They planted a forest at the edge of the desert. From there it got complicated.
Trying to judge the success or failure of Yatir, Israel's largest human-made forest, depends on the way you define success. And the person you’re asking.
Yatir Forest, Israel — 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.
Planting forests in such places excludes native species that are adapted to shrubland, he says, including endangered ground-nesting birds like the spectacled warbler, or raptors such as the lesser kestrel and long-legged buzzard, which need open landscapes to dive on prey. The heavy machinery and herbicide used in tree-planting can also damage fragile dryland soils, crushing the thin crust. It consists of minute plants, lichens, and fungi that provide food for insects, reptiles, and birds.
There is also a human cost to the JNF's vision of making the desert bloom. In 2015, Israel's Supreme Court authorized the eviction of 1,000 Arab Bedouin residents of two Negev villages, Atir and Umm al-Hiran, in order to build the new town of Hiran—and also, according to Adalah, the Legal Center for Arab Minority Rights in Israel, to expand the Yatir Forest.
Since Israel’s founding in 1948, says Adalah lawyer Myssana Morany, forest projects have often served as a pretext to confiscate Palestinian land. The ruins of Palestinian villages lie under many Israeli forests or parks.
By continuing afforestation in the Negev, "the State is claiming that they know best what the right connection should be between the community and nature," says Morany. Bedouin communities grazing their flocks, she says, "know more than anyone how to be in coexistence with nature.” The real danger to it comes from building new cities and roads in the area, not from “the Bedouin community who are taking their goats around the forest."
What is natural, anyway?
Figuring out what “nature” even means in this ancient land, heavily exploited by humans for millennia, isn’t easy. When Jewish immigrants settled in Palestine more than a century ago, the land "was under amazing high levels of grazing and it was undergoing abnormal desertification," says plant biologist Tamir Klein, who directs the Weizmann Institute Tree Lab. Domestic animals like goats and sheep "are the murderers of plants,” he says. “They suck everything, and they leave no place untouched. They just eat all the herbs and all the seedlings."
Klein agrees with Rothschild in part: “We should not plant trees everywhere. There should be room for native shrublands and for grasslands, and we have them in Israel." But he supports some of the JNF’s afforestation efforts, including Yatir—which he says is in trouble.
Aleppo pines are hardy but also short-lived; their average lifespan is 80 years. Twenty to 30 years from now, the original pines will be dead or dying, and there is very little regeneration of the forest, Klein says. That’s in part because of grazing, but primarily because drought is killing nearly all the pine seedlings.
Yatir "has been successful ever since it was planted in the 1960s," Klein says. "But it seems that it won't be as successful in years to come, because of climate change."
Yet Israel does have "an amazing diversity of plants," Klein says, including 70 native species of trees such as olive and oak. So when the JNF asked him to help design the future of Yatir Forest, Klein suggested that it should consider planting other trees: Salt-tolerant tamarisk, Ziziphus spina-christi (Christ's Thorn Jujube), and especially acacia.
Acacia trees, says Klein, can tolerate three extremes: aridity, high solar radiation, and high temperatures. In a recent study, his team found that acacia trees in Israel's dry Arava valley (which receives less than three inches of rain per year) actually grow fastest during the dry summer months, when maximum daily temperatures can reach as high as 113°F. One of their secrets seems to be exceedingly long roots, which can extend more than 30 feet down to underground aquifers, and 25 feet horizontally.
"Under future drying and warming scenarios," Klein and his co-authors note, sparse woodlands consisting of deep-rooted acacia "might survive climate change better than dense forests."
Rotenberg is also optimistic that Yatir will persist in some form. On the journey from the Weizmann Institute in Rehovot south to Yatir, passing through the hills overlooking the Valley of Elah—“the valley of the terebinth,” where David is said to have fought Goliath—he points out terebinth trees but also Judas trees, oaks, and two kinds of cypress. In the absence of grazing by goats or sheep, he insists, trees regenerate naturally even in semi-arid regions. "If you look at every place that is abandoned, the forest will take over," he says.
At Yatir, he says, "we are all the time surprised by the ability of trees to survive." Even during an extreme drought from 2008 to 2009, when the forest endured 349 straight days without rain, most trees persevered.
"I'm sure that if no one touches the forest in 100 years, when you come to visit here, you'll see some pine trees standing," Rotenberg says. "The forest won't give up very easily."
