Effects of Herbaceous and Woody Plant Control on Longleaf Pine Growth and Understory Plant Cover

Abstract

To determine if either herbaceous or woody plants are more competitive with longleaf pine (Pinus palustris Mill.) trees, four vegetation management treatments—check, herbaceous plant control (HPC), woody plant control (WPC), and HPC+WPC—were applied in newly established longleaf pine plantings in a randomized complete block design in two studies. Prescribed fire was repeatedly applied across both study sites, and pine measurements were continued for 12 years. Pine survival was not significantly different among the four treatments in either study. In Study 1, pines were taller on HPC+WPC plots than on checks, and pine basal area and volume per ha were greater on HPC and HPC+WPC plots than on checks. Volume per ha ranged from 45 m3/ha on checks to 70 m3/ha on HPC+WPC plots. The WPC treatment was ineffective. In Study 2, there were no significant basal area and volume per ha differences among the four treatments. Volume per ha ranged from 119 m3/ha on checks to 151 m3/ha on HPC+WPC plots after 12 years. In the thirteenth growing season, HPC+WPC plots had more surface area covered in litter than did checks, and there was less grass cover on HPC plots than on checks in Study 1. In Study 2, litter and plant cover in the understory were not significantly different among the four treatments. With the application of fire, HPC remained effective when basal area per ha did not exceed 14 m2/ha. WPC was not beneficial perhaps because prescribed fire was repeatedly applied making WPC unnecessary.