Trees that produce frankincense, a fragrant resin used in incense and perfumes and a central part of the Christmas story, are declining so fast that production could be halved over the next 15 years, scientists said on Wednesday.
In a study published in the British Ecological Society's Journal of Applied Ecology, ecologists from the Netherlands and Ethiopia looked at large-scale field studies and predicted that tree numbers could decline by 90 percent in the next 50 years.
If fire, grazing and insect attack, the most likely causes of decline, remain unchecked, then frankincense production could be doomed altogether, they warned.
Frankincense, best known in religious teachings as one of the gifts laid before the newborn Messiah, is obtained by tapping various species of Boswellia, a small, deciduous tree that grows across Africa from northern Nigeria to the highlands of Ethiopia and Eritrea.
Cutting the Boswellia's bark produces the frankincense resin, a white substance with a strong, sweet smell. The resin is burnt in churches, mosques and at ceremonies, as well as being used by the perfume industry and in herbal medicines.
Despite its economic importance, incense has been traded internationally for thousands of years, little is known about how tapping affects Boswellia populations.
Working in an isolated part of northwest Ethiopia near the source of the Blue Nile, a research team led by Frans Bongers of Wageningen University in the Netherlands studied 13 two-hectare plots, some where trees were tapped for frankincense and some where they were untapped.
Over two years, they monitored survival, growth and seed production of more than 6,000 Boswellia trees and used the data to build mathematical models to predict the fate of Boswellia populations in coming years. The forecasts suggest Boswellia populations are declining so dramatically that frankincense production could be halved in the next 15 years.
"Current management of Boswellia populations is clearly unsustainable," Bongers said in a statement. "Our models show that within 50 years, populations of Boswellia will be decimated, and the declining populations mean frankincense production is doomed."
The researchers found that all the Boswellia populations they studied are declining, not only those from tapped trees, a finding that suggests factors other than tapping are at the root of the problem.
Bongers said the main causes of the trees' decline are likely to be burning, grazing and attack by the long-horn beetle, which lays its eggs under the Boswellia's bark.
The scientists urged local authorities to introduce better management incentives to ensure farmers work harder to protect Boswellia trees. In the short-term this meant preventing fires and beetle attack, Bongers said, but in the longer-term, large areas should be set aside and protected for five to 10 years to allow Boswellia saplings to become established.