Acorn viability following prescribed fire in upland hardwood forests

The fire—oak literature of eastern North America: synthesis and guidelines

“…These temperatures did not cause death to buried acorns or roots in the soil. Greenberg et al (2012) found that after a low-intensity dormant season fire, germination rates for white oak and northern red oak acorns were lower for seed located on the litter surface compared to those in the duff-mineral soil interface or buried in 2 inches of mineral soil.…”

“…Korstian surmised that this gradient was caused by the differences in germination timing (autumn for white oaks, spring for red oaks) between the two groups. Subsequent research has confirmed that acorns are easily killed by fires (Auchmoody and Smith 1993, Dey and Fan 2009, Greenberg et al 2012.…”

“…However, longer exposure to lower temperatures may also cause the death of tissue. Average maximum temperatures from 174 to 700 o F have been recorded at or near the ground during prescribed fires in hardwood forests in the Missouri Ozarks (Dey and Hartman 2005), Ohio (Hutchinson et al 2005a, Iverson et al 2004, Phillips et al 2007, and the southern Appalachian Mountains (Elliott and Vose 2005, Greenberg et al 2012, Phillips et al 2007). These temperatures are capable of causing death to hardwood stems depending on duration of exposure and tree characteristics.…”

“…Auchmoody and Smith (1993) observed that a low intensity fire killed nearly half of the northern red oak acorns in the litter. Greenberg et al (2012) reported that after a low intensity fire, white oak and northern red oak acorns in the litter that were subjected to 400 o F had high rates of mortality, and all acorns perished when temperatures were above 500 o F. Additionally, surviving acorns often produce low-vigor seedlings (Auchmoody andSmith 1993, Dey andFan 2009). …”

Fire in upper Midwestern oak forest ecosystems: an oak forest restoration and management handbook

“…Greenberg et al (2012) do not allow fires to take place with very low-humidity and high-wind conditions during severe droughts-conditions during which natural fires made their large runs with high intensities likely to kill species that compete with oaks. Although they would have had immediate negative effects on oaks, oaks were more poised to regrow vigorously in such postfire conditions.…”