Effects of herbaceous and woody plant control on Pinus palustris growth and foliar nutrients through six growing seasons

To determine if either herbaceous or woody plants are more competitive with longleaf pine (Pinus palustris P. Mill.) seedlings, two vegetation management treatments-herbaceous plant control (HPC, No or Yes) and woody plant control (WPC, No or Yes) were applied in newly established longleaf pine plantings in a randomized complete block 2 × 2 factorial design in two studies (α = 0.05). Both studies were broadcast prescribed burned as a normal management practice and the soils were of moderate texture. In the fourth growing season and 2 years after treatments ceased in Study 1, the HPC plots had more herbaceous plant productivity than the no HPC (NHPC) plots and arborescent vegetation had recovered from the WPC treatment. In Study 2, herbaceous plant productivity was less on the HPC plots than on the NHPC plots and the WPC plots had more herbaceous plant productivity and less arborescent vegetation than the no WPC plots. In both studies, HPC significantly increased height growth of the longleaf pine trees although total control of herbaceous plants was neither attempted nor achieved. The WPC treatment did not affect longleaf pine height growth. After six growing seasons, the longleaf pine trees averaged 0.9, 1.5, 1.1, and 1.7 m tall on the Burn only, Burn-HPC, Burn-WPC, and Burn-WPC-HPC treatments, respectively, in Study 1. In Study 2, the longleaf pines averaged 3.8, 4.8, 3.9, and 4.8 m tall on the Burn only, Burn-HPC, Burn-WPC, and Burn-WPC-HPC treatments, respectively. Herbaceous plant control reduced Mg concentrations in the living longleaf pine needles in both studies. Foliar P was generally deficient. Overall, however, the longleaf pine foliage had good nutritional balance on these moderately textured soils.