ABSTRACT

Feher, L.C.; Willis, J.M., and Hester, M.W., 2018. Importance of site history and environmental setting on soil properties in restored Louisiana back-barrier island salt marshes.

Although previous studies have identified significant differences between the soils of salt marshes restored with dredged material and natural marshes, it is unclear how these differences might affect plant community composition, soil development, and the overall stability of the marsh through time. Using soil shear strength as a metric of soil integrity and resistance to erosion, this study utilized field surveys of one natural and two restored back-barrier island salt marshes in coastal Louisiana to examine differences in shear strength and other soil properties in relation to site history and environmental setting. Soil properties at both restored sites were largely dependent on the source of the fill material in addition to site-specific restoration approaches. Soils at the younger restored marsh were significantly more finely grained than soils at either the older restored marsh or the natural marsh. High soil conductivity resulting from limited tidal exchange likely hindered plant establishment at the younger restored marsh, whereas the soil properties and vegetation cover of the older restored marsh were relatively similar to that of the natural marsh. Soil shear strength was comparable between the natural and restored marshes but was significantly higher in areas with finely grained soils. Therefore, differences in soil properties between the natural and restored marshes may reflect site-specific restoration approaches. As such, sediment source and hydrologic regime are important drivers of back-barrier marsh restoration success that can exert strong influences on soil development and likely the resilience and sustainability of these habitats.

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