A novel, low-tech idea is helping Tanzania’s lion population rebound: So-called “living fences” — which enclose livestock and are constructed of actively growing trees and chain-link fencing — have cut lionattacks and retaliatory killings by more than 85 percent in the areas they’ve been installed, the Guardian reports . Traditionally, the Masai have built livestock enclosures out of thorny acacia trees, but those fences are relatively fragile. Chain-link fencing alone is more durable, but leopards and small lions can scale the fences, and hyenas can tunnel in below. By interweaving actively growing African myrrh trees with the chain link fencing, the Masai have created a barrier that lions can’t climb over, and their root systems prevent predators from digging under the fence. Because livestock predation has been cut, communities that had been killing six or seven lions annually now kill, on average, less than one, leading to a rebound in lion populations.