Salt Marsh Vegetation Change at Cape Cod National Seashore: A Synopsis of 20 Years of Monitoring Between 2003 and 2023
Smith SM. 2026. Salt Marsh Vegetation Change at Cape Cod National Seashore: A Synopsis of 20 Years of Monitoring Between 2003 and 2023. Science Report. NPS/SR—2026/521. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2317883
The vegetation of salt marshes within Cape Cod National Seashore (CACO) is regularly assessed as part of the park’s long-term ecological monitoring program. The main objective of this report is to describe the extent of structural and taxonomic shifts in salt marsh plant communities that have occurred over the last ~20 years. Analysis of data between 2003 and 2023 suggests that ground-level monitoring of salt marsh vegetation is tracking changes reasonably well. CACO's salt marshes have exhibited major floristic changes in recent decades with the dominant low and high marsh taxa (Spartina alterniflora and S. patens, respectively) generally decreasing, although there is large spatial variation among and within marsh sites. The abundance of transitional species (marsh border and terrestrial species) has also declined, leading to a reduction in species richness. These species’ shifts and the loss of the foundational salt marsh grasses are due mainly to sea level rise (SLR), crab herbivory, and marsh edge retreat (lateral erosion). Unfortunately, the development of new marsh from upslope migration into the terrestrial environments is not occurring at a pace that substantially offsets the losses within the original marsh footprints.
- Type
- Published Report
- Authors
- Smith, Stephen
- Date of Issue
- 2026-10
- Publisher
- National Park Service
- DOI
- 10.36967/2317883
- Units
- CACO , NRSS