Overstory tree status following thinning and burning treatments in mixed pine-hardwood stands on the William B. Bankhead National Forest, AlabamaThis article is part of a larger document. View the larger document here.
Prescribed burning and thinning are intermediate stand treatments whose consequences when applied in mixed pine-hardwood stands are unknown. The William B. Bankhead National Forest in northcentral Alabama has undertaken these two options to move unmanaged, 20- to 50-year-old loblolly pine (Pinus taeda L.) plantations towards upland hardwood-dominated stands. Our study of their management employs a randomized complete block design with a three by three factorial treatment arrangement and four replications of each treatment. Treatments are three residual basal areas (50 square feet per acre, 75 square feet per acre, and an untreated control) with three burn frequencies (frequent burns once every 3 to 5 years, infrequent burns once every 8 to 10 years, and an unburned control). To date, only one burn cycle has been completed (all burn units burned once). Stands were thinned from June through December, and burned in December through March. We measured the overstory response to these treatments 1 year after implementation. Pretreatment basal area ranged between 952 and 163 square feet per acre; harvesting reduced basal areas to 51 square feet per acre and 68 square feet per acre in the 50 and 75 retention treatments, respectively. The percentage of total basal area that was loblolly pine remained relatively unchanged posttreatment (47.4 percent pretreatment and 46.5 percent posttreatment). Oak basal area (Quercus alba L., Q. prinus L., Q. falcata Michx., Q. rubra L., Q. velutina Lam., and Q. coccinea Münchh.) increased slightly posttreatment, from 7 percent of total stand basal area to 10 percent. Harvested stands had a 30-percent reduction in percent canopy cover, and light penetration through the canopies ranged from 5 to 25 percent pretreatment to 29 to 60 percent posttreatment. The cool, slow moving burns had no discernible effect on the overstory trees.