Immature Loblolly Pine Growth and Biomass Accumulation: Correlations with Seedlings Initial First-Order Lateral Roots

Five to seven years after being graded by first-order lateral root (FOLR) numbers and outplanted, loblolly pine (Pinus taeda L.) seedlings were excavated using a commercial tree spade and root systems re-evaluated. Current competitive position of trees was related to initial FOLR numbers of I-O seedlings. Current FOLR numbers were comparable among tree size classes, but root diameters where the spade severed the root were different. The dominant and codominant individuals had much larger FOLR cross sectional area at the severed point. The larger diameter laterals allow exploration of larger soil volume since they extended greater distances from the tree. Root biomass allometric equations were developed from excavating 175 individuals in 3 separate plantations. Root biomass was readi ly predicted based on either stem diameter breast height squared (D2H), or total aboveground biomass. Approximately 75% of standing tree biomass was aboveground and 25% belowgroundfor all initial root grades, current crown classes, and sites. Subsoil compaction layers appeared to have a major impact on tree developmentatany specijic location within a plantation. Compaction layers affected heights and diameters but not root/top ratios or the relative competition position based on initial FOLR numbers. These compaction layers resulted in plate-like taproots that suggested further root penetration was unlikely. South. .I. Appl. For. 22(2):117-123.