Wood decomposition in poorly-drained forested wetland soils: How important are termites?

Authors: ADAMS, M.B. - Us Forest Service (FS); MILLER, C. - Us Forest Service (FS); McCarty, Gregory; LANG, M.W. - Us Fish And Wildlife Service; STRANO, S. - Maryland Department Of Natural Resources; RIZZO, A. - Natural Resources Conservation Service (NRCS, USDA); PAGE-DUMROESE, D.S. - Us Forest Service (FS); JURGENSEN, M.F. - Us Forest Service (FS)

Submitted to: Journal of Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2025
Publication Date: 2/18/2025
Citation: Adams, M., Miller, C., Mccarty, G.W., Lang, M., Strano, S., Rizzo, A., Page-Dumroese, D., Jurgensen, M. 2025. Wood decomposition in poorly-drained forested wetland soils: How important are termites?. Journal of Soil Biology and Biochemistry. 204. https://doi.org/10.1016/j.soilbio.2025.109754.
DOI: https://doi.org/10.1016/j.soilbio.2025.109754

Interpretive Summary: The rate of wood decomposition in wetland ecosystems is an important parameter for understanding the ability of these ecosystems to store carbon. This study measured the influence of the average number of days in a year that the wetland is saturated (wetland hydroperiod) on the rate of wood decomposition. Results showed that the termite activity involved in wood decomposition decreased substantially with increase in hydroperiod of the ecosystem. The information gained from this study will inform models assessing ecosystem carbon storage and improve global estimates of carbon sequestration by wetlands.

Technical Abstract: Forested wetlands provide important ecosystem functions, including storing carbon. However, the decomposition of wood in freshwater forest wetlands has been understudied, especially in the mineral soil. Therefore, we established a 5-year study to assess the effect of forested wetland soil hydrology on wood decomposition in a restored wetland and an adjacent upland site located on the eastern shore of Maryland, USA. Aspen (Populus tremuloides Michx.), red maple (Acer rubrum L.) and loblolly pine (Pinus taeda L.) were placed horizontally on the surface of the litter layer and at the interface between the litter layer and mineral soil, and vertically into the mineral soil. Stakes were sampled annually for 5 years and separated in the laboratory by the presence of termite attack for subsequent statistical analyses. In the wettest sites, those with a seasonal water table at or above the surface, decomposition was slow, with the highest decomposition rates occurring on the surface of the litter layer and decreasing with increasing soil depth. Water table depth had a greater effect on wood decomposition by termites than that by microbial decay, but stake mass loss was often limited by fluctuating water table depth. Small differences in surface elevation on this wetland soil had a major impact on wood decomposition, especially by termites. Decomposition of stakes in the upland was slowest on the surface of the litter, but was dominated by termites at all soil depths. Similar to other studies, decomposition from microbial decay and termites was highest in aspen and lowest in pine. Our study indicates that changes in the frequency and amount of precipitation projected in future climate scenarios would likely have a greater impact on wood decomposition in poorly-drained wetland ecosystems than increased temperature.