Desert greening

A satellite image of the Sahara, the world's largest hot desert and third largest desert after Antarctica and the Arctic

Desert greening is the process of afforestation or revegetation of deserts for ecological restoration (biodiversity), sustainable farming and forestry, but also for reclamation of natural water systems and other ecological systems that support life. The term "desert greening" is intended to apply to both cold and hot arid and semi-arid deserts (see Köppen climate classification system). It does not apply to ice capped or permafrost regions. It pertains to roughly 32 million square kilometres of land. Deserts span all seven continents of the Earth and make up nearly a fifth of the Earth's landmass, areas that recently have been increasing in size. As some of the deserts expand and global temperatures increase, the different methods of desert greening may provide a potential solution. Planting suitable flora in deserts has a range of environmental benefits from carbon sequestration to providing habitat for native desert fauna to generating employment opportunities to creation of habitable areas for local communities. The prevention of land desertification is one of 17 sustainable development objectives outlined by the United Nations, desert greening is a process that aims to not only combat desertification but to foster an environment where plants can create a sustainable environment for all forms of life while preserving its integrity.

History of modern desert greening

Reforestation of the Kubuqi Desert, China

The practice of recent desert greening can be traced back to the Japanese a horticulture professor, and an agriculturist, Seiei Toyama, who spent 30 years of his life in efforts to green the Kubuqi Desert in China. He authored the text Greening the Deserts: Techniques and Achievements of Two Japanese Agriculturists along with Masao Toyama which was published in 1995. During his time as a professor at Tottori University Toyama was able to revitalize the surrounding sandy dunes into revenue generating farms through his irrigation techniques and knowledge of plant species. After his retirement in 1972, he pursued agricultural projects in China which included the conservation of eroding banks of Yellow River by planting Kudzu vines, introduction of grape growing techniques in Ningxia Huizu Autonomous Region, and his most renowned effort in the Engebei Desert Development, an oasis in the Kubuqi Desert of Inner Mongolia.

Desert greening techniques

When establishing or re-establishing vegetation in desert ecosystems there are many factors to consider before implementing a specific strategy. It is important to account for factors such as the geographical location of the area, amount of annual precipitation, average temperature, soil quality, nutrient availability, native plant and animal life, along with the human impact when aiming to restore a degraded or disrupted desert biome.

Planting

Planting strategies in the desert are different from conventional planting practices, especially in the initial stages. Deserts are regions where annual precipitation amount is considerably less than the evaporation, making it difficult for plants and animals that are not specialized to the biome to survive. One of the ways to ensure the success of the plant life is that prior to being planted in the desert, plants are often grown first in greenhouses allowing for the root system to develop. Often the plant species that are planted in desert regions are those that are capable of surviving on limited water and able to withstand the sun's direct rays. However, deserts also vary, with some being hot and dry and others being semiarid, plants that may survive in a coastal desert might not be able to endure the considerably higher temperatures of hot and dry deserts. Therefore, when planting in deserts as an effort to restore the ecosystem or to create a greener space it is important that the vegetation being planted is suitable to the desert in which it is being planted. Utilizing pioneer desert species like the Acamptopappus shockleyi or Lepidium fremontii which are native to the Mojave Desert, and halophytes such as Salicornia contribute positively to desert greening efforts.

Landscaping and green infrastructure

• Ecoscaping; landscaping methods which reduce evaporation, erosion, consolidation of topsoil, sandstorms, and high temperatures
• Floodwater retention and infiltration (flood control)

