They planted a forest at the edge of the desert. From there it got complicated.
Josie Glausiusz/ National Geographic:
A delicate breeze drifts through the sun-dappled understory of these spare, out-of-place woods, softening the heat of late July. Beneath the spindly Aleppo pines, spiny shrubs nestle among limestone boulders. The only sounds are the buzzing of insects and the occasional roar of a military jet.
In spring, though, following the winter rains, this place bursts with new life. Pink and yellow wildflowers carpet the forest floor; camels and horses graze in open meadows. Gazelles, hyenas, foxes, rabbits, fieldmice, lizards, and snakes all dwell in Yatir—a human-made oasis on the northwest edge of the Negev Desert, around 30 miles south of Jerusalem.
Planted in the 1960s by the Jewish National Fund (JNF), a non-profit land development agency that manages more than a tenth of the country, Yatir is Israel’s largest planted forest. Had these hillls been left alone, they might be covered in low shrubs like Jerusalem sage and hairy bread-grass. Instead, four million trees, 90 percent of them hardy Aleppo pine, spread over almost 12 square miles of semi-arid land.
The trees are neither irrigated nor fertilized, and yet somehow the forest has survived for almost 60 years. “Yatir Forest proves that we can combat desertification, and heal the wounded earth,” the JNF website says. At a time when people around the world are looking to tree-planting and forest expansion as a way to soak up carbon dioxide and combat climate change, Yatir is an inspiring example. But can it last, and was it really a good idea?
Planting trees on semi-arid shrubland is misguided, some Israeli environmentalists argue, because it endangers birds, lizards, and small mammals that have evolved in tandem with native shrubs and grasses— and it doesn’t do much for climate anytime soon.
What’s more, the forest’s ability to survive in a warming world is uncertain. Between 5 to 10 percent of Yatir’s trees—up to 80 percent in some areas—have withered and died in the past decade, as a series of extreme droughts have struck the region. Meanwhile, the forest is not regenerating: Drought and grazing by sheep and goats are killing the pine seedlings.
“Trees here are pushed to the edge,” says Eyal Rotenberg of the Weizmann Institute of Science, who has studied Yatir for more than two decades. He and his colleagues think the forest can and should survive. But if so it’s going to have to change.
Carbon isn’t everything
After lunch under the pines at the institute’s long-term research site at Yatir, Rotenberg brushes away harvester ants grappling with leftover rice grains, then explains how Weizmann ecophysiologist Dan Yakir, the leader of the project, set up the research station in 1998. Yatir receives around 11 inches of rain per year, on average, mostly from December to March. The forest’s resilience in such a dry climate was a puzzle, as was its impact on its surroundings.
“For us, Yatir is a laboratory where we study the forest’s effect on climate, at the edge of the conditions for forest growth,” says Rotenberg, who joined the project in 2000. “What we learn now about Yatir will be serving a warmer, dryer world in many regions.”
In principle, expanding forest cover in similar places like the semi-arid Sahel, where the ambitious Great Green Wall project has made halting progress since it was launched in 2007 by the African Union, could slow global climate change, as well as desertification.
Fifteen years’ worth of measurements in Yatir, beginning in 2001, do show that the forest takes up a surprising amount of carbon—as much as forests in more humid areas, says Rafat Qubaja, a Palestinian researcher, now at Arizona State University in Tempe, who did his PhD at Weizmann. Semi-arid shrub and grasslands cover nearly a fifth of the planet’s land, some 10 million square miles; if they all were planted with trees, the Yatir results suggest, they might absorb around 10 percent of current fossil fuel emissions.
But the extent to which they would cool the planet is less clear. On satellite pictures the Yatir Forest forms a huge dark blob in the bright-colored, shrubby desert, which means it absorbs more solar radiation. As Rotenberg and Yakir showed in a 2010 Science paper, the darker Yatir Forest absorbs more energy, converts it into heat, and releases it back to the atmosphere. Initially the heat released by Yatir outweighs the cooling effect of its carbon dioxide absorption. Rotenberg estimates it willl take more than 200 years for the forest to have a net cooling effect—if it survives that long.
Of course, forests have other benefits besides their ability to absorb carbon. Qubaja, who was born in the West Bank town of Tarqumiyah, came to relish the tranquillity of Yatir. “Many times I am sitting below the trees and enjoying it, the quiet, the personal peace,” he says.
Trees aren’t necessarily natural
Though Aleppo pines are mentioned in the Bible, pollen surveys and archaeological studies suggest the species was rare in the region until the 20th century. First planted extensively in Palestine in the 1920s by the British Mandate Forestry Service, they constituted about 50 percent of the forests planted by the JNF by the 1980s. They grow rapidly and on any kind of soil. They can be seen now all over Israel, from the northern Galilee mountains to the northern Negev.
Not everyone in the country is happy about that. The Society for the Protection of Nature in Israel (SPNI), for example, adamantly opposes further planting of trees in naturally unforested open spaces such as grasslands and shrublands. In a 2019 report, the SPNI claims that afforestation in sensitive ecosystems has a destructive impact on Israel’s unique biodiversity. “I love trees,” says Alon Rothschild, head of biodiversity policy at the SPNI, “but you don’t have to stick them in every place.”
Planting trees in cities or villages, where they offer shade and cooling moisture, or in abandoned quarries and farmland, is a great idea, he says. Natural forests in the northern Carmel range and elsewhere should be preserved. “But the majority of the area in Israel is not naturally forest,” Rothschild says, and those shrubby landscapes should be preserved too.