Desert greening

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. Desert greening has the potential to help solve global water, energy, and food crises. It pertains to roughly 32 million square kilometres of land.
Revitalizing arid landscapes offers numerous substantial advantages that have a positive impact on the environment, humans, and wildlife. These benefits encompass carbon sequestration, drawing in tourists, generating employment opportunities for local communities, stimulating natural rainfall patterns, and potentially luring back animal species that had migrated due to desertification. The prevention of land desertification is among the 17 sustainable development objectives outlined by the United Nations, a goal that can significantly advance the sustainable progress of desert greening. At present, tree planting stands out as the most efficient means to attain this objective. The process of greening a desert involves the transformation of arid landscapes into fertile, verdant lands with a rich variety of trees and plant species, creating a suitable environment for both humans and animals. It's a systematic approach to afforestation, aimed at converting degraded lands into economically valuable forests that can serve various purposes, including agriculture, carbon offset initiatives, research facilities, timber production, and ecotourism.
Planting trees plays a pivotal role in the advancement of desert greening. Nonetheless, the ongoing tree-planting endeavors are marred by certain shortcomings, such as limited effectiveness, labor-intensive requirements, challenging environmental conditions, and a low survival rate for young trees. Successful desert greening necessitates the establishment of a proficient management team with the necessary technical expertise, the implementation of water retention techniques such as sub-surface drip irrigation, the creation of high-quality nurseries capable of producing drought-resistant seedlings of economically valuable trees and crops, a commitment to environmental sustainability, and measures to control excessive grazing by nomadic herders. These measures are essential to ensure that the green belt created is not misused or subject to degradation.
Methods
Environmental remediation and ecoforestry
Planting trees (pioneer species) and salt-loving plants (halophytes), such as Salicornia
Planting trees augmented by dew and rain harvesting technologies like the Groasis Waterboxx
Regeneration of salty, polluted, or degenerated soils
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 based on fossil groundwater, although not being sustainable
Farmer-managed natural regeneration
Greenhouse agriculture
Holistic management
Inland mariculture
Managed intensive rotational grazing
Permaculture in general – harvesting runoff rainwater to grow plant communities polyculture, composting or multitrophic agriculture
Prevention of overgrazing
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
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.
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
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 long. The fourth phase of the project started in 2003 and has two parts: the use of aerial seeding to cover wide swathes of land where the soil is less arid, and the offering of cash incentives to farmers to plant trees and shrubs in more arid areas. A $1.2 billion oversight system (including mapping and surveillance databases) is also to be implemented. A belt of sand-tolerant vegetation arranged in checkerboard patterns are planted to stabilize the sand dunes, and a gravel platform will be next to the vegetation to hold down sand and encourage a soil crust to form. 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.
As of 2009, China's planted forest covered more than , 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 per year in the 1980s, but had shrunk by more than 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
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 wide and 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 of degraded land, and Ethiopia has reclaimed . 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 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 of 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
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.
Advantages of Greening the Desert
Carbon sequestration: This mechanism involves the extraction of carbon dioxide from the atmosphere or its removal from the initial emission source, subsequently storing it in various places like green plants, soil, oceans, wood, and more. Carbon dioxide is a significant greenhouse gas that contributes to global warming. The primary sources responsible for the rising levels of carbon dioxide in the atmosphere encompass the combustion of fossil fuels and the extensive deforestation for timber and firewood, a widespread practice in many developing nations.
Protection against sand and dust storms: After successfully afforesting desert regions with trees and various vegetation, a significant reduction in the threat of sand and dust storms will occur. This is because the trees and plants in the area will effectively bind soil particles together, preventing them from being carried away by strong winds, which would otherwise transport sand and dust particles from their original location to other areas. The tree cover, acting as a shelter belt, serves as a windbreak, thus alleviating the impact of sand and dust storms.
Natural rainfall creation: The verdant forest established through desert greening plays a crucial role in natural rainfall generation. When precipitation occurs, a portion of it infiltrates the soil, where it is taken up by plants through their root systems. These plants subsequently release the absorbed water into the atmosphere through transpiration, contributing to the formation of clouds, and eventually leading to more rainfall. This cycle ensures a consistent water supply for crops cultivated in this environment, thus supporting agricultural activities and ensuring food availability for those whose livelihoods rely on farming.
Reduction in evaporation: Elevated temperatures pose a significant challenge in desert regions. However, desert areas that have been effectively afforested with extensive lines of trees do not experience this issue. These trees create a canopy that shields the soil from direct exposure to sunlight, thereby diminishing the rate at which water evaporates from the soil into the atmosphere.
Ecotourism:''' The process of greening desert areas will revive these once barren environments, promoting the establishment of recreational parks, the construction of roads, hotels, and other essential infrastructure. This, in turn, will create numerous job opportunities, enticing those who had departed due to desertification to return. The jobs generated will contribute to revenue generation through the sale of local souvenirs and handicrafts, transportation fares for taxi cab and domestic airline operators, income for restaurant owners and fast-food vendors, and fees for tourist guides, among others. This multifaceted economic activity will undoubtedly alleviate the problem of unemployment, which is a significant concern in many developing countries, and help to maintain low crime rates.
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
References
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
Greening
Desertification
Ecosystems
Land reclamation