Agriculture

• Desert farming, also known as desert agriculture or arid farming, refers to the practice of cultivating and growing crops in arid or desert regions where water scarcity and extreme climatic conditions pose significant challenges to traditional agriculture. Desert farming involves employing various techniques, technologies, and policies to overcome the limitations of arid environments and make agricultural practices feasible. Some common approaches used in desert farming include Water management, Soil improvement, Crop selection, Shade and windbreaks, Greenhouses and controlled environments, and, Desalination and water harvesting. Overall, desert farming aims to maximize the efficient use of water resources, improve soil quality, and select suitable crops to overcome the challenges of arid environments. This allows farmers to cultivate crops and sustain agricultural production in regions traditionally considered inhospitable for farming.
• Greenhouse Cultivation, also known as greenhouse farming or controlled environment agriculture, refers to the practice of cultivating plants within an enclosed structure called a greenhouse. It is a method of crop production that involves creating a controlled environment to optimize plant growth and protect crops from external factors such as extreme weather conditions, pests, and diseases. In a greenhouse, various environmental factors such as temperature, humidity, light intensity, and carbon dioxide levels can be monitored and adjusted to create ideal growing conditions for plants. This is achieved using various technologies such as heating and cooling systems, ventilation, irrigation systems, artificial lighting, and pest control measures. Greenhouses are typically made of transparent materials like glass or plastic, which allow sunlight to enter while trapping heat inside. This helps maintain a warmer temperature compared to the outside environment, extending the growing season and enabling the cultivation of plants that are not naturally suited to the local climate.
• Permaculture in general – harvesting runoff rainwater to grow plant communities polyculture, composting or multitrophic agriculture
• Regenerative agriculture
• Seawater greenhouses and farming, for example, Seawater Foundation or the IBTS Greenhouse

Other

• Prevention of firewood or charcoal use, respectively providing electricity for cooking

Water

Lake Tuendae, an artificial pond at Zzyzx Desert Studies Center in the Mojave Desert

Desert greening is substantially a function of water availability. If sufficient water for irrigation is at hand, any hot, cold, sandy or rocky desert can be greened. Water can be made available through saving, reuse, rainwater harvesting, desalination, or direct use of seawater for salt-loving plants. These different paths have unique features, i.e.: conserving water is a cheap solution. Reuse of treated water and the closing of cycles is the most efficient because closed cycles stand for unlimited and sustainable supply – rainwater management is a decentralized solution and applicable for inland areas – desalination is very secure as long as the primary energy for the operation of the desalination plant is available. Direct use of seawater for seawater agriculture is the most potent, only limited by the need for pumping up the water from sea level.

A novel type of desalination is done with the Sahara Forest Project. This project uses solar stills for the generation of the freshwater. Another novel technique is cloud seeding, either by artificial means or through the action of cloud-seeding bacteria that live on vegetation (e.g. Pseudomonas syringae). Another, "atmospheric water generation" or air to water, uses dehumidification and is used by the military for potable water generation. However this technology uses 200 times more energy than desalination, making it unsuitable for large scale desert greening.

Rainwater Harvesting

Collecting rainwater and storing it in ponds, reservoirs or underground tanks is one of the simplest ways to improve soil moisture content. This helps to increase green cover and crop production in arid areas. Rainwater harvesting is the practice of collecting and storing rainwater for later use. It is an effective method for increasing water availability in arid regions and can contribute to desert greening in several ways such as Increasing soil moisture By collecting and storing rainwater, farmers can provide a reliable water source for their crops, even during periods of low rainfall. This helps to maintain soil moisture levels and improve crop growth in arid regions. Another way it helps is Recharging groundwater. In many arid areas, the groundwater is already depleted, which further exacerbates the aridity. Rainwater harvesting can help replenish the groundwater by allowing the captured rainwater to percolate into the soil and recharge the aquifers. Supporting vegetation growth is also seen as a contibution by providing supplemental water through rainwater harvesting, it becomes possible to grow vegetation and create green cover in arid regions. This can help to combat desertification, reduce soil erosion, and promote biodiversity. Lastly it helps Alleviating water scarcity, In areas with limited access to reliable water sources, rainwater harvesting can serve as a practical and sustainable solution. It reduces dependence on scarce water resources, such as rivers or underground wells, and provides a decentralized water supply system. Overall, rainwater harvesting contributes to desert greening by increasing soil moisture, promoting vegetation growth, and conserving water resources. It is a cost-effective and environmentally friendly technique that can be implemented at various scales, from individual households to large-scale agricultural systems, to make desert areas more productive and sustainable

Water distribution

Once the fresh water or seawater has been attained in centralized systems it must be distributed. This can be done using dug canals or in some instances aqueducts (which are both the least attractive option since they allow much water to be evaporated), troughs (as used in the Keita Project), earthenware piping (semi-open or closed) or even underground systems i.e. qanāt.

