Updated: Jan 28, 2021
Since the '50s, China has battled with the invading Gobi Desert or ‘yellow dragon’ from the North. In an attempt to halt its advancement, the Chinese government began planting a ‘Great Green Wall’ of trees in 1978. Decades and billions of trees later, the project has been proclaimed a success by the Chinese government, but it has also received criticism and has experienced substantial setbacks illustrating the complexity of undergoing such an extensive afforestation project. With climate change threatening to convert vast swathes of land into desert around the world, similar projects are now taking place elsewhere. For these projects, the pioneering experiment of the Chinese Great Green Wall offers a long-term case study to be learned from when looking to combat desertification.
During the 1950s the young People’s Republic was forced to create useable farmland and living space to accommodate a rapidly growing population. In clearing the land of native vegetation to achieve this, they also compromised the protection from wind erosion and deposition that these natural ecosystems had provided, making these areas vulnerable to desertification (1).
When vegetation is removed from a patch of land, it no longer holds together the soil column, making it more vulnerable to being blown away. Without vegetation, the nutrient-rich topsoil layer is exposed to the elements. When this is removed, it leaves the land barren and infertile. Not only this, when finer particles making up the topsoil are blown into the atmosphere, dust storms form which can travel great distances. Additionally, once the topsoil layer is swept away, coarser particles and sand that has become exposed also get carried by the wind, resulting in more localised sandstorms (2).
To slow the Gobi Desert from invading further, and in an attempt to revert damage largely caused throughout the 50s, the Chinese government began work on the ‘Three-North Shelterbelt Project’. The project, which began in 1978, would involve planting a 4,500 km ‘Great Green Wall’ of trees across China’s Northern border (3). The wall would act as a natural barrier and stop the desert from forcing ecological migrants from their homes. It would also reduce the occurrence of dust/sandstorms (which regularly choked large settlements such as Beijing) and ensure future food security for the country via preservation of farmland. By 2050 (the project’s end date), 100 billion trees will have been planted, and one-tenth of the country dedicated towards tree growth (4).
Figure 1 - The Great Green Wall is projected to be complete by the year 2050. By that point it will cover 88 million acres of land, will stretch approximately 2,800 miles long and be 900 miles wide in places (5,6)
Figure 2 – A sandstorm begins to engulf the city of Kashgar, in North-West China (7)
Around 50 years have passed since the project began, so is there any indication that it is working?
Critical evaluation of the results so far has proven difficult, mostly since the majority of statistics and figures have come from the same state forestry department responsible for planting the trees (8). Many cite methodological inconsistencies and discrepancies as grey areas and reasons to view reported successes as dubious (1).
Those statistics offered by the Chinese government suggest the project has already proved to be a success. By 2014 over 66 billion trees had been planted (4), suggesting they are on track to meet their 100 billion target by 2050. The wall has also reportedly delivered positive outcomes in several key areas. According to China’s state forestry administration, deserts continued to expand from 1994-1999 but between the years 1999-2014, the desert reportedly shrunk. By 2017, China’s deserts were shrinking by more than 2,400 square kilometres per year (1,9). The project has also reportedly decreased sandstorm occurrence by 20% in recent years. Additionally, local temperatures have lowered, soil carbon levels have increased, and vast amounts of carbon have been sequestered (between 1994-2012, an estimated 8.54 Gigatons of CO2 (4)).
Though these statistics should be taken with a pinch of salt, some independent research has produced findings which align with these claims, perhaps lending weight to the official statistics presented. One study conducted in 2018, for example, which involved analysis of satellite data from the US National Oceanic and Atmosphere Administration, found that forest cover changes were consistent with Chinese government statistics (10). In addition to this, the UN has stated that they believe ‘China is making major strides towards combatting desertification’, and that their ‘efforts to halt the Gobi provide a blueprint for tackling desertification’ (11), suggesting overall that they believe the project so far has been a success.
Figure 3 – Two women planting trees for the Chinese Great Green Wall. The Chinese government have created strong incentives which encourage private-sector organisations to restore degraded areas. Farmers and herders also receive subsidies when they carry out restoration work (3,8).
Criticisms and failures
Despite these reported successes, the project also has received criticism, primarily that the project has either focused too much on fast results and/or has lacked sufficient subtlety.
One criticism is that the project concentrates too heavily on planting trees but neglects them once planted. Another is with the project’s ‘blanket planting’ approach which involves indiscriminately planting trees regardless of where they would grow and survive naturally (5). Many believe these two factors contributed towards some of the mass die-offs which have been reported. In 2008, for example, winter storms led to 10% mortality in forest stock planted that year, which led to the world bank urging the project to focus more on quality rather than quantity moving forward (12).
The nature of trees planted has also been criticised, specifically the origin and diversity of species used. Though the project was to occur over a vast period, reportedly local officials wanted to see quick results. Due to this, the majority of trees planted were poplars, selected as they are fast-growing and able to withstand the northern regions’ cold, dry winters (13). These non-native trees, when compared to native shrubs and bushes, use lots of water and therefore are not the best fit when considering the dry, local conditions. “The idea is nice, but it’s kind of foolish to plant trees in a desert” according to Troy Sternberg, a geographer at the University of Oxford, UK (9).
