Date of Award

8-2018

Rights

© 2018 Tessa M. Dowling

Document Type

Thesis

Degree Name

Master of Science in Biological Sciences

Department

Biological Science

First Advisor

Gregory Zogg

Second Advisor

Steven Travis

Third Advisor

Pamela Morgan

Abstract

Although high elevation salt marsh plants, such as Spartina patens (salt hay) can cope with accelerated sea level rise by migrating inland, it is not well known whether environmental factors, such as soil, plant litter, and salinity, will influence the ability of S. patens to colonize upland forest areas. For one growing season, I tested how S. patens vegetative growth (the final number of stems, aboveground stem biomass, and belowground rhizome biomass) and reproduction (presence of flowers) responded to upland or marsh soil, the presence or absence of plant litter, and 4.5ppt or 14.5ppt salinity levels. In order to determine if the source location of the plant influenced their response to treatment effects, I collected S. patens plants from three Maine salt marshes in the townships of Scarborough, Biddeford, and Wells. Litter and salinity treatments did not significantly affect vegetative growth, and they only affected flowering in a three-way interaction with site. All vegetative and reproductive measures were significantly affected by soil and the site x soil interaction - S. patens collected from Biddeford and Wells grew significantly less in the upland soil compared to the marsh soil, but Scarborough plants grew equally well in both soil treatments. One possible explanation for why plants from the three sites responded differently to soil treatments was that the Scarborough site had a significantly lower percent soil organic matter content, and therefore, was more similar to upland in soil organic matter content than the other two sites. These results suggest that S. patens populations from a site with low soil organic content will be more successful adjusting to upland soil than plants from high soil organic matter sites, which would give those populations accustomed to low organic matter an advantage when migrating inland. The ability to identify S. patens sites that will successfully migrate inland, by measuring soil organic content or other site characteristics, is vital if conservation efforts are going to protect the S. patens populations most likely to persist in the face of sea level rise.

Comments

Master's thesis

This work was supported by grants from the Society of Wetlands Scientists (SWS) and the Maine Association of Wetland Scientists (MAWS).

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