Depending on the method of distribution of the water, it can then be provided on different methods to the plants. A costly solution (used only on pipes) is drip irrigation. Other methods are the use of wadis (basically V-shaped ponds dug in the earth) or by simply planting the trees in holes inside/over the water pipe itself. The tree's roots can then suck the water straight from the water pipe (used in qanāt, hydroponics, ...) A similar technique can be done with semi-open pipes (i.e. dug throughs in the Keita Project).

Side effects

The use of water is, however, not always without problems. Desert greening by the Helmand and Arghandab Valley Authority irrigation scheme in Afghanistan significantly reduced the water flowing from the Helmand River into Lake Hamun and this, together with drought, was cited as a key reason for the severe damage to the ecology of Lake Hamun, much of which has degenerated since 1999 from a wetland of international importance into salt flats.

Importance of trees

A main component of desert greening is the planting of trees. Trees store water, inhibit soil erosion through wind, raise water from underlying aquifers, reduce evaporation after a rain, attract animals (and thereby fertility through feces), and they can cause more rain to fall (by temperature reduction and other effects), if the planted area is large enough.

All of the effects beneficial for desert-greening which trees offer can also be provided by buildings. Shading by buildings is an example for a passive effect, the pumping up of water from aquifers an example for an active effect achieved with buildings technology. An example for a building designed to offer all of the beneficial effects of natural forests in the desert is the IBTS Greenhouse.

Examples

Asia

China's Green Great Wall Program

The history of modern desert greening in Asia is similar to that of Africa, with initiatives primarily focused on reducing desertification and promoting sustainable land management practices. However, the challenges faced in Asia are varied, and the solutions have been tailored to meet specific needs. One of the earliest and most notable examples of desert greening in Asia occurred in China. In the 1970s, China launched the "Green Great Wall" program, aimed at planting trees along the border of the Gobi Desert to halt its expansion. The program involved planting over 100 billion trees across a thousand miles of desert within a decade. The initiative was successful in reducing sandstorms and increasing rainfall in the region, and the program has since been expanded to other parts of China. In the Middle East, countries like Israel have been at the forefront of desert greening initiatives. Since its establishment in 1948, Israel has made significant progress in greening the Negev Desert. Initiatives include the establishment of research and development centers for desert agriculture, the introduction of drip irrigation techniques, and the use of treated wastewater for irrigation. In other parts of the world, such as India and Pakistan, desert greening initiatives have focused on afforestation and soil conservation. These initiatives involve planting trees, shrubs, and grasses to hold the soil in place, prevent erosion, and improve water retention. Overall, the history of modern desert greening in Asia reflects the need to address environmental challenges such as desertification and promote sustainable land management practices. These initiatives have often been successful in addressing these challenges and improving the livelihoods of people in arid regions.

China

Reversing desertification of Mu Us Desert west of Yulin, Shaanxi. 1985 (above) and 2021 situation.

Main article: Great Green Wall (China)

The Three-North Shelter Forest Program, also nicknamed the "Great Green Wall", is a series of windbreaking forests in China designed to hold back the expansion of the Gobi Desert and reduce the incidence of dust storms that have long caused problems for northern China, as well as also providing timber to the local population. The program started in 1978 with the proposed end result of raising northern China's forested area from 5 to 15 percent, and is planned to be completed around 2050, at which point it will be 4,500 km (2,800 mi) long. In 2008, winter storms destroyed 10% of the new forest stock, causing the World Bank to advise China to focus more on quality rather than quantity in its stock species.

