Abstract
Direct seeding of southern pines is an effective method of artificial regeneration, producing extremely dense stands when survival exceeds expectations. Long-term studies of dense direct-seeded stands provide ideal data for exploring development of stands as they approach the limit of maximum stand density. I present data from seven studies with ages of stands ranging from 11 to 42 years. Reineke's relationship serves as the paradigm of stand density. A weighted regression estimated the limiting density line for loblolly (
Pinus taeda L.) and longleaf pines (
Pinus palustris Mill.). The slope was common for both species, but the intercept varied, providing a maximum stand density index for loblolly pine that was roughly 9 percent greater than that for longleaf pine. I fit simple response surfaces for mortality, growth of basal area, volume, and weight to explore how these processes changed with stand density. Stand density did not affect mortality of longleaf pine, allowing stand stagnation as diameter growth decreased greatly. However, dynamics of loblolly pine included significant density-dependent mortality when stand density was > 50 percent of maximum. For basal area growth, both species had maximal growth at or below 50 percent of maximum stand density. For volume growth of loblolly pine, maximal growth occurred near 50 percent of maximum stand density. For volume growth of longleaf pine and weight growth of both species, maximal growth occurred at or near maximal stand density.
Parent Publication
Citation
Goelz, J.C.G. 2006. Dynamics of dense direct-seeded stands of southern pines. Gen. Tech. Rep. SRS-92. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. pp. 310-316