Biological growth functions describe published site index curves for Lake States timber species.

Abstract

Two biological growth functions, an exponential-monomolecular function and a simple monomolecular function, have been fit to published site index curves for 11 Lake States tree species: red, jack, and white pine, balsam fir, white and black spruce, tamarack, white-cedar, aspen, red oak, and paper birch. Both functions closely fit all published curves except those for white spruce and are recommended for use wherever mathematical functions can be conveniently used. A table of height factors is presented to simplify hand calculations of height and construction of new site index curves from these equations.