Defining the Historical Northeastern Forested Boundary of the Great Plains Grasslands in the United States

• Published in: The Professional geographer 2020-01, Vol.72 (1), p.1-8
• Main Author: Hanberry, Brice B.
• Format: Article
• Language: English
• Subjects: 19th century; Boundaries; Delineation; Encroachment; Forests; Geographic information systems; Grasslands; invasión de árboles; Palabras clave: ecotón; pradera; Remote sensing; sabana; Trees
• ISSN: 0033-0124; 1467-9272
• DOI: 10.1080/00330124.2019.1611460

The Great Plains is the grasslands of the central United States, but precise delineation of this region has evaded agreement due to the transition between Great Plains grasslands and forests of the eastern United States. After comparing Great Plains delineations in readily available geographic information system layers, I established a northeastern boundary using evidence from historical tree surveys during the 1800s. Additionally, I described tree presence within the Great Plains over time and potential drivers of change. The definition documented here diverges from others by including most of Iowa and part of Illinois, and even small sections in Indiana and Wisconsin, but excluding Missouri due to regular tree presence overall at landscape scales of ecological subsections. In this definition, the Great Plains had an extent of 2.29 million km 2 in fifteen states, including Indiana and Wisconsin, and 2.19 million km 2 after removal of open forests in Oklahoma and Texas. Tree presence occurs within the Great Plains and tree encroachment is not a new process; however, tree encroachment is increasing in the Great Plains, which causes a decrease in the grasslands region. Nevertheless, clarifying the historical eastern boundary provides a solution to the problem of competing versions of the Great Plains region. Key Words: ecotone, prairie, savanna, tree encroachment.