Marsh Restoration Using Thin Layer Sediment Application.

Recent interest has focused on restoration techniques that introduce thin layers of sediment onto degrading marsh surfaces. A restoration project resulted in the placement of 5-19 cm of sediment onto vegetated marsh areas and 32-82 cm of sediment into degraded open water panne features. Results indicate that significant differences in soil physical properties existed between the placed sediments and the buried native marsh soils. For example, six months after project implementation panne bulk density increased from 0.22 ± 0.02 g/cm³ to .83 ± 0.09 g/cm³, surpassing the threshold required to support Spartina Alternaflora establishment. Soil nutrient and microbial properties also differed between placed sediments and buried marsh soils. Notably, buried marsh soils remained active, with potentially mineralizable nitrogen results demonstrating the capacity for buried soils to provide labile nutrient sources during vegetation recruitment. Results suggest that thin layer sediment placement techniques may increase restoration timeframes by maintaining native vegetation seed sources, rhizomes, and microbial communities in near-surface soils compared to other restoration approaches. Examining short term changes in soil microbial activity provides rapid-response indicators of restoration outcomes; additional research will monitor changes in soil properties over time.