Current and Historical Composition and Size Structure of Upland Forests Across a Soil Fertility Gradient in North Mississippi
Sherry B. Surrette, Steven M. Aquilani, and J. Stephen Brewer
Department of Biology
University of Mississippi
University, Mississippi 38677-1848
USA
Correspondence: Stephen Brewer
jbrewer@olemiss.edu
ABSTRACT - Comparisons of current and historical tree species composition and size structure along natural soil fertility gradients are useful for inferring effects of disturbance regimes and soil fertility on patterns of succession. We tabulated occurrences and estimated diameters of 3,483 GLO witness trees across 19 survey townships along an upland soil fertility gradient in north Mississippi. We then contrasted this presettlement composition and structure with that of 2,998 trees in sampling plots within present-day mature (>100 years) upland forests contained within the survey townships. Presettlement upland communities consisted of non-successional communities dominated by shade-intolerant, fire-tolerant trees (e.g., Quercus marilandica) in both the overstory and midstory across the entire soil fertility gradient. These fire-prone presettlement assemblages differed greatly from present-day mature uplands, which were transitional assemblages of upland and floodplain trees, with mesophytic floodplain species (both early- and late-successional) dominating the midstory and understory.