Category: Aridity: Dry sub-humid

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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.

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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.
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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.

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Riparian Buffer Zones

Similar names: Conservation buffers, Stream corridor bank enhancement, Riparian buffer strips and hedges, Terrestrial buffers, Riparian buffer systems

Riparian buffer zones are the interface between land and a river, stream or creek often characterised by riparian woodlands, forests and riparian strips. The plant habitats and natural communities along the river banks are better known as riparian vegetation and they are characterised by hydrophilic plants, bushy vegetation and forest systems. The presence of riparian buffer zones is crucial due to their role as natural biofilters and their protection of aquatic environments from excessive sedimentation, polluted surface runoff and erosion. Furthermore, they provide shelter, shade and food for many aquatic species.

Often the riparian zones are damaged by various anthropogenic activities such as agriculture, construction and silviculture. In this case, biological restoration can take place, with the most common practices being erosion control and revegetation. Furthermore, in some places riparian zones are fully lacking and reintroducing them could bring plenty of benefits to the local ecosystems. Because of the great biological function these systems have in supporting a diversity of species and landscapes, they are in some places subject to national protection mechanisms.

Initiating and restoring riparian buffers is crucial for the healthy functioning of riparian ecosystems. The vegetation around the banks of the river slows the flow of water which controls the power of the river and the destruction that could occur downstream. When near agricultural land, the riparian buffers filter various pollutants from agricultural runoffs, enhancing water quality via biofiltration. 

Disclaimer: Check whether Riparian Buffer Zones are subject to national protection in your area, as this could help with their protection and restoration.

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Muvuca Direct Seeding

Similar names: Seed-based land restoration, Direct sowing

Muvuca direct seeding is a nature restoration method, where a mix of seeds from dozens of native species at different successional stages are planted simultaneously into the ground. The method mimics natural regeneration mechanisms such as seed soil banks and seed rain. Better known conventional practice is direct seeding’s popular counterpart – transplanting, which is a technique of moving plants from one location to another, usually to preserve the optimal condition of the seedlings. Despite providing more control over the plant’s growth, transplanting doesn’t allow for a high variety of plant seeds to grow simultaneously.

The Muvuca system uses a high diversity of species and ensures longer-term operational efficiency, which in return enables mechanised restoration with reduced planting, low maintenance in terms of time and reduced costs. Planting can be done either manually or mechanised (using machinery such as tractors), which enables the scalability of the intervention. Furthermore, the grown plants through Muvuca become more robust and resistant to various weather conditions, which results in stronger root systems and overall healthier vegetation. Overall, Muvuca direct seeding can contribute to the scaling up of restoration efforts, while reducing costs and increasing the species diversity. Meanwhile, the demand for native species enables the promotion of conservation and well-being.

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Composting

Similar names: Organic Amendments

Composting is an effective method of organic waste management, involving the controlled aerobic decomposition of organic matter, such as plant and animal waste. This process results in Compost, a stable, humus-like material that can be directly applied to soil. The primary goal of Composting is to reduce the amount of organic waste sent to landfills while providing economic, environmental, and social benefits. When used in soil, Compost enriches it, reducing the need for chemical fertilizers and lowering potential methane emissions from landfills.

The Composting process (Source)

Due to its recycling nature, Composting is a cost-effective tool for managing organic waste, utilizing leftover materials from land-based processes. It offers a range of co-benefits that enhance land and soil regeneration practices. Agronomically, Composting supports crop yields, improves soil moisture content and workability, enhances crop nutritional quality, and suppresses weeds, pests, and diseases. Additionally, Composting provides broader environmental benefits by supplying essential nutrients (such as mineralized nitrogen, phosphorus, and potassium), reducing soil erosion, sequestering carbon, and improving soil biological properties and biodiversity.

Furthermore, Compost can be used as a mulching material in landscaping, garden management, and the restoration of abandoned quarries, among other applications.

Agricultural benefits of Composting (Source)

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Assisted Natural Regeneration

Similar names: Pruning, Kisiki Hai, Managed Regrowth

Assisted Natural Regeneration (ANR) is a simple, low-cost forest restoration method that can effectively convert deforested and degraded lands into productive forests and rangelands. The method uses a blend of active planting and passive restoration techniques, which help vegetation to naturally recover by eliminating barriers and threats to their growth. ANR is similar to Farmer-Managed Natural Regeneration (FMNR), with the difference that ANR applies to degraded forest lands and rangelands while FMNR is usually practised on croplands. Overall, ANR mimics the natural systems and habitats by supporting the land processes through ANR. 

ANR is a flexible restoration approach and could be adapted to various contexts and objectives. A set of ecosystem restoration techniques are being facilitated, to eliminate obstacles to plant growth and survival. Those could vary depending on a range of factors, such as location, land type, restoration goal, etc. Hence, local community engagement is crucial for successfully implementing and managing ANR. Their knowledge of the land and ancestral traditions offers the best indication of what techniques and practices would be most beneficial. The most common ANR techniques are visualized in the figure below.

