Development of Loblolly Pine in Dense Stands

Abstract Growth of loblolly pine ( Pinus taeda L.) was observed from annual measurements on twenty 0.04-ha plots in the Lower Coastal Plain of South Carolina through ages 3 to 14 years. Stand density classes at age 3 were 2,500, 5,000, 10,000, 20,000, and 40,000 stems per ha. Mortality rate varied directly with density. The 40M and 20M plots were approaching a common, lower density by age 10. At 14 years, average d.b.h. varied from 11.4 cm on the 2.5M plots to 6.6 cm on the 40M plots, and average heights from 11.1 m to 9.6 m. Basal area at all ages increased with increasing density to a maximum on the 40M plots. Total stand stemwood volumes at age 10 increased as surviving density increased from 2,200 to 8,000 stems on the 2.5M, 5M, and 10M plots and then leveled off to form a plateau of essentially constant yield over a density range from 8,000 to 18,000 trees per ha on the 10M, 20M, and 40M plots. The plateau was a consequence of reduced stand height at high densities combined with a curvilinear increase in basal area. The yield plateau was still apparent at age 14, when the average plateau volume was 143 cubic meters per ha. Aboveground stand dry matter at age 14 varied from 63,000 kilograms per ha on the 2.5M plots to a level yield of 85,000 to 87,000 kilograms on the 10M to 40M plots. Forest Sci. 22:331-337.