The Plantation Conversion Demonstration at the Crossett Experimental Forest--Implications For Converting Stands From Even-Aged to Uneven-Aged Structure

In the absence of replicated studies, we used a case study demonstration to illustrate converting a 26-year-old even-aged loblolly pine (Pinus taeda L.) plantation to uneven-aged structure. Unreplicated treatments included maintaining even-aged structure through low thinning (thinning from below) to a residual basal area of 80 square feet per acre, and two methods of converting to uneven-aged structure-one using the volume control guiding diameter limit method, and the other using the BDq method of structural regulation. Over 12 years, all three treatments had a periodic annual increment of over 90 square feet per acre in both total merchantable and sawtimber cubic volume; all three treatments also maintained annual sawtimber volume growth rates of 90-100 square feet per acre, 450-600 board feet per acre Doyle rule, and 600-750 board feet per acre International 1⁄4-inch rule. In all volume increment measurements, the even-aged treatment exceeded the volume control method, which exceeded the BDq method. Conversely, the BDq method was the only treatment in which adequate pine regeneration was established and making acceptable development; regeneration development in the volume control treatment was marginal, and it was unacceptable in the even-aged treatment. After 12 years, residual basal area levels exceeded 60, 75, and 100 square feet per acre in the BDq, volume control, and even-aged treatments, respectively. To increase the reliable development of regeneration in these treatments, lower residual basal areas should be considered. 1Research Forest Ecologist and Project Leader, Monticello-Crossett Forestry Sciences Laboratory, Southern Research Station, USDA Forest Service, Monticello, AR.; Forestry Consultant, 880 Old West Point Road, Starkville, MS, respectively. Citation for proceedings: Outcalt, Kenneth W., ed. 2002. Proceedings of the eleventh biennial southern silvicultural research conference. Gen. Tech. Rep. SRS–48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 622 p.