An official website of the United States government
Abstract AimsThe goal of this study was to explore the suitability of recycled glass sand for the growth of beach-adapted plant species given the potential environmental benefits of utilizing glass sand for beach and dune restoration in the face of dwindling natural sand resources. MethodsWe grew three species native to US Gulf of Mexico beaches (Ipomoea imperati(Vahl) Griseb.,I. pes-caprae(L.) R.Br., andUniola paniculata(L.)) in three greenhouse experiments in glass sand, beach sand, or mixtures. First, we investigated nutrient and microbial effects by growing each species in pure glass sand, beach sand, and 80%/20% mixtures of glass sand/beach sand. Second, we comparedU. paniculatagrowth in glass sand mixed with 100%, 75%, 50%, 25%, or 0% beach sand. These experiments included fertilizer and microbial sterilization treatments. Third, we investigated soil permeability effects by comparing growth of all species using different grain sizes of glass sand. ResultsOverall, plants produced significantly more biomass in beach sand than in glass sand, and the effect was more pronounced with the fertilizer treatment. There were significant effects of substrate mixtures and interactions with fertilizer treatments onUniolabiomass. Further, when glass sand grain sizes were manipulated, plant biomass was equal or higher in the coarsest glass sand compared to beach sand. ConclusionsOur results demonstrate that beach-adapted plants can grow in glass sand and suggest that recycled glass sand is a potential resource for ecological restoration with incorporation of soil amendments such as fertilizer and utilization of selected grain sizes.
more »
« less
This content will become publicly available on April 29, 2026
Field‐grown coastal dune plants exhibit similar survival, growth, and biomass in recycled glass substrate and natural beach sand
Restoration of coastal dunes following tropical storm events often requires renourishment of sand substrate dredged from offshore sources, although dredging has well‐described negative ecological impacts and high economic costs. As a potential solution, recycled glass sand (cullet) made from crushed glass bottles has been proposed as a potential replacement for dredging. However, glass sand substrates may have limited ability to provide support to coastal plant communities due to the absence of native soil microbial communities. To explore the potential use of glass sand as a substrate for dune plants in the Northern Gulf of Mexico, we compared the growth of Sea oats (Uniola paniculata), Beach morning‐glory (Ipomoea imperati), and Railroad vine (I. pes‐caprae) in glass sand to growth in live beach sand. To determine if inoculation of glass sand with native soil microbial communities improved survival, growth, and biomass production, we also tested plant growth in glass sand with native microbial amendments. Overall, we found no difference in the survival of the three dune species across three soil treatments and weak differences in plant growth and biomass production across our soil substrates. Our results suggest that glass sand substrates may be a viable option for coastal dune restoration, with limited differences between live beach sand, glass sand, and glass sand inoculated with native soil microbes. Restoration and replenishment of coastal dunes using glass sand as a substrate following tropical storms or sea‐level rise may allow coastal managers to reduce the economic and ecological damage associated with offshore sediment dredging.
more »
« less
- Award ID(s):
- 2230769
- PAR ID:
- 10633613
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Restoration Ecology
- ISSN:
- 1061-2971
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
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.more » « less
-
Coastal dunes are globally recognized as natural features that can be important adaptation approaches for climate change along urban and natural shores. We evaluated the recovery of coastal dunes on an intensively groomed urban beach in southern California over a six-year period after grooming was discontinued. Restoration actions were minimal and included installation of three sides of perimeter sand fencing, cessation of mechanical grooming and driving, and the addition of seeds of native dune plants. To track recovery, we conducted physical and biological surveys of the restoration site and an adjacent control site (groomed beach) using metrics including sand accretion, elevation, foredune and hummock formation, vegetation recovery, and wildlife use. Sediment accretion, elevation, and geomorphic complexity increased over time in the restoration site, largely in association with sand fencing and dune vegetation. A foredune ridge (maximum elevation increase of 0.9 m) and vegetated hummocks developed, along with a general increase in elevation across the restoration site (0.3 m). After six years, an estimated total volume of approximately 1,730 m3of sand had accreted in the restoration site and 540 m3of sand had accreted in the foredune ridge. Over the same period, more than a meter of sediment (vertical elevation change) accumulated along the perimeter sand fencing. Groomed control areas remained flat and uniform. The total cover of vegetation in the restoration site increased over time to a maximum of approximately 7% cover by the sixth year. No vegetation was observed on the groomed control site. Native plant species formed distinct zones across the restoration site beginning by the second year and increasing over time, with dune forming species aggregating closest to the ocean in association with the incipient foredune ridge. Ecological functions observed in the restoration area included presence of dune invertebrates, shorebird roosting, and use by a breeding federally threatened shorebird, the western snowy plover (Charadrius nivosus nivosus). Our findings on geomorphic and ecological responses of a pilot dune restoration on a heavily groomed urban beach provide new insights on the opportunities and expectations for restoring dunes as nature-based solutions for climate adaptation on urban shorelines.more » « less
-
Coastal dune restoration often focuses on weed removal to reestablish native vegetation communities. Point Reyes National Seashore (PRNS) initiated large‐scale dune restoration after becoming concerned about loss of dune and rare species habitat from spread of non‐nativeAmmophila arenaria(European beachgrass). Two projects removed beachgrass from 146 ha of heavily invaded dunes using either mechanical removal or herbicide treatment. PRNS conducted pre‐ and post‐restoration vegetation monitoring for 10 years post‐implementation, evaluating success in (1) eradicating beachgrass and (2) reestablishing vegetation communities similar to native dunes in cover, diversity, and species composition. Both methods eradicated beachgrass with annual retreatment. However, they were less successful in rebuilding vegetation communities with comparable native species cover and/or richness. Mechanical removal areas remained largely barren expanses of sand that struggled to support native plants except for a rare perennial, Tidestrom's lupine (Lupinus tidestromii). Tidestrom's lupine and other rare plants now number in the hundreds of thousands. Conversely, herbicide‐treated backdunes were dominated by standing dead beachgrass that resisted decomposition even after 7 years, which hampered native and rare plant establishment. Delayed decomposition was less of an issue in herbicide‐treated foredunes, because sand overwash buried necromass. Restored areas also contended with subsequent invasion by secondary plant invaders. By 2021, only older herbicide‐treated backdunes, and to a lesser extent, mechanical backdunes, showed signs of convergence with native dunes. Successful convergence may be hindered by lingering physical and microbial legacy effects of beachgrass invasion and treatment method. Adaptive restoration may be needed to counter effects and improve project success.more » « less
-
The U.S. Pacific Northwest (PWN) coastal dunes are mainly colonized by two non-native beachgrass species (i.e., Ammophila arenaria and A. breviligulata) and a native dune grass (Leymus mollis) that capture sand and build dunes of different morphology. Recently, a hybrid beachgrass was discovered with unknown consequences for dune evolution. We set up a common garden experiment including seven treatments and two control plots to understand the effect of native and non-native plant species on sand accretion and dune morphological evolution. After 1.6 years, sand volume increased the most in the non-native species plots with levels at least twice as high for A. arenaria as compared to the other plots. The hybrid species had moderate sand accretion but a survival rate of 1.4 and 2.1 times higher than its parent species and native species, respectively. These results provide new insights for U.S. PNW coastal dune management.more » « less
