Simple, flexible, trigonometric taper equations

THOMAS, C. E., and PARKESOL, B. R. 1991. Simple, flexible, trigonometric taper equations. Can. J. For. Res. 21: 1132-1137. There have been numerous approaches to modeling stem form in recent decades. The majority have concentrated on the simpler coniferous bole form and have become increasingly complex mathematical expressions. Use of trigonometric equations provides a s imple expression of taper that is f lexible enough to f i t both coniferous and hardwood bole forms. As an i l lustrat ion, we applied tr igonometric taper equations to examples from thinned and unthinned slash pine (Pinus elliottii Engelm. var. elliottii), willow oak (Quercusphellos L.), and sweet gum (Liquidambar styrac$ua L.). Comparison of new tr igonometric models with a segmented-polynomial approach developed in 1976 indicates that equations based on tr igonometric functions perform equally well and have real advantages in terms of parsimony.