The effect of spacing rectangularity on stem quality in loblolly pine plantations

The effect of spacing rectangularity on tree stem quality was evaluated using data collected from a loblolly pine (Pinus taeda L.) spacing trial measured at age 19. In this trial, bole condition, branch size, and stem asymmetry were examined on plots with an initial planting density of 2240 trees/ha planted at slight (3:4) and greater (1:3) rectangular spacings to determine suitability for sawtimber production. Results indicated that rectangularity had no significant effect on survival or the number of potential sawtimber trees by age 19. While the 1:3 spacing treatment had a significantly larger maximum branch size than the 3:4 spacing treatment, it could not be attributed to the within-row or between-row direction. Additional measurements on stem diameter at breast height within and between rows failed to show stem asymmetry in the 1:3 spacing treatment. Consequently, rectangular spacings up to 1:3 should not have much impact on overall stem quality.