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Are elevation and open-water conversion of salt marshes connected?

January 29, 2020

Salt marsh assessments focus on vertical metrics such as accretion or lateral metrics such as open-water conversion, without exploration of how the dimensions are related. We exploited a novel geospatial dataset to explore how elevation is related to the unvegetated-vegetated marsh ratio (UVVR), a lateral metric, across individual marsh “units” within four estuarine-marsh systems. We find that elevation scales consistently with the UVVR across systems, with lower elevation units demonstrating more open-water conversion and higher UVVRs. A normalized elevation-UVVR relationship converges across systems near the system-mean elevation and a UVVR of 0.1, a critical threshold identified by prior studies. This indicates that open-water conversion becomes a dominant lateral instability process at a relatively conservative elevation threshold. We then integrate the UVVR and elevation to yield lifespan estimates, which demonstrate that higher elevation marshes are more resilient to internal deterioration, with an order-of-magnitude longer lifespan than predicted for lower elevation marshes.

Publication Year 2020
Title Are elevation and open-water conversion of salt marshes connected?
DOI 10.1029/2019GL086703
Authors Neil K. Ganju, Zafer Defne, Sergio Fagherazzi
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70209594
Record Source USGS Publications Warehouse
USGS Organization Woods Hole Coastal and Marine Science Center