The effects of fertilization and competition control on loblolly pine fine root dynamics

Abstract

We studied the effects of annual fertilization (F) and complete competition control via herbicides (H) on fine root dynamics in 13yr. old Pinus taeda stands. We measured fine root length, mass, and production. Relative to the control, both F and H decreased fine root length and mass. The single-factor effects were greatest for H, which reduced both root mass and length by half. In combination (HF) fine root mass was reduced by 66%. With respect to above vs. below ground mass, both F and H increased the amount of leaf area supported per unit root mass and length. Their combined effects (HF) were nearly additive. Relative to control, all treatments decreased root production and show apparent increases in root longevity. The results suggest that both fertilization and herbicides alter patterns of allocation, and that in combination they produce nearly additive effects with respect to increasing wood production per unit of root length or mass.