This paper estimates the implicit value of salt marsh ecosystem services along the French
Atlantic coast using a hedonic pricing framework applied to over one million residential
transactions across 16 departments (2012–2021). We estimate separate Box-Cox hedonic
models for each department, systematically rejecting the log-linear specification and
documenting substantial cross-departmental heterogeneity in marsh capitalization effects. Salt
marsh proximity exerts a predominantly negative effect on property prices in most
departments, with sign reversals in coastal configurations where marshes form part of a
broader amenity bundle. The PPRi flood risk indicator is positively capitalized in most
departments, consistent with a regulatory salience effect rather than risk compensation. These
results suggest that housing markets capitalize regulatory constraints and amenity bundles
rather than ecosystem service value per se, with direct implications for coastal conservation
policy and benefit-transfer exercises
