Bedding of wetland soil: Effects of bed height and termite activity on wood decomposition
Microorganisms and termites are the primary wood decay agents in forests of the southeastern United States, whose activity can be affected by forest management practices. Bedding establishes raised planting beds on poorly-drained soils, but little is known about the effect of bedding or soil bed height on wood decomposition. Therefore, a four height bedding study was conducted on a wetland soil in eastern South Carolina: flat (no bedding), half (7.5 cm), single (20 cm), and double (30 cm) above the original soil surface. Aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.) wood stakes were inserted to 30-cm soil depth, sampled over 23 mo, and decomposition (mass loss) by soil microorganisms and termites assessed. Microbial decay of both aspen and pine stakes increased as bed height increased, approaching 50% mass loss in double beds at the end of the study. Termites were not present in the flat (unbedded) soil, only damaged <1% of stakes in half beds, but were very active in single and double beds. Termites damaged or consumed 43% of aspen stakes in the double beds, which increased aspen mass loss by 30%. In contrast, termites attacked only 11% of pine stakes in double beds, and had little impact on mass loss. Stake decomposition was highest at the 5-cm soil depth and was affected by soil microsite variability among soil bed heights. Soil bedding increased wood decomposition by both soil microorganisms and termites, and their impact on soil organic matter content and productivity deserves more attention.