ERIGAVO, Somalia — In a tradition dating to Biblical times, men rise at dawn in the rugged Cal Madow mountains of Somaliland in the Horn of Africa to scale rocky outcrops in search of the prized sap of wild frankincense trees.

Bracing against high winds, Musse Ismail Hassan climbs with his feet wrapped in cloth to protect against the sticky resin. With a metal scraper, he chips off bark and the tree’s white sap bleeds into the salty air. “My father and grandfather were both doing this job,” said Hassan, who like all around here is Muslim. “We heard that it was with Jesus.”

When dried and burned, the sap produces a fragrant smoke which perfumes churches and mosques around the world. Frankincense, along with gold and myrrh, was brought by the Three Kings as gifts in the Gospel account of the birth of Jesus.

But now these last intact wild frankincense forests on Earth are under threat as prices have shot up in recent years with the global appetite for essential oils. Overharvesting has led to the trees dying off faster than they can replenish, putting the ancient resin trade at risk.

“(Frankincense) is something that is literally given by God to humanity, so if we don’t preserve it, if we don’t take care of it, if we don’t look after it, we will lose that,” said Shukri Ismail, Somaliland’s minister of environment and rural development.

The Cal Madow mountains, which rise from the Gulf of Aden in sheer cliff faces reaching over 8,000 feet, are part of Somaliland, an autonomous republic in Somalia’s northwest. The frankincense trade is Somaliland’s largest source of government revenue after livestock and livestock products, Ismail said.

Harvesting frankincense is risky. The trees can grow high on cliff edges, shallow roots gripping bare rock slithering with venomous snakes. Harvesters often slip and tumble down canyon walls.

“Every year people either break both legs or die. Those casualties are so often,” said Hassan, adding that he wished he had proper ropes and climbing gear. “It’s a very dangerous job, but we don’t have any alternative.”

Once the resin is collected, women sort the chunks by color and size. The various classes of resin are shipped to Yemen, Saudi Arabia and eventually Europe and America. Besides its use as incense, frankincense gum is distilled into oil for use in perfumes, skin lotions, medicine and chewing gum.

In the last six years, prices for raw frankincense have shot up from around $1 per kilogram to $5 to $7, said Anjanette DeCarlo, an ecologist and director of Conserve Cal Madow, an environmental group.

The rise in demand is the result of stronger marketing in the essential oils industry, which labels frankincense as the “King of Essential Oils,” DeCarlo said. The dwindling supply of high-quality resin, and competition between exporters, also are factors.

Now over-tapping is destroying the trees across the Cal Madow, as tappers try to extract as much sap as possible and make too many cuts per tree. They also tap the trees year-round rather than seasonally, preventing the trees from recovering.

“The death rate of the adult trees is alarming,” DeCarlo said. “There is potential for regeneration, but it takes about 40 years or so for these trees to become viable for tapping if it’s done right.”

Officials worry the ancient trade could disappear.

“Frankincense that the pharaohs were using came from here, so you could imagine it has a history, it has a rich history,” Ismail said. “I’m afraid that we will lose that rich history.”