Frankincense, a tree resin used in perfumes and incense, faces a projected decline in tree populations due to burning, grazing and insect attacks, scientists said.

Ecologists studied more than 6,000 Boswellia trees that produce the fragrant tree resin in northwestern Ethiopia and found that the tree populations signaled a major decline in tree growth over the next 15 years, scientists said.

The Journal of Applied Ecology published the results online Tuesday.

Current management of Boswellia populations is clearly unsustainable, Frans Bongers, forest ecologist at Wageningen University, The Netherlands and study author, 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. This is a rather alarming message for the incense industry and conservation organizations.

Boswellia trees grow in Africa and the Arabian Peninsula. Their byproducts are frequently used in herbal remedies. Bongers said that extracting the resin is not the cause of decline.

Frankincense extraction is unlikely to be the main cause of population decline, which is likely to be caused by burning, grazing and attack by the long-horn beetle, which lays its eggs under the bark of the tree, Bongers said in a statement.

The declining population could also be due to the fact that older trees are not usually replaced. Wildlife and livestock may also have something to do with the decline.

The number of fires and intensity of grazing in our study area has increased over recent decades as a result of a large increase in the number of cattle, and this could be why seedlings fail to grow into saplings, Bongers said in a statement. At the same time, a large proportion of trees we studied died after being attacked by the long-horn beetle.

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