An improved growth intercept method for estimating site index of red pine.

Equations for predicting red pine (Pinus resinosa Ait.) site index from various internode lengths were developed from ring counts on sectioned trees form 69 natural stands in Minnesota. The precision of estimating site index was much improved by measuring the 5-year growth intercept beginning at 7 feet above the ground rather than at the conventional breast height. The growth intercept equation developed from natural stands in Minnesota is shown to be applicable to red pine plantations in Minnesota, New York, and Connecticut.