Deserts cover 30.6 million km² on Earth. This is 20% of the land surface of the planet. Antarctica has almost half of the total desert areas in the world. Next come the Sahara, the Arabian Desert, the Libyan Desert, the Australian Desert, the Gobi Desert (Asia), the Kalahari (South Africa), the Karakum (Asia), the Taklamakan (Asia), the Namib ( South Africa).
The so-called arid zones cover a total of 31% of the land surfaces.
Propensity of the deserts
We can fight against the gradual spread of deserts by stopping overexploitation, deforestation, limiting the lack of water, clearing by livestock. It is necessary to understand how the deserts are created, how the dune highways form, where do they go.
The Chinese have found that by putting 12 inches high nets in sandy deserts with a shape of zigzag, separated by 3-6 feets on several square miles, storms were stopped or spread less easily.
There are several solutions. First of all the stone bed shaped like a chinese hat 20 inches under each shrub. The straw bed with heaps of straw mixed with earth or sand. The work to consolidate the soil is the most exhausting and the longest in reforestation.
By planting trees directly in the soil of sandy areas, there is a 50% chance of survival. By planting the trees by making a hole with water under high pressure, the chances of survival increase to 85%.
Trees can also become ill and they can also spread their disease to other trees, giving birth to epidemics. These can be slowed by the establishment of other tree species.
It is obviously impossible to water hundreds of square miles to feed the newly planted shrubs. Rain can be forced by using silver iodide spreads (which replaced liquid nitrogen). Rain makers can also work from the ground with ground-to-air cannons. Subsequently, the created forest will naturally capture the humidity of the air and will itself create a zone of condensation by evapotranspiration with the formation of clouds. A virtuous cycle will thus be realized.
We can also consider the use and recycling of wastewater to ensure the growth of trees.
The relief allows the water runoff, the infiltration of water into the soil, a dynamic groundwater table. The relief can block the clouds that will precipitate. The creation of hills and mountains is too expensive. We could think about designing mountain skeletons and covering them with the latest concrete techniques. It can even snow in height on the mountains, there can be the formation of glaciers, lakes, torrents, rivers of waterfalls.
The presence or addition of relief (in a distant future) is an asset for the reforestation of an arid zone.
The Chinese have more and more sandstorms, the meeting of deserts increases the possibility of this type of disaster. Beijing receives 1.3 million tons of sand every year. So they invested a lot in reforestation to reduce deserts. But also in the natural reconstruction of dry lakes. The liquid surfaces can also stop these storms. They have already reforested the equivalent of the surface of the United Kingdom.
The fact that China has embarked on the reforestation of its desert lands is good news for the world, solutions to the problems of the deserts will evolve more quickly. The government is doing everything to optimize these new green zones.
With more than a thousand people, they fixed the sand by making squares of straws. But also plastic nets to block the sandstorms, much faster to pose than straw squares and more economical. They chose “yang shu” as tree species, “soh zso”, and pines “shang zsan”. They deposited cyanobacteria for the development of lichen.
This reforestation program was launched 39 years ago.
Jadav Payeng grew more than 550 hectares of forest on an island covered with sand. Since the place has been adopted by several animals, including a species of endangered tiger that has even reproduced itself. The Molai Forest is located on the Brahmaputra River near Jorhat. He started growing it 38 years ago.
He first planted bamboos and then real trees. He added ants to change the properties of the soil. He embarked on this operation after discovering dozens of dead snakes on this former sandbar for lack of food.
In Burkina Faso
Yacouba Sawadogo used assisted natural regeneration to revitalize the desert of the village of Gourga, in the Yatenga region. In 37 years he has been able to create a plant area of 40 hectares in an environment hostile to plants. To achieve this result he applied the Zai, a technique that consists of filling organic manure in small holes that will retain water. He also uses a string of stones over a fence to prevent runoff of water. Soil erosion is avoided, and moisture is conserved during periods of drought. More than sixty plants have colonized this arid land.
This technique is inexpensive and simple to implement. It requires however a lot of time and energy.
Thanks to the use of partially treated wastewater, Egypt was able to grow a 200-hectare Serapium forest in the middle of the desert in Ismailia, a two-hour drive from Cairo. The program was realized over 25 years. The trees now have very favorable conditions, growing four times faster than in Europe. The water comes from the drainage basin of the nearest city. Phosphates and nitrogen allow plants to grow in an optimal manner. These elements are natural fertilizers par excellence.
These trees need only 15 years to be cut, that is to say to reach the minimum size of cut, against 60 years in Europe. By exploiting the 7 billion cubic meters of wastewater in the country, Egypt hopes to eventually reforest most of its desert lands. The forest also has eucalyptus, pines. It recycles the water.
Sarah Toumi, known as the acacia lady, is trying to launch a momentum to green the country for 5 years by pushing women to participate and indirectly get out of the straitjacket in which they find themselves, by working a little every day. But also farmers despite a conservatism of society. It involves planting trees to improve eroding soils, in this case acacia trees and fruit trees adapted to the climate, legumes such as moringa. To create compost from palm waste with vegetable and organic matter. Make hedges to protect the oasis. Set up distribution channels to sell the crop products.
She plans to plant a million trees by the end of 2018.
Australia is severely affected by the desertification of its lands, due in part to overexploitation of livestock farming.
Mitchell grass is a grass that allows farmers to grow green again where the land seemed dead. It was discovered by Scottish explorer Thomas Mitchell. It grows easily on clay soils that are deemed to be ungrateful. It stores energy through a multitude of rhizomes full of starchy foods that allow it to relive after extreme heat. Each plant has a lifespan of 30 to 35 years.
Dr. David Phelps advises farmers on how to implement it on their land and when to reinstate cows and sheep.
Farmer Bob Purvis from Atartinga, 200 kilometres north of Alice Springs, noticed when making earthen walls, the wind was stopped and that the grass shoots could then penetrate the soil which in addition to being very poor is also hard as stone in his region, rather than being swept to dry off a little further. He tested 60 species of plants other than native seeds that had all practically disappeared. Only US Buffel grass and Blue Panic are resistant to the soil and climate conditions. He also manages a stock of livestock which represents 10% of the average recommended by the government for the size of his land. It has fewer cows but they grow more than those in the other farms and much faster. They are sold at premium prices. And he has less need to invest in fodder.
In the world
Algeria, Mali, Tunisia, Libya, Mongolia or Egypt would have a completely different face without the deserts but with more forests.
It would be good to do as in China and force every citizen of the world to plant 4-5 trees each year. It is enough to recover young plants that have little chance of growing because they are too close to other trees and plant them near the forests, so they spread faster.