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Number of Trees in Southern Sahara Exceeds Previous Expectations

A lone camel walks in Niger's Tenere desert region of the south central Sahara on Wednesday, May 30, 2018. (AP Photo/Jerome Delay)
A lone camel walks in Niger's Tenere desert region of the south central Sahara on Wednesday, May 30, 2018. (AP Photo/Jerome Delay)
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Number of Trees in Southern Sahara Exceeds Previous Expectations

A lone camel walks in Niger's Tenere desert region of the south central Sahara on Wednesday, May 30, 2018. (AP Photo/Jerome Delay)
A lone camel walks in Niger's Tenere desert region of the south central Sahara on Wednesday, May 30, 2018. (AP Photo/Jerome Delay)

The southern Sahara and the Sahel are home to more trees than thought, which have a "crucial role" in biodiversity and people's lives. An international research team has developed an artificial intelligence (AI) pattern recognition program to count trees with a plant surface of more than 3 square meters, from over 11,000 high definition satellite images, AFP reported.

Over an area of 1.3 million square kilometers in the south of the Sahara, the Sahelian strip, and sub-humid zones in West Africa, they were able to count more than 1.8 billion trees, the researchers wrote in the journal Nature.

Based on the findings, the average tree number is 13.4 per hectare, with a median plant cover of 12 square meters. The researchers noticed that this vegetation, certainly sparse, "plays a crucial role for biodiversity and for the ecosystem as carbon storage, food resources, and shelter for human and animal populations."

"Although the total vegetation cover is low, the relatively high density of isolated trees calls into question the prevalent idea of desertification of drylands, as even the desert could offer a surprising density of trees," they added. The density increases as it descends towards the wetter areas in the south, from 0.7 trees per hectare in the "hyperarid" areas to 9.9 in arid zone, 30.1 in semi-arid zone, and 47 trees per hectare in subhumid zone. In addition to this count, the study offers a new method to study the presence of trees outside dense forest areas, and in particular their role in climate change mitigation and potentially poverty, through their contribution to agricultural systems.

"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 vegetation are effective", one of the researchers, Jesse Meyer from the NASA explained in a statement.

"The used artificial intelligence technique also suggests that it will soon be possible, within certain limits, to map the location and size of all trees. This information is fundamental to our understanding of ecology on a global scale," estimated Niall P. Hanan and Julius Anchang of the University of New Mexico, in an analysis of the study.

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Engineers Seek to Save 150-year-old Lighthouse from Crumbling into Hudson River

The lighthouse was built in the river 100 miles (161 kilometers) north of Manhattan to keep boats from running aground on mud flats. AP
The lighthouse was built in the river 100 miles (161 kilometers) north of Manhattan to keep boats from running aground on mud flats. AP
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Engineers Seek to Save 150-year-old Lighthouse from Crumbling into Hudson River

The lighthouse was built in the river 100 miles (161 kilometers) north of Manhattan to keep boats from running aground on mud flats. AP
The lighthouse was built in the river 100 miles (161 kilometers) north of Manhattan to keep boats from running aground on mud flats. AP

Federal engineers will begin the process of preserving a functioning 150-year-old lighthouse that sits precariously on a mudflat in the middle of the Hudson River in New York, officials announced this week.
US Sen. Chuck Schumer and the Army Corps of Engineers said that $50,000 has been allocated to study how to protect the Hudson-Athens Lighthouse, which began operating in 1874 and was this year placed on the National Trust for Historic Preservation's list of the country’s 11 most endangered historic places.
Schumer, a New York Democrat, said he believes the development is the next step to securing all the money needed to save the structure, which is only years away from starting to crumble into the river due to ongoing erosion, according to preliminary studies by a historic preservation group.
“This is a landmark, it’s sort of like the Statue of Liberty in a certain sense, of the Hudson River,” Schumer told The Associated Press by phone after announcing the new funding at a riverfront park in Athens, New York, which has a view of the lighthouse. “When people see the lighthouse and learn its history, they learn the history of the country."
The Corps of Engineers will now meet with the Hudson-Athens Lighthouse Preservation Society, which owns the building and maintains it as a museum, and agree on a plan to fix the property, Schumer said.
He said the millions of dollars needed to ultimately rebuild the small island and preserve it are “virtually certain” because it has been listed as a top priority for preservation.
The lighthouse was built in the river 100 miles (161 kilometers) north of Manhattan to keep boats from running aground on mud flats between Athens, on the west side of the Hudson River, and the city of Hudson, on the east side. The lighthouse is still in use, though now with an automated LED beacon.
It sits on roughly 200 wood pilings packed in mud beneath the water. Turbulence from passing commercial ships is washing away that mud and exposing the pilings to river water, accelerating decay.
The society has proposed expanding the foundation the lighthouse is built on so that events can be held there and more visitors can walk on the island at once. It has been raising money to build a ring of corrugated steel designed to shield the structure from river turbulence.