Surprise! satellites counted more trees west of the Sahara and the Sahel than previously thought

Data collected by satellites enabled researchers to inventory trees west of the Sahara and the Sahel with a level of detail never equaled over such a large area. And against all odds, they listed more than they had imagined. Soon, thanks to artificial intelligence, the location and size of every tree on Earth can be mapped.

You will also be interested

[EN VIDÉO] Extreme planet: the huarango, a thousand-year-old tree threatened with extinction
This new extract from Peru, Planète Extrême, takes us to the discovery of a very particular tree: the huarango. Accustomed to the lack of water and the hot desert climate, it is now threatened. Discover, in this documentary produced by French Connection Films, one of the most amazing trees in Peru.

Southern Sahara and the Sahel are home to more thantrees previously thought, playing a “crucial role” for the biodiversity and the lives of populations, according to a study published Wednesday in the revue Nature.

The international team of researchers has developed a pattern recognition program by artificial intelligence for count trees with a plant surface of more than three square meters, from more than 11,000 images satellite High Definition.

Over an area of ​​1.3 million km2 (i.e. two and a half times the area of ​​metropolitan France) in the south of the Sahara, the Sahelian strip (semi-arid zone south of desert) and sub-humid areas in Africa from the west, they were able to count more than 1.8 billion trees. Or an average of 13.4 trees per hectare, with a median plant cover of 12 m2.

An astonishing density of trees

This vegetation, certainly sparse, ” plays a crucial role for biodiversity and forecosystem as storage of carbone, food resources and shelter for human and animal populations, note the researchers. Although the total vegetation cover is low, the relatively high density of isolated trees challenges the prevailing idea of desertification dry areas, and even the desert offers a surprising density of trees ».

The density increases as it descends towards the wetter zones in the South, from 0.7 trees per hectare in the “hyper-arid” zones, to 9.9 in the arid zone, 30.1 in the semi-arid zone 47 trees per hectare in a sub-humid zone.

AI to identify every tree on Earth

In addition to this census, the study offers a new method for studying the presence of trees outside dense forest areas, and in particular their possible role in matter of climate change and therefore potentially poverty, through their contribution to the agricultural systems, the authors say.

« This kind of data is very important to establish a base. And in two or ten years, we could repeat the study to see if efforts to revitalize [la végétation] are effective “, Explained in a press release one of the researchers, Jesse Meyer, of the American space agency. Nasa.

The AI ​​technique used further suggests “ that it will soon be possible, within certain limits, to map the location and size of all trees, [une connaissance] fundamental to our understanding ofecology worldwide Said Niall P. Hanan and Julius Anchang of the American University of New Mexico, in an analysis of the study commissioned and published by Nature.

This video allows you to see the scientific work. © NASA

Interested in what you just read?


How Macron is waging his secret wars

INVESTIGATION – Since his election, the President has launched increasingly offensive military operations and authorizes serial “neutralizations”. Our collaborator Vincent Nouzille investigated this top secret facet of presidential action.

By Vincent Nouzille

Emmanuel Macron, May 14, 2019, during the tribute ceremony to the two special forces soldiers who died on May 10 during an operation in Burkina Faso.
Emmanuel Macron, May 14, 2019, during the tribute ceremony to the two special forces soldiers who died on May 10 during an operation in Burkina Faso. Jacques Witt / SIPA

It was a summery, but chilling defense council. On August 11, 2020, from Fort Brégançon, President Emmanuel Macron meets by videoconference with his Prime Minister Jean Castex, the royal ministers, the chief of staff of the armed forces and the bosses of the intelligence services. The agenda is serious, mourning the murder, on August 9, of eight people, two Nigerians and six French members of the NGO Acted, in the Kouré reserve, near Niamey, in Niger. A real massacre committed by men arriving on motorcycles.

Until now, this area still seemed protected from repeated attacks by jihadist groups who have spread their guerrillas in several countries of the Sahel. The 5,100 French soldiers of Operation Barkhane have increased for six months the lightning operations aimed at weakening the two main rival nebulae, the GSIM (Support Group for Islam and Muslims), linked to al-Qaida, and the EIGS (Islamic State in the Great Sahara), affiliated with Daesh, in particular

This article is for subscribers only. You have 94% left to discover.

Subscribe: 1 € the first month

Cancellable at any time


a fortress inspired by the military genius of Vauban to stop Islamist terrorism

SEEN FROM ELSEWHERE – On the border with Niger, France has built an outpost considered impregnable.


