Frankincense has been traded on the Arabian Peninsula and in North Africa for more than 5000 years. Frankincense is tapped from the very scraggy but hardy Boswellia tree by slashing the bark, which is called striping, and allowing the exuded resins to bleed out and harden. These hardened resins are called tears. Current rates of tapping frankincense - which according to the Bible was given to the baby Jesus by the three wise men at Christmas and which will feature in thousands of Nativity plays in coming days - are endangering the fragrant resin's sustained production, ecologists have warned. Writing in the December issue of Journal of Applied Ecology, ecologists from the Netherlands and Eritrea say that over tapping the trees results in them producing fewer, less viable seeds.
For thousands of years, frankincense has been hugely important both socially and economically as an ingredient in incense and perfumes. But, say the ecologists, its production in the Horn of Africa is declining because Boswellia woodlands are failing to regenerate.
Frankincense is used in perfumery and aromatherapy. Frankincense is extensively used in many Christian Churches including the Eastern Orthodox, Oriental Orthodox, and Catholic Churches.
Boswellia Sacra trees are considered unusual for their ability to grow in environments so unforgiving that they sometimes grow directly out of solid rock.
The trees start producing resin when they are about 8 to 10 years old. Tapping is done 2 to 3 times a year with the final taps producing the best tears due to their higher aromatic terpene, sesquiterpene and diterpene content. Generally speaking, the more opaque resins are the best quality. Although fine resin is also produced more extensively in Yemen and along the northern coast of Somalia.
Recent studies have indicated that frankincense tree populations are declining, partly due to over-exploitation. Heavily tapped trees have been found to produce seeds that germinate at only 16% while seeds of trees that had not been tapped germinate at more than 80%. In addition, burning, grazing, and attacks by the longhorn beetle have reduced the tree population.
The ecologists in the new study hypothesized that poor regeneration was due to the fact that intensive tapping meant that the trees were diverting too much carbohydrate into resin, at the expense of reproductive organs, such as flowers, fruit and seeds. Working in south-western Eritrea, they tested the hypothesis by looking at how many seeds intensively tapped trees produced, and their germination rates, compared with untapped trees.
According to one of the authors of the study, Professor Frans Bongers of Wageningen University: "This study strongly suggests that there is competition between investment of carbohydrates in sexual reproductive structures and synthesis of frankincense in Boswellia papyrifera. At all study sites, trees subject to experimental tapping produced fewer flowers, fruits and seeds than trees that were exempt from tapping. Furthermore, tapped trees produced smaller fruits with seeds of lower weight and reduced vitality than non-tapped trees."
Based on their findings the authors say that, for production to be sustainable, the way that frankincense is tapped needs to be changed. "In order to control the decline in fruit and seed production, less intensive tapping procedures should be developed. As our results show that six tapping points per tree are already having a negative impact, we suggest reducing the number of tapping points. New tapping regimes should include rest periods when there is no resin harvesting to allow the trees to recover," they say.
Although the impact of tapping trees for other crops, such as latex and pine resin, has been studied in plantations, this is the first study to show quantitatively the fragile relationship between the extraction of wood exudates and tree regeneration in natural populations.
For further information see Abstract or Frankincense.
Frankincense Pellets image via Wikipedia.