Spartina alterniflora salt marshes are among the most productive ecosystems on earth, and represent a substantial global carbon sink. Understanding the spatial heterogeneity in the distribution of both above- and below-ground carbon in these wetland ecosystems is especially important considering their potential in carbon sequestration projects, as well as for conservation efforts in the context of a changing climate and rising sea-level. Through the use of extensive field sampling and remote sensing data (Light Detection and Ranging - LiDAR, and aerial images), we sought to map and explain how vegetation biomass and soil carbon are related to elevation and relative sea-level change in a S.alterniflora dominated salt marsh on Galveston Island, Texas. The specific objectives of this study were to: 1) understand the relationship between elevation and the distribution of salt marsh vegetation percent cover, plant height, plant density, above-and below-ground biomass, and carbon, and 2) evaluate the temporal changes in relative sea-level history, vegetation transitions, and resulting changes in the patterns of soil carbon distribution. Our results indicated a clear zonation of terrain and vegetation characteristics (i.e., height, cover and biomass). In the soil profile, carbon concentrations and bulk densities showed significant and abrupt change at a depth of ~10-15cm. This apparent transition in the soil characteristics coincided temporally with a transformation of the land cover, as driven by a rapid increase in relative sea-level around this time at the sample locations. The amounts of soil carbon stored in recently established S.alterniflora intertidal marshes were significantly lower than those that have remained in situ for a longer period of time. Thus, in order to quantify and predict carbon in coastal wetlands, and also to understand the heterogeneity in the spatial distribution of carbon stocks, it is essential to understand not only the elevation, the relative sea-level rise rate, and the vertical accretion rate - but also the history of land cover change and vegetation transition.
|Number of pages||10|
|Journal||Estuarine, Coastal and Shelf Science|
|State||Published - Mar 5 2015|
Bibliographical noteFunding Information:
The first author acknowledges two fellowships; Schlumberger Faculty for Future Fellowship from Schlumberger Foundation and Tom Slick Senior Graduate Fellowship from the College of Agriculture and Life Sciences, Texas A&M University. The authors also thank Ricardo Colon-Rivera and Trevor Pattillo for their hard work during field data collection, Andy Crane and Timothy Rogers for their assistance in processing and analyzing field samples, and the Department of Ecosystem Science and Management, at TAMU for various other supports during the study period. We would also like to acknowledge the NASA New Investigator grant (NNX08AR12G) for partial support for data analysis.
- Salt marsh
- Sea-level history
- Spartina alterniflora
ASJC Scopus subject areas
- Aquatic Science