Differences in growth dynamics of loblolly and slash pine plantations in the southeastern United States

A species comparison study was established in 1995 in the Lower Coastal Plain of southern Georgia and northern Florida, in which loblolly and slash pine plots were paired for combinations of planting density (741–3706 trees/ha) and management intensity (operational and intensive) at nine locations. With the age 2–15 year data, species comparisons were conducted using a mixed-effect model for split-plot experiment design with repeated measurements, for average DBH, average height, average live crown length and crown ratio, cronartium infection, survival, stand density index, stand basal area and total volume. Loblolly pine consistently had greater average height and live crown length than slash pine. Average DBH did not differ between species. Loblolly pine outperformed slash pine in terms of stand basal area and total volume, partially due to the higher cronartium infection and mortality of slash pine. More intensive management significantly increased species differences in average height, stand basal area and total volume. Planting density significantly affected species difference only in live crown length.

► Growth performance of loblolly and slash pine were compared.
► Loblolly pine consistently had greater average height and live crown length than slash pine.
► Loblolly pine outperformed slash pine in terms of stand basal area and volume.
► Intensive culture increased species differences in average height, stand basal area and volume.
► Planting density significantly affected species difference only in live crown length.