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Introduction

Introduction.

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Introduction

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  1. Introduction • Soft engineering projects are needed to restore, rehabilitate, or recreate degraded salt marshes, with cordgrasses (genus Spartina) being one of the most popular biotools. Thus, Spartina alterniflora Liosel, S. foliosa Trin., and S. anglica Hubb. have been used in salt marsh manipulation and restoration projects in North America (Konisky et al. 2006), Asia (An et al. 2007), and Europe (Bakker et al. 2002). • However, little is known about restoration of European salt marshes using Small cordgrass (Spartina maritima (Curtis) Fernald), the only native cordgrass in many European estuaries. Improving our knowledge is a key step for the restoration of these estuaries given that using exotic cordgrasses for salt marsh restoration may have significant negative environmental impacts (Huang & Zhang 2007).

  2. Restoring With Spartina maritima • Our salt marsh restoration project was carried out from November 2006 to January 2007 in Odiel Marshes (S.W. Iberian Peninsula; lat 37089–37209N, long 6459–7029W). The restored area, known locally as ‘‘Punta del Sebo,’’borders the main channel of the estuary. Before the installation of an industrial site in the 1960s, these marshes were used by Huelva citizens as a recreational area, originally occupied by multiple Spartina maritima tussocks.

  3. Restoring With Spartina maritima • Previous to restoration of the marshes, the sediments were polluted with heavy metals (VanGeen et al. 1997), and several oil deposits were found 1.5 m below the sediment surface due to historic oil spills from neighboring industries. Furthermore, the South American neophyte Spartina densiflora Brongn., which colonizes a wide range of habitats and competitively displaces native species (Nieva et al. 2001).

  4. Restoring With Spartina maritima • The presence of native vegetation in the low marshes was restricted to one stand of S. maritima of 6,026 m2 and isolated clumps of Sarcocornia perennis (Mill.) Scott ssp. perennis, Sarcocornia perennis X fruticosa (Figueroa et al. 2003), Atriplex portulacoides L.,and the annual Salicornia ramosissima J. Woods. A degraded landscape dominated by unvegetated mudflats was the most obvious consequence of these conservation problems.

  5. Restoring With Spartina maritima Our ecological restoration project had four specific goals: • (1) to recover native vegetation, restoring the degraded landscape • (2) to phytostabilize oil-polluted sediments • (3) to prevent erosion and stabilize banks • (4) to promote the conservation of S. maritima, an endangered species included on some European red lists

  6. Restoring With Spartina maritima • Plantation zones: • were delimited with small wood stakes between 1.50 and 2.30 m Spanish hydrographic zero(SHZ) (8.37 ha) based on the lower general distribution limit of S. maritima in the tidal range (1.41 m SHZ) (Castillo et al. 2000). • Spartina maritima clumps had to be obtained from natural populations because it does not produce seeds and it is not produced at nurseries.

  7. Restoring With Spartina maritima • To minimize extraction impacts and to increase biodiversity at the restored marshes, the extraction of S. maritima plants was spatially dispersed and only done where it was being outcompeted by Sarcocornia perennis. Then, fragments of Sarcocornia perennis were transplanted together with S. maritima. • Natural tussocks of S. maritima were fragmented in situ to small clumps (about 20 tillers) and transported to the intervention area by boats. A mean of 80 clumps were obtained from every 1 m2 of the natural population. • Additionally, A. portulacoides clumps cultivated at a nursery were planted at the edges of interior marshes to accelerate its colonization. The invasive cordgrass S. densiflora was eliminated manually from 2.00 ha around the site. Spartina maritima Sarcocornia perennis

  8. One year after transplantation Survivorship of transplanted S. maritima clumps has been very high (99% at channel banks and 75% at interior marshes) and they have colonized surrounding bare sediments at expansion rates of 1.1 ± 0.0 cm/month (n = 76). At the same time, Sarcocornia perennis has been growing at interior marshes accompanying 20% of the cordgrass clumps with an expansion rate of 1.8 ± 0.2 cm/month (n = 21). Atriplex portulacoides clumpsshowed a survivorship of 90% and newly germinated emergent seedlings of S. densiflora appeared at three interior marshes and require manual weeding for removal. Establishment of new species is expected during the development of ecological succession at interior marshes because adequate propagule sources are present in the neighboring marshes and dispersal is not limited.

  9. Currently Project environmental monitoring: • Birds, invertebrates, vegetation, fish ...

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