The highly dynamic, fine root component of forested wetland ecosystems has
recieved inadequate attention in the literature. Characterizing fine root dynamics
is a challenging endeavor in any system, but the difficulties are particularly
evident in forested floodplains where frequent hydrologic fluctuations directly
influence fine root dynamics. Fine root (=<3 mm) biomass, production, and
turnover were estimated for three soils exhibiting different drainage patterns
within a mixed-oak community on the Coosawatchie River floodplain, Jasper County,
South Carolina. Within a 45-cm-deep vertical profile, 74% of total fine root
biomass was restricted to the upper 15 cm of the soil surface. Fine root biomass
decreased as the soil became less well drained (e.g., fine root biomass in well-drained
soil > intermediately drained soil > poorly drained soil). Fine root productivity
was measured for 1 yr using minirhizotrons and in situ screens. Both methods
suggested higher fine root production in better drained soils but showed frequent
fluctuations in fine root growth and mortality, suggesting the need for frequent
sampling at short intervals (e.g., monthly) to accurately assess fine root growth
and turnover. Fine root production, estimated with in situ screens, was 1.5,
1.8, and 0.9 Mg ha-1 yr-1 in the well-drained, intermediately drained, and poorly
drained soils, respectively. Results from minirhizotrons indicated that fine
roots in well-drained soils grew to greater depths while fine roots in poorly
drained soils were restricted to surface soils. Minirhizotrons also revealed
that the distribution of fine roots among morphological classes changed between
well-drained and poorly drained soils.