Dune Planting

Synonyms: Dune fixation, wickerworks

Dune grass planting is a dune restoration technique that reinforces dune stability by establishing vegetation capable of trapping, anchoring, and accumulating sand. This process is effective in both coastal and inland dunes, where wind erosion, overgrazing and sand mobility pose threats to ecosystem stability.

In coastal settings, grasses like marram grass (Ammophila arenaria) and lyme grass (Leymus arenarius) are essential for initiating and maintaining dune growth. Marram grass, in particular, grows vigorously in sandy environments, extending its roots both horizontally and vertically as sand accumulates. This growth pattern allows the grasses to trap sand and stabilize dune surfaces, reducing wind speeds at the ground level and encouraging sand to settle. By reducing the velocity of surface winds, the grasses create a self-reinforcing cycle of sand accumulation and root expansion. This process promotes the formation of “yellow dunes” further inland, while more resilient species like sand couchgrass (Elymus farctus) stabilize the vulnerable “foredune” zone nearest to the shoreline, where occasional seawater inundation occurs.

In arid, inland dune regions where desertification is a concern, planting drought-resistant vegetation such as Leptadenia pyrotechnica and Calligonum comosum serves a similar function. These species prevent sand from moving with the wind by creating dense root systems that hold soil in place. The combined horizontal and vertical growth of these plants enhances soil retention, improves the dune’s physical stability, and reduces the likelihood of sand encroachment on nearby agricultural or pastoral lands. By acting as windbreaks and anchoring loose sand, these plants encourage dune formation and mitigate the physical impacts of wind erosion.

Dune Thatching

Covering exposed dune faces – or blowouts – with waste cuttings from forestry or other low-cost materials is a technique called dune thatching. It is used to stabilize sand, reduce trampling, and protect vegetation. When locally sourced, thatching materials are inexpensive, and the process requires no machinery or skilled labor. This method is typically combined with dune grass planting to further enhance dune stability. 

Properly applied thatch can aid dune recovery and provide resistance to erosion, although it cannot fully protect areas where waves frequently cause damage. The thatch slows surface wind speeds, encouraging sand to settle and accumulate. The effectiveness of this approach depends on the presence of blown sand, frequency of wave impact, presence of vegetation, and level of maintenance. Planting dune grasses after thatching can further improve dune recovery and stability over time. 

In this intervention we distinguish two types dune thatching:

  • Dune thatching with old (Christmas) trees:  Creating a natural barrier by digging in old (christmas trees) in a line parallel to the shoreline. This barrier promotes the entrapment of sand and in combination with dune grass planting this can stabilize dunes and promote formation of new dunes.

  • Dune thatching with millet stalk palisades: Creating physical sand barriers from dried plant palisades can be arranged in various ways depending on the level of sand dune destabilization. In heavily encroached areas, millet stalk palisades arranged in square grids can act as considerable wind catchment zones and prerequisite for revegetation. After two years, these palisades tend to fall apart and decompose and restored vegetation takes over the dune fixation function.

Dune Fencing

Building semi-permeable fences along the seaward or the prevailing wind side of dunes encourages windblown sand to accumulate, reduces trampling, and protects both existing and newly planted vegetation. Various fencing materials can effectively enhance natural dune recovery. This type of fencing is often combined with other management practices to promote dune stabilization and minimize environmental impact.

The use of dune fencing for wind erosion control and dune stabilization has a long history. Its success relies on factors such as the fence’s void-to-solid ratio, the availability of wind-driven sand, the frequency of wave activity at the fence line, and the amount of vegetation present to help stabilize accumulated sand. Combining dune fencing with other strategies, such as Dune Planting or Dune Thatching, can help establish new foredunes and further enhance stability.

Seagrass Seedbags

A seed-based intervention using mesh “seed bags” is a promising long-term approach to restore degraded seagrass meadows, particularly in more sheltered coastal areas. In this method, small mesh bags filled with seagrass seeds or fertile root cuttings are dispersed across the seafloor. These bags protect seeds from currents, allowing them to settle and germinate securely. Using adult plants, such as bare-rooted shoots, often enhances success rates and speeds up establishment, making this approach both effective and relatively low maintenance. Additionally, the flexibility of seed bag placement enables restoration efforts in deeper waters when sufficient anchoring materials, like rope or string, are available. This large-scale restoration technique offers an efficient and scalable way to rehabilitate seagrass meadows, fostering critical marine habitats and improving ecosystem health.

Sediment Tubes

Encouraging natural colonization of boat-damaged seagrass beds, this technique involves filling fabric tubes with sediment and seagrass seeds to speed up recovery, and placing them along damaged scars from anchors and propellers to ensure reconnection of the seagrass meadow.  

By returning these damaged segments to the appropriate elevation, the intervention prevents further erosion and scouring by water currents as well as protects peripheral rhizomes from excessive sunlight exposure.

Hessian Mattresses

Hessian mattresses are an innovative and eco-friendly solution for seagrass restoration projects. Made from biodegradable jute material, these mats provide a sediment-free, low-cost method for transplanting seagrass seedlings to degraded coastal areas, including sites impacted by mooring scars. By anchoring seagrass seedlings within the hessian fabric, the mattresses help stabilize the plants, protect them from being swept away by currents, and encourage healthy root establishment. Over time, the hessian material naturally decomposes, leaving behind a flourishing seagrass bed that restores marine biodiversity, improves water quality, and provides essential habitats for marine life.