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As coastal regions experience accelerating land loss, artificial substrates may be useful in restoration efforts to replenish sediment and facilitate plant colonization. Recycled glass sand is a potential artificial substrate for marsh building due to its sustainability, availability, and similarity to natural substrates. However, differences in texture and availability of microbiota necessitate investigating how it affects plant growth. We tested the effect of three substrates (conventionally used dredged river sand, recycled glass sand, and a mix) and inoculation with natural soil microbes on the biomass and root architecture of Black mangrove (Avicennia germinans) in a greenhouse experiment. We found neither substrate nor inoculum affected biomass; however, survival was lower in mixed substrate compared to dredged and glass sand, and live inoculum increased survival from 70 to 93%. Substrate affected root architecture: mangroves grown in glass sand had 55% lower fine root length, 51% lower specific root length (length/mass), and 26% larger average root diameter than mangroves grown in dredged sand. Although an unintended fungal infection byGeotrichum candidumkilled nearly 90% of infected propagules before the experiment, surviving plants had 81% higher biomass than uninfected plants. These findings suggest that while glass sand does not affect biomass, it may affect root architecture in ways that compromise soil stability. Furthermore, inoculation with live soil may boost restoration planting success across substrates, likely by reintroducing mutualists. Overall, recycled glass sand may be a viable restoration strategy with the caveat that the developing root architecture may differ from that in more natural substrates.
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This content will become publicly available on December 1, 2026
Sediment stability is optimized by manipulating planting design during coastal marsh establishment
Communities are increasingly harnessing the coastal protection functions of marshes and other coastal ecosystems within built infrastructure, developing nature-based designs to stabilize coastlines. These “living shorelines” often include planting ecosystem-engineering plants, which have traits that attenuate waves and facilitate sediment accretion while limiting erosion. However, failure is common during plant establishment, requiring interdisciplinary approaches to inform planting designs that enhance short-term sediment stability. Here we combine hydrodynamic modelling with mesocosm experiments to assess different planting approaches for the marsh grass Spartina alterniflora. The model, parameterized with traits measured in the experiments, showed that random arrangement of plants outperformed regular arrangements, reducing areas of high flow velocities and increasing tortuosity, facilitating sediment stability. Furthermore, wide-diameter Spartina clumps with increased biomass reduced flow better than small-diameter clumps, even when the area occupied by the vegetation site-wide is identical. Our experiments revealed multiple factors that influence the diameter and biomass of Spartina clumps, including plant source, sediment characteristics, and spatial arrangement of propagules. While some sources performed better than others, their relative performance varied with time and environment, suggesting that practitioners plant multiple sources to ensure incorporating high-performers in variable and often unexamined planting environments. Furthermore, clumping propagules during planting best generated the large, dense clumps that facilitate sediment stability.
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- Award ID(s):
- 1945685
- PAR ID:
- 10609211
- Publisher / Repository:
- Scientific Reports
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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