Multidecadal Response of Naturally Regenerated Southern Pine to Early Competition Control and Commercial Thinning

Multidecadal responses to early competition control are poorly documented in naturally regenerated southern pine stands. This study examined the effects of the following early herbicide treatments in thinned southern pine stands through age 31: (1) no control (CK), (2) herbaceous vegetation control only (HC), (3) woody vegetation control only (WC), and (4) total (woody herbaceous) vegetation control (TC). Previously reported (through age 13) early competition control effects on net (standing harvested) pine growth and yield were sustained from ages 15–31, where the CK treatment produced the lowest net volume growth and yield and the WC treatment generated only slightly higher and not significantly different production. Over the decades, mean tree dbh and height were consistently the greatest in the HC and TC treatments, resulting in significantly higher merchantable and sawtimber growth and yield. The pattern of growth-and-yield gains through age 31 were similar to those of other studies, including planted pine stands, indicating the importance of early competition control in the attempt to increase naturally regenerated pine production.