Species, spacing and their interactions in four southern pines

The effect of initial spacing on plantations of loblolly pine (Pinus taeda), shortleaf pine (P. echinata), Virginia pine (P. Virginiana). and eastern white pine (P. strobus) in Tennessee is not well understood. A study of these four pines was established at the Highland Rim Forestry Field Station near Tullahoma, Tennessee. The plantation was laid out in a split plot design with the four species as main plots and four spacings as split plots. The study was measured at age 16 and total height, diameter at breast height, crown radius, height to first remaining branch, height to first live branch, percent live crown, volume per tree, basal area per tree, volume per hectare, and basal area per hectare were analyzed for all species. Number of branches per whorl nearest breast height and diameter of the largest branch in that whorl were analyzed for white pine only. Generally, the trees showed increased growth as spacing widened. Total height showed a significant effect of spacing. It was concluded that loblolly and white pine are the preferred species for planting.