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The University of Massachusetts Amherst

Spartina alterniflora Biomass Allocation and Temperature: Implications for Salt Marsh Persistence with Sea-Level Rise

Authors:

Sarah Crosby

Angus Angermeyer

Jennifer Adler

Mark Bertness

Linda Deegan

Nathaniel Sibinga

Heather Leslie

+2 more
Publication Type:
Journal Article
Year of Publication:
2017
Secondary Title:
Estuaries and Coasts
ISSN:
1559-2723
DOI:
10.1007/s12237-016-0142-9
Pages:
213-223
Volume:
40
Year:
2017
Date:
Jan-01-2017

Abstract

To predict the impacts of climate change, a better understanding is needed of the foundation species that build and maintain biogenic ecosystems. Spartina alterniflora Loisel (smooth cordgrass) is the dominant salt marsh-building plant along the US Atlantic coast. It maintains salt marsh elevation relative to sea level by the accumulation of aboveground biomass, which promotes sediment deposition and belowground biomass, which accretes as peat. Peat accumulation is particularly important in elevation maintenance at high latitudes where sediment supply tends to be limited. Latitudinal variation in S. alterniflora growth was quantified in eight salt marshes from Massachusetts to South Carolina. The hypothesis that allocation to aboveground and belowground biomass is phenotypically plastic was tested with transplant experiments among a subset of salt marshes along this gradient. Reciprocal transplants revealed that northern S. alterniflora decreased allocation to belowground biomass when grown in the south. Some northern plants also died when moved south, suggesting that northern S. alterniflora may be stressed by future warming. Southern plants that were moved north showed phenotypic plasticity in biomass allocation, but no mortality. Belowground biomass also decomposed more quickly in southern marshes. Our results suggest that warming will lead northern S. alterniflora to decrease belowground allocation and that belowground biomass will decompose more quickly, thus decreasing peat accumulation. Gradual temperature increases may allow for adaptation and acclimation, but our results suggest that warming will lower the ability of salt marshes to withstand sea-level rise.