Avicennia germinans and Spartina alterniflora soil shear strength and belowground biomass data near Port Fourchon, LA
Data files
Jan 12, 2026 version files 94.63 KB
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Manuscript_ScientificReports_data_1.12.26.xlsx
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README.md
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Abstract
Subtropical black mangrove (Avicennia germinans) is expanding into higher latitudes and encroaching on existing temperate salt marshes with the potential to alter a variety of ecological processes. In the Mississippi River Delta (Louisiana, USA), wave-driven marsh edge erosion is on the order of meters per year and accounts for half of the total sizable marsh loss. Here, we show that edge erosion is reduced by 40-60% when colonized by Avicennia as compared to salt marsh dominated by Spartina alterniflora. The lower erosion rate in sites dominated by Avicennia is associated with a greater soil shear strength, more live belowground biomass, and deeper roots. Furthermore, Avicennia reduces edge erosion only when there are dense, well-established stands. Marshes with sparse Avicennia cover had similar edge erosion rates to those with Spartina, likely due to lower and more shallow root biomass. Avicennia at 10 m inland also had similar soil shear strength and live belowground biomass as those at the marsh edge, suggesting that as the marsh erodes, newly exposed Avicennia will be better able to withstand wave action as compared to Spartina. Overall, climate-driven Avicennia expansion will not prevent marsh edge erosion, but it will significantly slow it down. Avicennia germinans could be used for restoration and a nature-based solution to reduce edge erosion, with efforts that allow Avicennia ~5 years to mature before being exposed along the marsh edge.
Dataset DOI: 10.5061/dryad.02v6wwqh9
Description of the data and file structure
This dataset contains soil shear strength (kPa) and belowground biomass (g) data collected near Port Fourchon, LA (USA). Study sites were selected using aerial imagery and ground reconnaissance based on the abundance of Avicennia, Spartina, and their location relative to wave action. Sites were classified as either Dense Avicennia, i.e., 100% Avicennia cover, Sparse Avicennia, i.e., 50% Avicennia cover and 50% Spartina cover, or Dense Spartina, i.e,. 75 – 100% Spartina cover.
Field measurements of soil shear strength, live and dead belowground biomass, bulk density, and % organic matter were taken at two Dense Avicennia sites, two Sparse Avicennia sites, and two Dense Spartina sites. At each study site, three transects were established approximately 5-10 m apart. Along each transect, elevation was measured at 2 m intervals from the marsh edge to 25 m inland using a Leica GS14 GNSS Receiver (Leica v. 7.03). Soil shear strength was measured at distances of 2, 10, and 20 m along one of the three transects at each site using a Humboldt Shear Vane. Eight replicate measurements were taken at each distance at depths of 5, 15, 25, 35, 45, 55, and 65 cm. Belowground biomass was collected at 2 and 20 m distances, using a sharpened PVC soil core (15.2 cm diameter x 45 cm depth). Bulk density and % organic matter were sampled using a russian peat core to a depth of 65 cm (5 cm diameter). Soil cores were cut into 5 cm depth sections and brought back to the laboratory, where they were stored cold before analysis.
Belowground biomass cores were cut into 5 cm depth sections and rinsed through a 1 mm sieve. Roots and rhizomes were then separated by species, live/dead, and dried at 60°C to a constant weight. Soil bulk density was determined for each of the 5 cm depth sections following drying at 60°C to a constant weight and calculation of dry mass over volume. Soil samples were then ashed in a muffle furnace at 550°C for five hours, and the % organic matter was calculated as the percent dry mass loss.
Files and variables
File: Manuscript_ScientificReports_data_1.12.26.xlsx
Description: Soil shear strength, belowground biomass, bulk density, and % organic matter from sites with dense Avicennia germinans, Sparse Avicennia germinans, and Dense Spartina alterniflora sites near Port Fourchon, LA (USA)
Variables (Headers)
- Article_Name: Site name used in the manuscript 'Avicennia germinans and Spartina alterniflora soil shear strength and belowground biomass data near Port Fourchon, LA
- Site: Site name (number) used during data collection and analysis
- Site.txt: Site name (letter) used during data collection and analysis
- Species: Species name (S. alterniflora = Spartina alterniflora, and A. germinans = Avicennia germinans)
- Distance (m): Distance from the edge of the marsh
- Depth (cm): Depth from the marsh surface
- Shear_Strength: Soil Shear Strength (kPa)
- Sample: Sample number (number) used during data analysis
- Sample_txt: Sample number (letter) used during data analysis
- Live_BB: Live Belowground Biomass (g)
- Dead_BB: Dead Belowground Biomass (g)
- Total_BB: Total Belowground Biomass (g)
- Bulk Density (g/cm3)
- Organic Matter (%)
- Layer: Upper (0-20cm) and Lower (20-65 cm)
- Location: Site located near Fourchon or Grand Isle