LTREB: Long Term Studies of Salt Marsh Primary Production

This proposal builds upon decades of research on salt marsh primary production initiated in North Inlet, SC, since 1984. The research includes monthly nondestructive measurements of marsh cordgrass (Spartina alterniflora) populations and monthly assessments of soil chemistry and marsh surface elevation. This long-term research has uncovered fundamental insights into how salt marshes form, change over time, and support other life, and has reshaped our understanding of coastal wetland stability and regulation of marsh primary production. This research led to development of Marsh Equilibrium Theory, which explains how saltmarshes maintain stability and forecasts the survival of saltmarshes in the face of changing sea levels. This information is vital for understanding and planning for the consequences of rising sea level on coastal marine resources such as fisheries and coastal infrastructure. Continuing from existing core data and modeling efforts, this project aims to test three new hypotheses: 1) Marsh elevation gain is regulated by the production of belowground biomass and is proportional to the net production of the marsh ecosystem; 2) The rate of change of the elevation of the marsh surface is constrained by primary production rates and the decomposition of soil organic matter, and 3) Mineral deposition at the lower saltmarsh edge increases with accelerating sea-level rise while primary production declines. These investigations will include measuring decomposition rates of belowground biomass, analyzing DNA and RNA from decomposing plant tissue for microbial activities, and quantifying mineral deposition across marsh surfaces. Fieldwork will involve sediment core sampling and precise elevation measurements, correlating these with biomass and environmental factors. This project serves as a training ground for students and fosters interdisciplinary research. Educational outreach includes engaging civic and K-12 groups on marsh ecology and climate change through presentations and exhibits at the Hobcaw Barony Discovery Center, impacting over 16,000 annual visitors. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.