Labbezanga, where an outpost considered impregnable has been built, is located 200 kilometers from the Gao military base, where more than 5,000 soldiers from Operation “Barkhane” are deployed.
Labbezanga, where an outpost considered impregnable has been built, is located 200 kilometers from the Gao military base, where more than 5,000 soldiers from Operation “Barkhane” are deployed. BENOIT TESSIER / REUTERS

Par Pietro Del Re, correspondant to Bamako (The Republic)

To defend the village of Labbezanga, located on the border between Mali and Niger, from jihadist offensives, the French have just built an outpost considered impregnable. To do this, they were inspired by the fortifications built by their ancestors during the Renaissance period, including the Citadel of Besançon, the Tour Vauban (initially Tour de Camaret) or the Fort Carré d’Antibes, buildings which are all listed UNESCO World Heritage Site and were all built by France’s most famous military engineer, the Marquis Sébastien Le Prestre de Vauban. In Labbezanga, this return to the past has a specific objective: to resist the Islamist phalanges in a portion of the desert where militiamen affiliated with Al-Qaeda and the Islamic State swarm, an area located 200 kilometers from the Gao military base, where the more than 5000 soldiers of Operation “Barkhane”, sent by Paris are deployed

This article is for subscribers only. You have 82% left to discover.

Subscribe: 1 € the first month

Can be canceled at any time


In the Sahel, fear of the return of child soldiers

DECRYPTION – Operation Barkhane is concerned about the recruitment of minors by terrorist groups.

A French army soldier patrols in northern Burkina Faso last November during Operation Barkhane.
A French army soldier patrols in northern Burkina Faso last November during Operation Barkhane. MICHELE CATTANI / AFP

Operation Barkhane’s latest offensive against terrorist groups in the Sahel has borne fruit, but a long-term threat looms. The Islamic State in the Grand Sahara, designated as the main enemy since January, suffered severe losses, according to the French general staff. “Its human and material capacities have been greatly reduced”, welcomed General Facon, commander of the Barkhane force, Thursday, during an exchange with the press. But “The enemy has hardened. He no longer hesitates to resort to child soldiers. The latter are indoctrinated and trained in the handling of weapons ”, he warned.

“This abject exploitation puts us in difficulty”, agreed General Facon. Child soldiers are nothing new. In 2013 already, al-Qaida was pushing young recruits on the Sahelian terrain. Their presence in the terrorist ranks, intended to divert the vigilance of the soldiers or to serve as a fact of human shield, constitutes a challenge for the Western armies. Each

This article is for subscribers only. You still have 75% to discover.

Subscribe: € 1 for 2 months

Cancelable at any time


The Civil Guard leads a training project in the Sahel | International

Without reaching the level of involvement of France, Spain is one of the European countries that most participates in the Sahel’s military operations. The almost 300 Spanish soldiers who make up the mission to form the Malian Army – EUTM Mali, the main EU mission in the region – represent half of those who make it up. To this number are added another 50 responsible for providing air support from Senegal to the activities carried out by France and the EU in Mali. Lastly, the Civil Guard is leading an anti-terrorist training project for the Sahel countries that make up the G-5.

The volume of Spanish soldiers involved and the interest in appeasing a region so troubled and so close to Spain have motivated the Spanish Army to twice assume command of the EU mission, which dates from 2013. The last time was between January and November 2018. Spanish forces are present at the bases in Bamako, the capital, and Koulikoro, about 60 kilometers away. Far from there – in Senegal, with a much more stable scenario than Mali -, fifty hundred soldiers offer support for the air movements of all these operations.

Also training is the operation designed by Spain, with European funds, to improve the fight against terrorism in the Sahel. This is GAR-SI Sahel, an initiative led by the Civil Guard – and also involving France, Portugal and Italy – to create rapid-action units in Mauritania, Mali, Niger, Burkina Faso, Chad and Senegal. In Mali there is a deputy coordinating commander of the project and two others responsible in Mauritania and Niger, as well as three guards in Niger and another three in Mali, according to the Civil Guard. A part of the training is also done in Spain. The project, which attempts to replicate Spanish practices, is endowed with 66 million euros and has the potential to grow.

Due to the exceptional circumstances, EL PAÍS is offering all its digital content for free. Information regarding the coronavirus will remain open as long as the severity of the crisis persists. Dozens of journalists work tirelessly to bring you the most rigorous coverage and fulfill your public service mission.

