Fine root productivity and dynamics on a forested floodplain in South Carolina

The highly dynamic, fine root component of forested wetland ecosystems has received inadequate attention in the Literature. Characterizing fine root d ynamics is a challenging endeavor in any system, but the difficulties are p articularly evident in forested floodplains where frequent hydrologic fluct uations directly influence fine root dynamics, Fine root (less than or equa l to3 mm) biomass, production, and turnover were estimated For three soils exhibiting different drainage patterns within a mixed-oak community on the Coosawhatchie 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 soi l 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 method s suggested higher fine root production in better drained soils but showed Frequent fluctuations in fine root growth and mortality, suggesting the nee d for frequent sampling at short intervals (e,g,, monthly) to accurately as sess 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 Fro m minirhizotrons indicated that fine roots in well-drained soils grew to gr eater depths while fine roots in poorly drained soils were restricted to su rface soils. Minirhizotrons also revealed that the distribution of fine roo ts among morphological classes changed between well-drained and poorly drai ned soils.