Development of Planting Density-Specific Density Management Diagrams for Loblolly Pine

For density management diagrams (DMDs), it is usually assumed the relative value between Reineke’s stand density index (SDI) where self-thinning is expected to begin and a maximum size-density relationship species boundary line is constant regardless of planting density. Using estimated size-density trajectories of loblolly pine plantations in the southeastern United States, the quadratic mean diameter at which the onset of self-thinning occurs was determined. An equation was then fitted to estimate the quadratic mean diameter at which self-thinning is expected to begin relative to planting density. DMDs that accounted for planting density showed that self-thinning began at 40 –72% of the species maximum SDI for planting densities ranging from 605 to 2,722 seedlings per acre.