Date of Completion

7-23-2019

Embargo Period

7-22-2021

Advisors

Ashley Helton, Beth Lawrence, Chris Elphick

Field of Study

Natural Resources

Degree

Master of Science

Open Access

Open Access

Abstract

Salt marsh vegetation zones are good indicators of soil conditions and will shift in response to large-scale changes to their environment such as sea-level rise and restoration activities. The goal of our study was to characterize the relationship between soil denitrification potential and salt marsh vegetation zones in tidally restored and unrestricted coastal marshes, and to use vegetation zones to predict how sea-level rise may influence landscape-scale denitrification. We conducted denitrification enzyme activity assays (DEA) on sediment collected from 20 salt marshes across Connecticut and found denitrification potential to be 7 and 17 times lower in short-form Spartina alterniflora zones compared to zones dominated by Spartina patens and Phragmites australis respectively. Denitrification potential was not significantly different between tidally restored and unrestricted coastal marshes, thus landscape-scale changes in denitrification after tidal restoration are likely to be associated with shifts in vegetation rather than differences driven by restoration status. Based on sea-level rise model projections, the replacement of S. patens by short-form S. alterniflora is expected to be widespread across Connecticut, decreasing statewide potential denitrification from the low-to-high marsh transitional zone by at least 500 kg-N/ hr by 2085. Our results suggest that vegetation zones can serve as predictors of landscape-scale denitrification rates and their response to rapid changes occurring in salt marshes.

Major Advisor

Ashley Helton

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