Current and presettlement tree species composition of some upland forests in northern Mississippi

BREWER, J. S. (Department of Biology, P O. Box 1848, University, MS, 38677-1848). Current and Presettlement Tree Species Composition of Some Upland Forests in Northern Mississippi. J. Torrey But. Soc. 128:332349. 2001.-Combining the study of changes in mature forests with the study of secondary succession provides a unique opportunity to understand forests in a way not made possible by studying each alone. In this study. I examined tree species composition of two mature (>150 yr-old) upland hardwood forests with a long history of fire suppression and two younger second-growth upland forests (40 yr-old), also fire-suppressed. I then compared present-day tree species composition of the two old-growth forests and the two younger forests with the composition of bearing trees (i.e., trees identified by land surveyors in the 1830s) in upland and lowland areas within townships encompassing the four sites. Bearing tree samples were similar in composition to an explorer's account of old-growth woodlands that dominated the region during sparse subsistence settlement by Chickasaw Indians. There were striking differences between present-day and bearing-tree samples. One of the old-growth forests (Bailey Woods) was more similar in species composition to the mid-successional second-growth forests than to bearing-tree samples. The shade-intolerant, but fire-tolerant, Quercus marilandica Muenchh. was nearly absent from present-day upland forests (< 1% of all sterns greater than or equal to 10 cm dbh: range 0-3%) but was the most common species among presettlement upland trees (42% of all hearing trees in the township containing the field sites). Liquidambar styraciflua L., often regarded as both a pioneer species and a common constituent of alluvial floodplain and mesophytic terrace forests, was the single most abundant tree species in the understory and midcanopy of one of the old-growth forests (Bailey Woods) and in all size classes of trees of both younger forests. It was completely absent from presettlement records of upland trees, but was an abundant bearing tree in nearby sections containing lowland alluvial forests. I hypothesize that open oak woodlands dominated the upland landscape of Lafayette County, Mississippi before extensive settlement. These woodlands were neither mid-successional nor late-successional forests but were a unique fire-dependent community type that is absent from north Mississippi today.