Date of Award

Spring 2025

Project Type

Thesis

Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

Heidi HA Asbjornsen

Second Advisor

Erin EL Lane

Abstract

Northern red oak (Quercus rubra) is predicted to expand its range northward in the northeastern United States with climate change and could greatly improve resilience of managed forests by expanding the functional diversity. However, red oak regeneration across its range currently faces many challenges including predation, pathogens, and consequences of forest mesophication such as insufficient light and competition with more mesic species. The latter challenges are potentially caused by the near absence of fire in most northeastern forested landscapes since the early 1900s. Therefore, prescribed burns may help address these challenges and hence promote oak recruitment and establishment. We studied six prescribed burn/unburn pairs of stands from across the White Mountain National Forest in New Hampshire, USA, most of which were managed over the past decade, plus one unmanaged stand where a wildfire occurred. In summers 2023 and 2024, we surveyed naturally regenerated oak seedlings along transects representing gradients of burn intensity, distance from edge, overstory density, and soil disturbance. Seedlings were aged, measured for height and diameter at root collar, and assessed for herbivory and pathogen damage. We found seedling density to be almost three times greater in prescribed burn stands relative to paired unburned stands. Seedlings in burned stands also grew better, evidenced by greater diameter at root collar, greater extension growth, and more leaves. Our study demonstrates positive effects of prescribed burns in recently harvested stands for red oak regeneration near its northern range limit and affirms prescribed fire as a potentially beneficial silvicultural management tool in introducing the species north of its current distribution.

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