3 research outputs found
Effects of mangrove cover on coastal erosion during a hurricane in Texas, USA
We tested the hypothesis that mangroves provide better coastal protection than salt marsh vegetation using 10 1,008-m2 plots in which we manipulated mangrove cover from 0 to 100%. Hurricane Harvey passed over the plots in 2017. Data from erosion stakes indicated up to 26 cm of vertical and 970 cm of horizontal erosion over 70 months in the plot with 0% mangrove cover, but relatively little erosion in other plots. The hurricane did not increase erosion, and erosion decreased after the hurricane passed. Data from drone images indicated 196 m2 of erosion in the 0% mangrove plot, relatively little erosion in other plots, and little ongoing erosion after the hurricane. Transects through the plots indicated that the levee (near the front of the plot) and the bank (the front edge of the plot) retreated up to 9 m as a continuous function of decreasing mangrove cover. Soil strength was greater in areas vegetated with mangroves than in areas vegetated by marsh plants, or nonvegetated areas, and increased as a function of plot-level mangrove cover. Mangroves prevented erosion better than marsh plants did, but this service was nonlinear, with low mangrove cover providing most of the benefits
Effects of mangrove cover on coastal erosion during a hurricane in Texas, USA
We tested the hypothesis that mangroves provide better coastal protection than salt marsh
vegetation using ten 1,008 m2 plots in which we manipulated mangrove cover from 0 to 100 percent.
Hurricane Harvey passed over the plots in 2017. Data from erosion stakes indicated up to 26 cm of
vertical and 970 cm of horizontal erosion over 70 months in the plot with 0 percent mangrove cover,
but relatively little erosion in other plots. The hurricane did not increase erosion, and erosion
decreased after the hurricane passed. Data from drone images indicated 196 m2 of erosion in the 0 %
mangrove plot, relatively little erosion in other plots, and little ongoing erosion after the hurricane.
Transects through the plots indicated that the levee (near the front of the plot) and the bank (the front
edge of the plot) retreated up to 9 m as a continuous function of decreasing mangrove cover. Soil
strength was greater in areas vegetated with mangroves than in areas vegetated by marsh plants, or
nonvegetated areas, and increased as a function of plot-level mangrove cover. Mangroves prevented
erosion better than marsh plants did, but this service was non-linear, with low mangrove cover
providing most of the benefits.Accepted manuscrip
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Seagrass Abundance Predicts Surficial Soil Organic Carbon Stocks Across the Range of Thalassia testudinum in the Western North Atlantic
The organic carbon (Corg) stored in seagrass meadows is globally significant and could be relevant in strategies to mitigate increasing CO2 concentration in the atmosphere. Most of that stored Corg is in the soils that underlie the seagrasses. We explored how seagrass and soil characteristics vary among seagrass meadows across the geographic range of turtlegrass (Thalassia testudinum) with a goal of illuminating the processes controlling soil organic carbon (Corg) storage spanning 23° of latitude. Seagrass abundance (percent cover, biomass, and canopy height) varied by over an order of magnitude across sites, and we found high variability in soil characteristics, with Corg ranging from 0.08 to 12.59% dry weight. Seagrass abundance was a good predictor of the Corg stocks in surficial soils, and the relative importance of seagrass-derived soil Corg increased as abundance increased. These relationships suggest that first-order estimates of surficial soil Corg stocks can be made by measuring seagrass abundance and applying a linear transfer function. The relative availability of the nutrients N and P to support plant growth was also correlated with soil Corg stocks. Stocks were lower at N-limited sites than at P-limited ones, but the importance of seagrass-derived organic matter to soil Corg stocks was not a function of nutrient limitation status. This finding seemed at odds with our observation that labile standard substrates decomposed more slowly at N-limited than at P-limited sites, since even though decomposition rates were 55% lower at N-limited sites, less Corg was accumulating in the soils. The dependence of Corg stocks and decomposition rates on nutrient availability suggests that eutrophication is likely to exert a strong influence on carbon storage in seagrass meadows