If you want to support our journalism you can do it here for 1 euro the first month (from June 10 euros).

Subscribe to the facts.



Jihadism grows strong in the Sahel | International

Dozens of terrorists aboard pickups and motorcycles pounced last Thursday, around noon, on the Chinegódar military camp in Niger. The skirmish ended with 166 dead, 89 Nigerian soldiers and 77 assailants, making it the worst jihadist attack suffered by this country in its entire history. This episode is but the bloody epilogue to the deadliest year in the Western Sahel since the start of the crisis in 2012. According to data compiled by the International Crisis Group (ICG), 4,779 people were killed in Mali, Niger and Burkina Faso in 2019. Faso, 86% more than in 2018. Jihadist violence and extrajudicial killings of civilians by militias and paramilitary units are spreading throughout the region.

When the Tuareg rebels in northern Mali took up arms in January 2012 with the aim of creating an independent state, no one could have predicted that eight years later the entire region would be shaken by violence that has claimed no less than 12,824 lives. in this period. Its alliance of circumstances with three terrorist groups operating in the area, Ansar Dine, Al-Qaeda of the Islamic Maghreb (AQMI) and the Movement for the Uniqueness of Jihad in West Africa (Muyao), sparked a conflict that neither successive military operations Neither the French (Serval and Barkhane) nor the creation of the Sahel G5, the underinformed force made up of the Armies of Niger, Chad, Mauritania, Burkina Faso and Mali, have been able to stop. Given the increase in jihadist attacks, the French president, Emmanuel Macron, is meeting on Monday the presidents of those five countries at a summit in Pau (south-western France) to address the issue.

In parallel to the increase in attacks and deaths, growing anti-French sentiment is spreading throughout the region on the back of groups that define themselves as anti-colonialists. If in 2013 the Gallic troops of Operation Serval were received as heroes in the streets of Gao and Timbuktu, nowadays their presence is increasingly contested. Anti-government protests in Bamako chant slogans against “the occupying army” and in Ouagadougou (Burkina Faso), citizen movements do not hide their discomfort at the military interventions of Barkhane, who travels the roads in the north of the country in search of suspected terrorists without any impediment.

Burkina Faso is the best example of the situation. In 2019, it became the fourth African country in the number of victims of violence, going from 303 people killed in 2018 to 2,189 last year, just one step behind such consolidated conflicts as those of Nigeria, Somalia and the Democratic Republic of the Congo and ahead of Libya, according to the ICG. Burkina Faso has even surpassed Mali (1,870 deaths in 2019) and Niger (720 fatalities). The most worrying is the trend. December last year was the month with the most murders in terrorist attacks in the three countries, including the jihadist offensive against the Nigerian headquarters of Inates, which killed 71 soldiers.

In addition to Diffa, in the extreme east of Niger, where Boko Haram continues to be active, the so-called three-border area is, today, the main epicenter of this violence. From the Malian regions of Mopti and Gao, the jihadist presence has spread to the Sahel, Central-North, East and North regions (Burkina Faso) and to Tilaberi, in western Niger. It is here, in the enormous Sahelian expanses, where three terrorist groups move like a fish in the water supported by the porosity of the borders, the incapacity of armies in frank withdrawal and the discomfort, sometimes turned into complicity with the radicals, of communities plunged into poverty and abandoned to their fate who also suffer the violent repression of the State.

On the Malian side of the border, the most active is the Muslim and Islam Support Group (JNIM), the terrorist coalition resulting from the union of Al Murabitún with Mojtar Belmojtar (known as Mr. Marlboro or El Tuerto), Ansar Dine led by the Tuareg Iyad Ag Ghali and the Macina Liberation Front of the preacher Fulani Amadou Koufa. The JNIM maintains links with Al Qaeda. In 2016 Ansarul Islam arises in the north of Burkina Faso, led by Malam Dicko at the time and is now believed to be by his brother Jafar Dicko after the death of the former. Finally, there is the Islamic State of the Great Sahara (EIGS) under the command of Abu Walid Al Saharaui, responsible for the main attacks in Niger but also capable of striking in the other two countries.

