, advance growth dependent
Functional Lifeform: medium-size deciduous tree
Ecological Role: found in dry woodlands on rocky or sandy, nutrient-poor soils; grows in mixtures with other xerophytic oaks and pines; very drought tolerant
Lifespan, yrs (typical/max): 250/400
Shade Tolerance: intolerant
Height, m: 15-18
Canopy Tree: yes
Pollination Agent: wind
Seeding, yrs (begins/optimal/declines): 25/50/150
Mast Frequency, yrs: 2-3
New Cohorts Source: seeds or sprouts
Flowering Dates: late spring
Flowers/Cones Damaged by Frost: yes
Seedfall Begins: early fall
Seed Banking: up to 1 yr
Cold Stratification Required: no
Seed Type/Dispersal Distance/Agent: nut (acorn)/ to 50 m/ gravity, birds, other animals
Season of Germination: fall
Seedling Rooting System: taproot
Sprouting: seedling and stump sprouts common
Establishment Seedbed Preferences:
Substrate: variable, with litter cover
Light: overstory shade
Moisture: moist required
Temperature: neutral
Disturbance response:
Fire: Post oak is well-adapted to periodic fire. If fire is infrequent or absent, post oak also is absent. Fuel type determines fire behavior and fire effects; in grassy fuels (prairie margins), fires are hotter and cause more mortality compared to fires fueled by hardwood litter. There is also more post oak mortality in trees growing near Juniperus virginiana trees, which burn intensely. In the absence of fire, trees spread and the grass dies back. If fire returns, post oaks are likely to survive because the reduction in grass fuel results in a much cooler fire. Fires in the past were mostly dormant-season fires occurring at intervals of years to decades. Post oak is a relatively thick-barked species, so most trees > 10 cm d.b.h. are moderately resistant to damage and topkill from fire. Fire-caused wounds may be entry points for damaging fungi, but post oaks are resistant to decay. Seedlings and saplings sprout vigorously when topkilled from adventitious buds in the root crown or from root suckers but trees over 25 cm d.b.h sprout poorly. Generally, because of sprouting, fires result in increased density of post oak trees. Repeated, annual fires will eventually weaken the rootstocks and kill trees. Post oak-blackjack oak forests may not revert back to savannas with prescribed burning because these forests are fire-resistant and fires are much lower in intensity in closed canopy forests than in savannas. In this situation, frequent growing season fires may be effective in reducing the density of trees because such fires are hotter than dormant season fires, and belowground carbohydrate reserves are low.
Weather: Post oak is extremely resistant to drought, and very intolerant of flooding.
Exotics: Gypsy moth (Lymantria dispar) is a defoliator of eastern hardwood forests, introduced to Massachusetts from France in 1885. It has spread throughout New England into Virginia and Michigan. Defoliation causes growth loss, decline, and mortality. It feeds on many tree species, but Quercus and Populus are the most susceptible taxa, and trees growing on xeric sites are the most vulnerable. Various efforts have been made to control it, with mixed results. A fungus, Entomophaga maimaiga introduced from Japan causes considerable mortality to gypsy moth populations. E. maimaiga levels are promoted by damp weather.