PARENT SESSION
Oral Session # 6: Fire Ecology I: Structure and Demographics
Presiding: R Parmenter
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 105.
Fire and twenty years of change in a Carolina sandhill.
Imm, Donald*,1, McLeod, Ken2, 1 USDA-FS Savannah River, New Ellenton, SC2 Savannah River Ecology Laboratory, Aiken, SC
ABSTRACT- Sandhill woodlands are fire-prone communities with xeric, infertile sands in the southeastern coastal plain. Unlike pine savannas, fires in sandhills are less frequent due to limited litter production and varied fire behavior due to fuel quantity and presence of a hardwood mid-story. Over the past 20 years, three controlled fires and one escaped fire have occurred in the study site, dominated by few scattered longleaf pine and large oaks in the canopy and a near-continuous mid-story of turkey oak, bluejack oak, sand post oak, and other hardwoods. Based on tree cores, diameter growth of longleaf pine was reduced during the first year following summer burning but unaffected by winter burning. Oak diameter growth was reduced for 1-3 years following burning. Cumulative oak mortality increased with each successive fire. Growing season fires led to greater top kill and mortality than dormant season fires. Probability of oak mortality and top kill, both a function of size, decreased with each successive fire. Eleven dominant ground cover types were present, each with a different composition, environment, and response to burning. Dwarf huckleberry, oak-sprout, diffuse-herbaceous, and matrix-grass groundcover types increased in area following burning. Dense-herbaceous, deerberry, poison oak-mixed herbaceous, and bracken fern ground cover did not significantly change following fire. Dense litter and sparkleberry ground cover declined following fire. Immediately following fire, ground cover increased in diversity, but compositional changes were temporary (no significant difference beyond 2 years). However, with each successive burn, composition was less variable in trajectory and less resilient to return to pre-burn ground cover conditions. These results suggest that sandhill woodlands are slow to change using prescribed fire, independent of season.
Key words: fire, sandhill, vegetation change