–Site index curves for loblolly pine at index age 25 years in the coastal plain of Virginia, North Carolina, and South Carolina. (These curves are based stem analysis of 40 dominant trees in the middle and lower Coastal Plain.)

Seventy-four permanent growth plots in another study were provided independent data for testing our new site index curves with those of Schumacher and Coile (1960). We chose the Chumacher-Coile curves for purposes of comparison because they are widely used in estimating growth and yield of loblolly pin in the Southeastern Coastal Plain. When the growth plots were established in 1949, they ranged in age from 16 to 50 years and in site index (age 50) from 63 to 119 feet. Measurements of these 74 plots at 5-year intervals for 20-year period furnished 364 separate estimates of age and height.

Reproduced from USDA For. Ser. Res. Paper SE-115, June 1974.