Geat Green Wall Project

As of 2009, China's planted forest covered more than 500,000 km² (190,000 sq mi), increasing tree coverage from 12% to 18%. It is the largest artificial forest in the world. According to Foreign Affairs, the program successfully transitioned the economic model in the Gobi Desert region from ecologically harmful industrial farming and pastoralism to beneficial ecotourism, fruticulture and forestry. In 2018, United States' National Oceanic and Atmospheric Administration found the increase in forest coverage observed by satellites is consistent with the Chinese government data. According to Shixiong Cao, an ecologist at Beijing Forestry University, the Chinese Government recognized the water shortage problems in arid regions and changed the approach towards vegetation with lower water requirements. Zhang Jianlong, head of the Forestry Department, told the media that the goal was to sustain the health of vegetation and choose suitable plant species and irrigation techniques.

According to BBC News report in 2020, China's tree plantation programs resulted in significant carbon fixation and helped mitigated climate change, and the benefit was underestimated by previous research. The program also reversed the desertification of the Gobi desert, which grew 10,000 km² (3,900 sq mi) per year in the 1980s, but had shrunk by more than 2,000 km² (770 sq mi) in 2022.

India

The soil of the Thar Desert in India remains dry for much of the year and is prone to soil erosion. High speed winds blow soil from the desert, depositing some on neighboring fertile lands, and causing shifting sand dunes within the desert, which buries fences and blocks roads and railway tracks. A permanent solution to this problem of shifting sand dunes can be provided by planting appropriate species on the dunes to prevent further shifting and planting windbreaks and shelterbelts. These solutions also provide protection from hot or cold and desiccating winds and the invasion of sand. The Rajasthan Canal system in India is the major irrigation scheme of the Thar Desert and is intended to reclaim it and to check spreading of the desert to fertile areas.

Prevention of shifting sand dunes is accomplished through plantations of Vachellia tortilis near Laxmangarh town. There are few local tree species suitable for planting in the desert region and these are slow growing. The introduction of exotic tree species in the desert for plantation has become necessary. Many species of Eucalyptus, Acacia, Cassia and other genera from Israel, Australia, US, Russia, Zimbabwe, Chile, Peru, and Sudan have been tried in the Thar Desert. Vachellia tortilis has proved to be the most promising species for desert greening. The jojoba is another promising species of economic value which has been found suitable for planting in these areas.

Africa

Main article: Great Green Wall (Africa)

Modern desert greening in Africa is a relatively recent phenomenon and was primarily initiated in the 1950s and 1960s. The initiative was largely driven by a desire to combat desertification, the process by which fertile land becomes barren and unsuitable for farming, across the continent. One of the earliest and most notable examples of desert greening in Africa occurred in Algeria. In the 1950s, the Algerian government launched an ambitious program to transform over 20,000 square kilometers of arid land into productive agricultural land. This project involved the construction of dams, wells, and irrigation networks, as well as the introduction of modern farming techniques and seed varieties. The program was part of a broader effort to address food insecurity and improve livelihoods in rural areas. In the following decades, similar projects were undertaken in other countries, such as Mali, Niger, and Senegal. These initiatives focused on promoting sustainable agriculture and land management practices, as well as reforestation and the protection of natural ecosystems. Some of the key strategies employed included the use of drought-resistant crops, the introduction of agroforestry techniques, and the establishment of community-based management systems. In recent years, desert greening efforts have also been boosted by the development of renewable energy technologies, such as solar and wind power. These technologies provide a sustainable source of energy for desert regions, which can be used to power irrigation systems and other farming equipment. Greening projects that integrate renewable energy solutions are often more effective and cost-efficient in the long run. Overall, modern desert greening in Africa has made significant progress in reducing the impact of desertification and improving the sustainability of agriculture and natural resource management in arid areas. However, many challenges remain, such as lack of funding, political instability, and climate change. As such, ongoing research and development of innovative strategies, including the integration of new technologies, will be essential for continued success in this area.