In front of them, in addition to the national armies, Operation French Barkhane, the most numerous of all that this country maintains abroad, has some 4,500 troops on the ground. They have been joined by a British detachment with 100 soldiers and three helicopters and 70 soldiers and two other Danish helicopters, reports AFP. As a peacekeeping force, the UN maintains some 15,000 blue helmets in Mali, from countries such as Chad, Bangladesh, Burkina Faso, Senegal, Egypt, Togo, Niger, China or Germany, which are constantly harassed by armed groups that have caused them about 200 casualties.

The G5 of the Sahel was born in November 2015 with the intention of deploying some 5,000 soldiers on the ground, but it has been operational since 2017, it has not reached that figure and it has financing problems, since of the 400 million euros it has only received 300 last year. In addition, its troops have been accused of human rights violations in Mali, specifically against the Fulani community. Finally, there is the European training mission for the Malian Army and the G5, the EUTM, which has just over 600 soldiers and is the only one in which Spain participates, although without engaging in combat.


France and G5 Sahel leaders close ranks to curb jihadism | International

France and the five countries of the Sahel strip closed ranks on Monday before the jihadist push in the region and the outbreaks of anti-French sentiment after seven years of uncertain anti-terrorism mission. At a summit in Pau (department of the Atlantic Pyrenees), President Emmanuel Macron and his so-called G5 counterparts: Mali, Chad, Niger, Burkina Faso and Mauritania acknowledged the recent failures of the current strategy. The leaders agreed to strengthen military coordination, specify the scope of the operation and expand it to other European countries.

“The increase in attacks, the destruction we suffered and the unprecedented humanitarian crisis have challenged us. We must move to a higher stage in the coordination of our operations. The results are below expectations,” said Roch Marc Christian Kaboré , President of Burkina Faso, at a press conference with Macron and Mali’s leaders, Ibrahim Boubacar Keïta; from Mauritania, Mohamed Ould Cheikh El Ghazouani; from Niger, Mahamadou Issoufou; and from Chad, Idriss Déby Itno. “We need rapid military results,” he added.

The objective in Pau was twofold. First, political: to renew the commitment of the five Sahel countries to the French presence and to make them clear that France is there at their request and not with any interventionist zeal. “Do they want our presence? And do they need us? ”Macron reacted in December to protests and statements contrary to the French presence. The message, on the eve of the summit, had the tone of a veiled threat: either the partners were clearing up these concerns, or Paris could withdraw its military.

The summit gave a clear response to this request. “The Sahel G5 heads of state have expressed a desire for the continuation of France’s military engagement in the Sahel and have called for a strengthening of the international presence at their side,” the statement read. Faced with the possible withdrawal of the United States, the text expresses “its recognition” and “the desire for its continuity”

The second objective at the summit was to provide a military response to the deteriorating situation on the ground. In a report to the UN Security Council published in November, the Secretary General, António Guterres, explained that in 2019 more than 1,500 civilians had died in Mali and Burkina Faso and that more than a million people had been displaced in the countries in the region, twice as many as in 2018. Military casualties have also been considerable. 89 Nigerian soldiers were killed in an attack on a military base near the Mali border on Friday. On December 10, 71 people died in another attack on a base in the same country.

Not only will Barkhane – the name of the French operation that started in 2013 – continue in the region, but it will strengthen its military coordination with the G5 under a new name: Coalition for the Sahel. The French president announced the sending of 220 more military personnel, in addition to the 4,500 already deployed.

France, which since the beginning of operations emphasized that it covers a larger space than Europe and that has bases scattered throughout the territory, supported the idea of ​​concentrating on a smaller area. Macron announced at the press conference the creation of a joint command of France and the G-5 to fight primarily the Islamic State of Great Sahara in the border area between Mali, Burkina Faso and Niger.

A key aspect of the coalition will be the presence of a group of European special forces – not just French – dubbed Takuba. The summit was attended, in addition to the leaders of France and the G-5, Secretary General Guterres; the President of the European Council, Charles Michel; and the high representative for the EU’s common foreign and security policy, Josep Borrell.

Macron proposed the summit after the death of 13 French soldiers in late November when two helicopters collided during an anti-terrorist operation in Mali. It was the largest loss of life for the French armed forces in a war scene since Beirut in 1983. The accident was a reminder of the costs to France of a distant war, with no defined objectives or an end in sight. Some commentators compare it, saving the distances, with a French Afghanistan. Seven of the deceased belonged to the 5th combat helicopter regiment, based in Pau. Hence, this city in southwestern France was chosen as the venue for the meeting.