Fuel reduction treatments affect stand structure of hardwood forests in Western North Carolina and Southern Ohio, USA

Prescribed fire and mechanical treatments were tested at the two hardwood sites of the National Fire and Fire Surrogate Study (southern and central Appalachian regions) for impacts to stand structure. After two fires and one mechanical treatment, no treatment or treatment combination restored stand structure to historical levels. Burning alone had little impact on overstory vegetation the first year after treatment but mortality continued for 4–5 years thus opening canopies. Thinning at the Ohio Hills site reduced stand basal area, but not to levels desired for restoration objectives. Chainsaw removal of the shrub layer at the southern Appalachian site reduced the midstory temporarily but promoted abundant regeneration. The combination of mechanical and burning treatments opened these dense forests the most, especially at the southern Appalachian site where hot fires killed overstory trees and promoted oak regeneration. Results from both study sites emphasize the rapid sprouting and growth of undesirable eastern species and the need for frequently-repeated treatments during the restoration phase.