Variations in Height-Over-Age Curves for Young Longleaf Pine Plantations

Abstract Some environmental factors related to height growth of longleaf pine ( Pinus palustris Mill.) plantations were identified by analyses of data from remeasured plots. A total of 660 plots, mostly from the Southwide Pine Seed Source Study, provided 2,737 height-over-age observations from age 3 through ages 15 or 20 to 22. A single variable equation derived from all observations, Log10(Height) = b 0 + b 1 (Age) -1 , was fitted to each plot. Slope coefficient (b1) from individual plots became the dependent variable for analyses to determine association of height growth patterns with recorded site and stand variables. Seventy percent of slope coefficient variation among 32 seed-source plantings was accounted for by classification of planting sites into (1) old fields, (2) mechanically prepared cutover sites, and (3) unprepared cutover sites. Among plots, coefficient values were significantly related to stand density, site quality, and seed source. Results indicate the need for a series of polymorphic plantation site-index curves, or growth models, that take into account important site-specific variables affecting early height growth. Forest Sci. 29:15-27.