Title: Modifying Taper-Derived Merchantable Height Estimates to Account for Tree Characteristics

Author: Westfall, James A.

Year: 2006

Publication: In: Proceedings of the sixth annual forest inventory and analysis symposium; 2004 September 21-24; Denver, CO. Gen. Tech. Rep. WO-70. Washington, DC: U.S. Department of Agriculture Forest Service. 126p.

Abstract: The U.S. Department of Agriculture Forest Service Northeastern Forest Inventory and Analysis program (NE-FIA) is developing regionwide tree-taper equations. Unlike most previous work on modeling tree form, this effort necessarily includes a wide array of tree species. For some species, branching patterns can produce undesirable tree form that reduces the merchantable portion of the stem and merchantable heights to a fixed top diameter (e.g., 4 inches) are often unrealized. Thus, height estimates from a taper model tend to overestimate the actual merchantable length of the stem. This phenomenon is exacerbated as tree size increases. The extent of this problem is illustrated by comparing taper-derived merchantable height estimates to observed merchantable height measurements on trees from NE-FIA sample plots. Models were developed using individual tree attributes to adjust the taper-based estimates to account for reductions in merchantable height due to tree form.