When thirsty poplars get planted, they soak up the limited groundwater available, leaving the land even more arid. One 2019 study concluded that semi-arid areas grew by 33% between 1994-2008 compared to between 1948-1962 (14). Another 2019 study found that arid land in China had increased by around 1.6 million square kilometres (roughly the size of Iran) since 1980 (15). Though this change is likely influenced by a changing climate, non-native poplars sucking up groundwater and reducing run-off to rivers may be exacerbating the problem.
When trees are planted, they reduce the amount of moisture available to local shrubs and grasses, which leads to mortality in these species. The now-dead shrubs and grasses no longer offer structural support to the soil, resulting in soil degradation (5), the prevention of which is one of the projects primary goals. This replacement of local flora with a select few tree species has led to a reduction in biodiversity also, leading to additional problems.
Rather than promoting diverse and stable ecosystems, the project has established vast, unstable monocultures or ‘green deserts’ as some describe them. Monocultures do not possess the functional resilience or stability that natural, diverse systems have; this has led to many questioning the long-term viability of the project (4). The Chinese Great Green wall has already suffered as a result of this. In 2000, one billion trees were killed by softwood-loving anoplophora beetles, who feed on the wood of living trees (16). According to William Wetzel, lead author of a 2016 paper investigating insect pests' love for monocultures "A monoculture is like a buffet for plant-eating insects where every dish is delicious," (17).
Figure 4 - An Asian long-horned beetle, belonging to the higher classification anoplophora. The Asian long-horned beetle has been responsible for significant tree mortalities over the Three-North Shelterbelt Project’s history (18).
Though it has proven difficult to verify official reports from the Three-North Shelterbelt Project, it has undoubtedly been an ambitious and pioneering experiment. Even if the project ends up being a resounding failure, at least it illustrates that expansive top-down afforestation can be implemented. Additionally, it provides a blueprint and a long-term case study which can be learned from and improved upon moving forward.
In 2007, a handful of nations throughout middle Africa formed a coalition who collectively planned to afforest the Sahel region to stop the Sahara in an attempt similar to the Chinese Green Wall initiative (8). Initially, this African Great Green Wall was a failure and received some of the same criticisms as in China: large chunks of the proposed African wall were uninhabited, meaning no one would be there to care for the saplings for example (19). Instead of persisting with planting an actual green wall, the African project adapted into a tree-planting program centred around indigenous land techniques. This new project was named “Africa’s flagship initiative to combat land degradation, desertification and drought” and shifted the focus from forestry to sustainable land and water management. Rather than planting a forest on the edge of the desert, the new ‘metaphysical’ wall would focus on surrounding the Sahara with a wide belt of vegetation, trees and bushes to protect agricultural landscape rather than fixating upon planting a narrow band of trees across the desert in such immediate proximity (19,20).
Though this new and adapted regime is still in its infancy, it has reportedly succeeded in restoring around 5 million hectares of land and has established 200 million drought-resistant trees. According to Chris Rejj, a sustainable land management specialist who has worked for decades in the Sahel, this restoration delivers an additional 500,000 tons of cereal grain a year, enough to feed 2.5 million (20). Mohamed Bakarr, the lead environmental specialist for Global Environment Facility, an organisation that evaluates World Bank projects says, “We moved the vision of the Great Green Wall from one that was impractical to one that was practical” (19).
The extent of success/failure of the Chinese Great Green Wall is largely unknown, however, it is known that the project was not optimal in several aspects. The African Green Wall also exhibited a range of similar problems but was adapted towards a more practical, fluid approach that addresses these issues and shows signs of proving effective as a result.
Over the past 40 years, the earth has lost a third of its arable land to erosion and degradation (1). An estimated 24 billion tonnes of fertile soil and 12 million hectares of productive land are lost annually to desertification (3,9). According to the UN, desertification affects approximately 3 billion worldwide (9), making this a global issue. Those in developing countries, however, who rely more heavily on agriculture for food and income are affected disproportionately. A warming climate looks likely to accelerate the issue moving forward meaning more must be done to combat it.
Though it has had its problems, the Three-North Shelterbelt project established widescale afforestation as a remedy to desertification. That said, criticisms of the project suggest the wall of trees approach to be overly simplistic and sub-optimal. Africa’s flagship initiative trialled this method but subsequently adapted it to become a more fluid system that pays attention to sustainable land and water management. Climate Change is likely to increase the threat of desertification to vast expanses of land in the near future, which may lead to an increase in afforestation projects as a combatant. Where the Chinese Great Green wall was once the prototype to base subsequent afforestation projects on, Africa’s initiative that has shown early signs of encouragement may be the new method to follow, and an example to adapt further to protect those affected by the effects of desertification.