Frankincense in peril

Abstract

The harvest of plant parts and exudates from wild populations contributes to the income, food security and livelihoods of many millions of people worldwide. Frankincense, an aromatic resin sourced from natural populations of Boswellia trees and shrubs, has been cherished by world societies for centuries. Boswellia populations are threatened by over-exploitation and ecosystem degradation, jeopardizing future resin production. Here, we reveal evidence of population collapse of B. papyrifera—now the main source of frankincense—throughout its geographic range. Using inventories of 23 populations consisting of 21,786 trees, growth-ring data from 202 trees and demographic models on the basis of 7,246 trees, we find that over 75% of studied populations lack small trees, natural regeneration has been absent for decades, and projected frankincense production will be halved in 20 yr. These changes are caused by increased human population pressure on Boswellia woodlands through cattle grazing, frequent burns and reckless tapping. A literature review showed that other Boswellia species experience similar threats. Populations can be restored by establishing cattle exclosures and fire-breaks, and by planting trees and tapping trees more carefully. Concerted conservation and restoration efforts are urgently needed to secure the long-term availability of this iconic product.

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Fig. 1: Distribution of major frankincense-producing species and main threats to existing populations.
Fig. 2: Distribution and size structures of Boswellia papyrifera populations.
Fig. 3: Regeneration failure in Boswellia populations obtained from tree-ring analysis.
Fig. 4: Projected development of Boswellia populations and frankincense yield at 23 sites.

Data availability

The data reported in this paper are tabulated in the Supplementary Data and can be accessed in the Github repository (https://github.com/groenendijk/Frankincense-demography).

Code availability

The R script used for the IPM analysis can be accessed in the Github repository (https://github.com/groenendijk/Frankincense-demography).

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Acknowledgements

This work is part of the FRAME integrated programme (‘Frankincense, myrrh and arabic gum: sustainable use of dry woodland resources in Ethiopia’). A large part of this programme was financially supported by Netherlands Organisation for Scientific Research-Science for Global Development (NWO-WOTRO, grant no. W01.65.220.00). Additional support was received from: a SIDA grant to M.Tol., BES grants 2732/3420 to M.Tol. and 1415/1782 to E.B., Wageningen University Sandwich grants to E.B., M.Tol. and W.O., IFS grant C/4775-1 to M.Tol., NUFFIC grant CF6676/2010 to E.B. and Marie Curie Actions Programme grant PITN-2013-GA607545 to P.G. P.G. was also supported by FAPESP grant 18/01847-0.

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F.B., F.J.S., P.A.Z. and P.G. conceived the study. F.B. and P.G. compiled the data. P.G. and P.A.Z. performed the demographic modelling. M.D. evaluated forest change. F.B., P.A.Z., F.J.S. and P.G. wrote the paper. All authors contributed data and commented on the manuscript.

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Correspondence to Frans Bongers.

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Supplementary Figs. 1–8, Supplementary Tables 1–5, Supplementary method 1, Supplementary Note 1, Supplementary References 1–12

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Bongers, F., Groenendijk, P., Bekele, T. et al. Frankincense in peril. Nat Sustain 2, 602–610 (2019). https://doi.org/10.1038/s41893-019-0322-2

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