Biophysical drivers of coastal treeline elevation

JGR Biogeosciences
By: , and 

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Abstract

Sea level rise is leading to the rapid migration of marshes into coastal forests and other terrestrial ecosystems. Although complex biophysical interactions likely govern these ecosystem transitions, projections of sea level driven land conversion commonly rely on a simplified “threshold elevation” that represents the elevation of the marsh-upland boundary based on tidal datums alone. To determine the influence of biophysical drivers on threshold elevations, and their implication for land conversion, we examined almost 100,000 high-resolution marsh-forest boundary elevation points, determined independently from tidal datums, alongside hydrologic, ecologic, and geomorphic data in the Chesapeake Bay, the largest estuary in the U.S. located along the mid-Atlantic coast. We find five-fold variations in threshold elevation across the entire estuary, driven not only by tidal range, but also salinity and slope. However, more than half of the variability is unexplained by these variables, which we attribute largely to uncaptured local factors including groundwater discharge, microtopography, and anthropogenic impacts. In the Chesapeake Bay, observed threshold elevations deviate from predicted elevations used to determine sea level driven land conversion by as much as the amount of projected regional sea level rise by 2050. These results suggest that local drivers strongly mediate coastal ecosystem transitions, and that predictions based on elevation and tidal datums alone may misrepresent future land conversion.

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Publication type Article
Publication Subtype Journal Article
Title Biophysical drivers of coastal treeline elevation
Series title JGR Biogeosciences
DOI 10.1029/2023JG007525
Volume 128
Issue 12
Year Published 2023
Language English
Publisher American Geophysical Union
Contributing office(s) Woods Hole Coastal and Marine Science Center, Eastern Ecological Science Center
Description e2023JG007525, 18 p.
Country United States
State Delaware, Maryland, Virginia
Other Geospatial Chesapeake Bay area
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