The "Great Green Wall of the Sahara and the Sahel" is a project adopted by the African Union in 2007, initially conceived as a way to combat desertification in the Sahel region and hold back expansion of the Sahara Desert by planting a wall of trees stretching across the entire Sahel from Djibouti City to Dakar. The original dimensions of the "wall" were slated to be 15 km (9.3 mi) wide and 7,775 km (4,831 mi) long, but the program has expanded to encompass nations in both North and West Africa. The modern green wall has since evolved into a program promoting water harvesting techniques, greenery protection and improving indigenous land use techniques, aimed at creating a mosaic of green and productive landscapes across North Africa. The ongoing goal of the project is to restore 100 million hectares of degraded land and capture 250 million tonnes of carbon dioxide, and create 10 million jobs in the process all by 2030.

As of March 2019, 15 per cent of the wall was complete with significant gains made in Nigeria, Senegal and Ethiopia. In Senegal, over 11 million trees had been planted. Nigeria has restored 4,900,000 ha (12,000,000 acres; 49,000 km²) of degraded land, and Ethiopia has reclaimed 15,000,000 ha (37,000,000 acres; 150,000 km²). A report commissioned by the United Nations Convention to Combat Desertification (UNCCD) was published on September 7, 2020, that the Great Green Wall had only covered 4% of the planned area, with only 4,000,000 ha (9,900,000 acres; 40,000 km²) planted. Ethiopia has had the most success with 5.5 billion seedlings planted, but Chad has only planted 1.1 million. Doubt was also raised over the survival rate of the 12 million trees planted in Senegal.

In January 2021, the project received a boost at the One Planet Summit, where its partners pledged 14.3 billion USD to launch the Great Green Wall Accelerator, aimed at facilitating the collaboration and coordination among donors and involved stakeholders across 11 countries. In September 2021, the French Development Agency estimated that 20 million hectares have been restored and 350,000 jobs have been created. According to the second edition of the Global Land Outlook' published by the UNCCD in April 2022, one reason the project has experienced implementation challenges is the political risk associated with investing in more fragile nations as well as the fact that many "GGW projects generate low economic returns compared to the significant environmental and social benefits accrued that often have little or no market value". Furthermore, international donors seem to favor investing in more stable nations, picking and choosing which projects they will fund, and leaving nations with less stable governments behind.

Australia

Australia is the world's driest inhabited continent, with a significant portion covered by arid or semi-arid deserts. Desert greening refers to the process of ecosystem restoration and re-vegetation in desert areas to combat desertification and enhance biodiversity. In recent years, there have been various efforts and initiatives focused on desert greening in Australia. One notable example is the "Great Green Wall" project, inspired by similar initiatives in Africa. The Great Green Wall aims to create a vegetation barrier of local native plants across Australia's east coast to prevent desertification and erosion. Another approach to desert greening in Australia involves the use of regenerative farming and land management techniques. These techniques aim to restore degraded soils and improve water retention, which can support the growth of vegetation and increase biodiversity. Additionally, there are ongoing research and development projects that explore innovative techniques to facilitate desert greening, such as solar-powered desalination plants, drought-resistant crop varieties, and the use of native plant species that can thrive in arid environments. It's important to note that the success of desert greening initiatives depends on various factors, including local climate conditions, access to water resources, suitable plant species, and sustainable land management practices.

Sundrop Farms launched a greenhouse in 2016 to produce 15,000 tonnes of tomatoes using only desert soil and desalinated water piped from Spencer Gulf.

See also

• Afforestation
• Al Baydha Project
• Algerian Green Dam
• Arid Forest Research Institute
• Conquest of the desert exhibition
• Ecological engineering
• Fertilizer tree
• Global warming
• Great Green Wall (Africa) and Great Green Wall (China)
• Oasification
• Restoration ecology
• United Nations Convention to Combat Desertification
• Wadi Rum Consultancy
• Water crisis

External links

• "How to green the desert and reverse climate change" Allan Savory, TED talk, February 2013.
• Greening the Desert II – Final
• Animation of Desert Greening in Egypt with the IBTS Greenhouse LivingDesert Group