Revegetation

Revegetation, also known as vegetation rehabilitation or restoration, involves planting locally adapted grass and shrub species to establish a stable, self-sustaining ecosystem resembling the original environment. This can also increase surface roughness and thus reduce ground-level wind speed. The value of re-establishing vegetation on erosion-prone lands largely depends on the orientation, spacing, height, and rooting depth of the selected plants. While other considerations may favour different orientations, vegetation is most effective at reducing dust emissions when planted in rows perpendicular to the prevailing wind direction. Although plant spacing is influenced by species characteristics and water availability, denser plantings generally provide stronger dust suppression. Taller, more rigid species create greater aerodynamic drag, and the deep root systems of some species offer improved anchorage and access to subsurface moisture. Revegetation through perennial crops, grass strips, and shrubs can support a variety of cropping and grazing systems, ideally as part of wider landscape restoration programmes.

Halophytes, which are salt-tolerant plants and forbs, can be used to revegetate playas, coastal zones, and other saline environments. Some Atriplex species (saltbushes) are recognised for their potential as livestock feed and fodder, while psammophytes can stabilise sand dunes with their root systems. In hyper-arid deserts, large-scale planting of desert-adapted species can slow the advance of mobile sands when rainfall is sufficient. In arid and semi-arid regions, a combination of straw checkerboards and the planting of drought-tolerant shrubs and cacti can create a more stable surface and a sheltered microclimate that supports a healthy and more resilient land cover.

The cost of revegetation largely depends on the extent of soil and land degradation, as well as on sowing, watering, and fertilisation requirements, the availability of seeds, and the survival rate of plants (adaptive capacity). Cost-efficient methods include mechanical and aerial seeding, incorporating species that fix nitrogen to reduce fertiliser requirements, conducting prescribed burns that contribute to revegetation in fire-dependent ecosystems, and using microcatchment rainwater harvesting to improve survival rates during the critical growth phases.

Case Studies

Planting saltbush at Owens Lake showed that a vegetation cover of just 20% reduced emissions by almost 100%. Since vegetation cover typically decreases by around 10% in winter, a minimum coverage of 30% in autumn was established to ensure effective dust control throughout the year. This approach cost around USD 36 million per square mile to implement, with ongoing annual maintenance costing an additional USD 2-3 million per square mile, largely due to damage caused by burrowing animals.

In the Aral Sea region, aerial seeding of saxaul trees (Haloxylon aphyllum or H. persicum) is a large-scale afforestation technique primarily used to combat desertification and stabilise SDS sources, particularly on the dry bed of the Aral Sea. Scattering seeds from aircraft (including motorised hang gliders, drones, and aeroplanes) enables thousands of hectares of desert to be seeded in a short period of time, creating shrub strips that trap sand and reduce the frequency of emissions.

References and Good Practice Guidance

• National Academies of Sciences Division on Earth, Life Studies, Water Science: Effectiveness and Impacts of Dust Control Measures for Owens Lake, pages 91-96.
• Wilkes Centre for Climate Science and Policy: Dust Mitigation Options and Costs for Great Salt Lake