(source)

In comparison to other regeneration techniques such as tree-planting campaigns, ANR has comparatively low implementation and maintenance costs. The method could be applied on a local and larger scale level, with some areas and contexts being more favorable than others when it comes to implementation (see Requirements). However, where implemented, ANR can create jobs and bring income to local communities, as the implementations would require establishment and maintenance.

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Stone Lines

Similar names: Cordons pierreux, stone bunds.

Stone lines are stones grouped in the shape of a line and placed along contours. The stones can be of different sizes. The goal of these lines is to conserve the soil and reduce runoff, as they are used to slow down water runoff and break its velocity. Hence, they increase infiltration and retain sediment and seeds to make water and nutrients available for crops. Stone lines are most suitable for water harvesting on slightly sloping plains (up to 5%) in semi-arid regions. For slopes starting from 5%, stone bunds can be used (see eyebrow terraces).

Stone lines are an easy and cheap intervention if stones are available in the immediate surroundings. This intervention is widely used in Africa, both in dry and humid areas. Moreover, stone lines are often used in combination with Zai Pits intervention for the rehabilitation of degraded and crusted lands. It is applied in semi-arid areas, on sandy and loamy soils where the slope is lower than 5%. A great example can be seen in Niger, where the combination of the two techniques is applied to capture runoff, making infiltration more efficient and improving nutrient availability. The pits have a diameter of 20-30 cm, and a depth of 20-25 cm and are spaced about 1 m apart in each direction. Stone lines are spaced 20-25 m apart on slopes of 2-5%. With this layout stone lines are quite small, usually, three stones wide and only one stone high and they are placed, along the contour lines, by hand. Very often grass grows between the stones leading to a greater infiltration and helping the accumulation of fertile sediments. Maintenance-wise, stone lines need to be repaired annually, in particular after heavy precipitation events.

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Terracing

Terracing is a method of farming and soil conservation on hills and sloped lands. It was traditionally used by the Incas and is widely practised around the world today. It involves the building of platforms, and forming step-like structures along a slope. The main goal of bench terraces is to periodically interrupt the slope of the terrain with flat sections; this helps to decrease the speed of water runoff,  significantly reducing soil erosion and surface runoff. By slowing down water speed, this intervention stops the washing away of topsoil containing important nutrients and promotes better water infiltration and soil moisture. The flat benches of the terraces create more effective and productive areas to farm on steep terrain.

There are two main types of terracing techniques: graded terracing and level terracing. With graded terracing, the slope can vary along the length of the terrace to direct water in the desired direction; this is especially useful for less permeable land. With level terracing, the terraces follow a contour line and do not vary in slope along this line, this ensures that water is more evenly distributed along the terrace. Stone or wooden walls are often used to hold terraces in place, although a simple earth wall without supporting material can be used with slopes and terraces on the smaller side. This intervention is similar to Fanya Juu and Fanya Chini which are specific types of terraces.

Terracing offers several ecological and socioeconomic benefits. Ecologically, it prevents soil erosion by slowing water flow, allowing it to infiltrate the soil and retain valuable topsoil, which is essential for agriculture. Terracing also manages water more effectively by evenly distributing it across levels, conserving water, reducing irrigation needs, and promoting nutrient cycling. It creates diverse habitats for various plant and animal species, enhancing biodiversity. Additionally, terracing stabilizes slopes, reducing the risk of landslides by minimizing soil pressure and movement, especially in regions with wet seasons. Socioeconomically, terracing increases land productivity on slopes, allowing for larger crop beds and easier use of machinery, thus boosting agricultural efficiency.

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Vegetative Lines

Vegetative lines involve the planting of lines of vetiver grass following the contour lines, along stream banks and roadsides, to create a hedge. These hedges act like semi-permeable barriers, aimed to hinder surface erosion as they slow down run-off and retain sediments picked up by excess rainwater. This setup improves water infiltration and helps to increase the ground moisture level. Their root systems also help stabilise the soil and prevent further soil erosion. Thus this provides increased stabilisation of embankments, gully erosion, roads and slopes. Furthermore, water runoff and soil runoff reductions are observed, at around 57% and 80% respectively.

Vetiver grass can grow on slopes of > 50% and can be planted on a high variety of soils (red latosols, black cracking vertisols, roadside rubble, C-horizon gravels, laterites, sodic, and saline soils). Furthermore, vetiver grass is resistant to different types of climatic conditions: rainfall from 600mm to 6000 mm /year and extreme temperatures of -14°C to 55°C, and could survive several months submerged in water. Vetiver grass can support high levels of toxicity by manganese, aluminium and other metals and high levels of soil acidity, salinity, alkalinity, and acid sulphate conditions. All in all, they provide great solutions as they are non-invasive, fire resistant, and regrow quickly and be used as mulch, fuel (vetiver energy value is 55% the energy value of coal), and as fodder. Finally, vetiver grass is very efficient in stabilising Semi-Circular Bunds, Eyebrow Terraces or Negarim.

Very similar to the intervention described above is the so-called “Vegetative lines with cactus”. This intervention is based on the same principle as the Vegetative lines with vetiver grass, but it is suitable for drier environmental conditions (0 – 600mm). Like some other interventions, over time, this type of intervention can lead to the formation of terraces due to tillage and water erosion between the hedges.