American Elm Site-Index Growth Curves

Abstract

Site-index curves for evaluating the growth potential of American elm in native timber stands in Kansas were developed from data gathered in the 1964-1965 Kansas forest inventory. American elm (Ulmus americana L.) is the most common native elm found in Kansas. The wood is used principally for agricultural implements, barrels, furniture, and pallets (Stephens, 1969). It grows best on better drained, rich bottomland soils, and in the western portion of its range, it occurs along watercourses with boxelder, green ash, and cottonwood (Harlow and Harrar, 1950). American elm can be found on nearly all soil types within its range (Fowells, 1965). It ranks third in total standing biomass in Kansas and is harvested extensively, but experiences very high natural mortality from Dutch elm disease (Raile and Spencer, 1984). Evaluation of site productivity (wood-producing potential of an area) is an important aspect of management for attaining maximum benefits from forest lands. The site-index method is the most widely accepted means for determining site quality. It uses tree height/age relationships, which correlate well with timber yields. By definition, site index is the average height at age 50 years of dominant/codominant (overstory) trees in a fully stocked, evenaged stand. Curves or tables have been published for many commercial tree species in the United States (Carmean et al., 1989). Site quality is best determined by local site index curves. In Kansas, only curves for black walnut (Juglans nigra L.), hackberry (Celtis occidentalis L.), and green ash (Fraxinus pennsylvanica L.) have been published (Geyer and Lynch, 1987; Lynch and Geyer, 1988; and Geyer and Lynch, 1990, respectively). The purpose of this paper is to provide another in a series of site-index equations, curves, and height tables for important tree species growing in natural stands in Kansas.