Planting density effects on growth and survival of four pine species after 22 and 30 years on the eastern Highland Rim, TN

Pinus taeda L. (loblolly pine), P. Virginiana Mill. (Virginia pine), P. echinata Mill, (shortleaf pine), and P. strobus L. (eastern white pine) were planted in two acre split plots at 6x6 foot spacings, 9x9 foot spacings, 12x12 foot spacings and 15x15 foot spacings on the eastern Highland Rim of Tennessee in 1965. The site was converted from hardwoods following a clearcut, injection of 2,4,5-T on cull trees and a prescribed burned. Height and diameter were measured at ages 22 and 30. Survival, tree dimensions (height, diameter, individual tree volume, and value per tree) and stand dimensions (basal area per acre, volume per acre and value per acre) were compared among spacings, species and for the combined affects of species and spacing on these parameters. By age 22, competition at the closest spacing had begun to decrease survival. Planting density had no consistent impact on height growth but diameter growth increased with each increase in initial spacing. Stand dimensions decreased as spacing increased. White pine and loblolly pine grew better on this site than shortleaf pine and Virginia pine. At 22 and 30 years, loblolly pine and white pine planted at a 6x6 foot spacing and followed closely by white pine at a 9x9 foot spacing had higher volumes than any species at all spacings. The greatest merchantable volume as expressed as a value per acre was achieved by white pine at the 9x9 foot spacing followed by white pine at all other spacings.