Northern red oak regeneration in burned and unburned stands in the White Mountain National Forest, New Hampshire, USA, 2023-2024

This project aimed to determine whether prescribed burning of managed forest stands improves the regeneration of Quercus rubra near its northern range limit in New Hampshire. We measured oak seedling density and growth rates in three pairs of managed stands in which one had received a prescribed burn since 2017. We also measured the density of competing seedlings and shrubs, leaf area index above seedling height, soil nutrients, mycorrhizal colonization, foliar carbon/nitrogen ratio, and stable isotopes of nitrogen and carbon. We found greater oak seedling density and faster oak seedling growth rates in burned stands relative to unburned stands. A subset of these measurements were also collected in additional burned and unburned study stands in the region. A companion mesocosm experiment showed faster growth in oak seedlings grown in soil from burned vs. unburned stands. Together these studies show that the benefits of fire to oak regeneration are mediated both via greater light availability as well as effects mediated via soil.