Presettlement vegetation patterns, 5th principal meridian, Missouri Territory, 1815 Nelson, J. C. 1997. Presettlement vegetation patterns along the 5th principal meridian, Missouri Territory, 1815. American Midland Naturalist 137:79 94. Reprinted by U.S. Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, November 1997. LTRMP 97-R026. 16 pp. (NTIS #PB98-113152) ABSTRACT Data from the original General Land Office (GLO) survey (1815) of the 5th Principal Meridian were used to evaluate presettlement vegetation patterns in eastern Missouri and Arkansas. Data were divided into three physiographic sections: Mississippi Alluvial Plain, Ozark Plateau, and Dissected Till Plain. Distances to bearing trees and diameters were used to estimate tree density and to evaluate the relative structure and composition of presettlement vegetation. The Mississippi Alluvial Plain was the most densely timbered physiographic section. White oak (Quercus alba), black oak (Q. velutina), sweet gum (Liquidambar styraciflua), and hickory (Carya spp.) had high importance values. Significantly lower tree densities occurred in the Ozark Plateau and Dissected Till Plain. Important components of the Ozark Plateau were shortleaf pine (Pinus echinata), white oak, black oak, and post oak (Q. Stellata). In the Dissected Till Plain, white oak was dominant and black oak, hickory, elm (Ulmus spp.), and sycamore (Platanus occidentalis) were important components. There has been some debate regarding the presettlement structure of timbered lands in the Ozark Plateau. Some biologists argue that closed forest once dominated the Ozarks, whereas others argue the region was once dominated by open woodland. The evidence presented here suggests the Ozark vegetation was, in general, an open woodland landscape in 1815. KEYWORDS Disturbance, floodplain, Mississippi River, Ozarks, prairie, presettlement, restoration, savanna, woodland