Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands—II. Development of Intermediate and Suppressed Trees Following Release in Natural Stands

Abstract

Abstract Development of 86 intermediate and suppressed loblolly pine (Pinus taeda L.) trees, that had been recently released from overtopping pines and hardwoods, was monitored over a 15 yr period. The trees were growing in natural stands on good sites (site index = 90 ft at 50 yr) that had been recently cut to stocking levels ranging from 10 to 50%. At time of release, the trees averaged 26 yr in age, 4.8 in. in dbh, and 37 ft in height. The trees had averaged only 0.5 in. in dbh growth the 5 yr prior to release (0.1 in./yr). After 15 yr, the 77 surviving trees averaged 59 ft in height and 12.9 in. in dbh, increasing 21 ft in height and 8.1 in. in dbh. During the 15 yr period, crown dimensions of the trees increased markedly as well. On average, crown lengths increased 11 ft (from 16 to 27 ft); crown widths nearly tripled from 9 to 25 ft; and crown volumes increased 11 fold from 608 to 6,700 ft³. The majority of the trees had good form and would produce high-quality sawtimber. Satisfactory response to release was best predicted by initial dbh and live-crown ratio. Results of the study suggest that trees with at least a 20% live-crown ratio should satisfactorily respond to release even though they had developed in lower crown positions of fully stocked uneven-aged stands for 10 to 50 yr. Responding trees rapidly expanded their crowns and accelerated in height and diameter growth. South. J. Appl. For. 22(1):41-46.