A Stocking Diagram for Midwestern Eastern Cottonwood-Silver Maple-American Sycamore Bottomland Forests

A stocking diagram for Midwestern bottomland eastern cottonwood (Populus deltoides Bartram ex Marsh.)-silver maple (Acer saccharinum L.)-American sycamore (Platanus occidentalis L.) forests was developed following the methods of S.F. Gingrich (1967. Measuring and evaluating stocking and stand density in upland hardwood forests in the Central States. For. Sci. 13:38–53). The stocking diagram was derived from forest inventory data from two different studies of bottomland forests that covered a wide range of soil and hydrologic site characteristics found throughout the central Midwest, including Missouri, Iowa, Illinois, and southern Wisconsin. The minimum of full stocking (B-level) was determined from measurements on open-grown trees. The maximum of full stocking (A-level) in our study was almost one-third higher in stand basal area than A-level stocking, as determined by J.C.G. Goelz (1995. A stocking guide for southern bottomland hardwoods. South. J. Appl. For. 19:103–104) for southern hardwood bottomlands dominated by cherrybark oak (Quercus pagoda Raf.), Nuttall oak (Quercus nuttallii Palmer), and sweetgum (Liquidambar styraciflua L.,), or by C.C. Myers and R.G. Buchman (1984. Manager’s handbook for elm-ash-cottonwood in the north central states. GTR-98. US Forest Service, North Central For. Exp. Stn., St. Paul, MN. 11 p) for elm (Ulmus spp.), ash (Fraxinus spp.), and eastern cottonwood forests in the north central states. However, A-level stocking in this study was only slightly higher than guides developed for northern red oak (Quercus rubra L.) in Wisconsin (McGill, D.W., R. Rogers, A.J. Martin, and P.S. Johnson. 1999. Measuring stocking in northern red oak stands in Wisconsin. North. J. Appl. For. 16:144–150). Differences in stocking among these forest types are due to variation in species composition, species silvical characteristics, and possibly the data sources used to construct the stocking diagrams. This stocking diagram can be used by forest managers to make decisions related to stand stocking for management of eastern cottonwood, silver maple, and American sycamore bottomland forests in the Midwest.