Variations in Vertical Accretion in a Louisiana Swamp


  • William H. Conner
  • John W. Day, Jr.


Subsidence, coastal forests, swamps, wetlands, flooding, bottomland hardwoods


Vertical accretion in a swamp forest was measured over marker horizons in two areas bordering Lake Verret, Louisiana beginning October 1984. In both areas, vertical accretion was related to the duration of flooding. South of the lake, vertical accretion was greatest at the edge of the lake (0.37 cm/month) and least 100 m inland (0.11 cm/month). Water levels and vertical accretion were also measured at three locations along a flooding/elevation gradient in a bottomland hardwood forest north of the lake. From June 1985 through August 1986, sedimentation was 0.01, 0.04, and 0.07 cm/month for dry, intermediate, and wet sites, respectively. The intermediate and wet plots were lost but the dry site was resampled in May 1987 and November 1988. Vertical accretion averaged 0.03 cm/month and 0.01 cm/month for 1986-87 and 1987-88, respectively. Unlike coastal marsh areas where storm-related events are important factors leading to sedimentation, timing and duration of flooding seemed to be most important in determining vertical accretion rates in this swamp forest system.