Ex situ conservation of plant diversity in the world’s botanic gardens


Botanic gardens conserve plant diversity ex situ and can prevent extinction through integrated conservation action. Here we quantify how that diversity is conserved in ex situ collections across the world’s botanic gardens. We reveal that botanic gardens manage at least 105,634 species, equating to 30% of all plant species diversity, and conserve over 41% of known threatened species. However, we also reveal that botanic gardens are disproportionately temperate, with 93% of species held in the Northern Hemisphere. Consequently, an estimated 76% of species absent from living collections are tropical in origin. Furthermore, phylogenetic bias ensures that over 50% of vascular genera, but barely 5% of non-vascular genera, are conserved ex situ. While botanic gardens are discernibly responding to the threat of species extinction, just 10% of network capacity is devoted to threatened species. We conclude that botanic gardens play a fundamental role in plant conservation, but identify actions to enhance future conservation of biodiversity.

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Fig. 1: Global distribution of ex situ plant collections and the availability of data for the contents of these ex situ collections.
Fig. 2: Percentage of plant diversity held ex situ at different taxonomic hierarchies.
Fig. 3: The distribution of ex situ collections and collection data relative to the natural distribution of plant diversity.
Fig. 4
Fig. 5: Threatened land plant species in botanic collections.
Fig. 6: Presence and absence of IUCN Red List threatened plants in ex situ collections.


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We thank N. Walker-Hale and M. Castle for statistical help, R. Smith-Unna for help with programming, M. Jones for help with BGCI databases, M. Rivers for access to an early release version of the BGCI ThreatSearch data, and M. Bohm for compiling initial national conservation assessments that went into BGCI ThreatSearch. We thank the Brockington Laboratory, N. Cunniffe, J. Walker, S. Smith,  S. Sharrock and BGCI staff for useful discussion. We acknowledge the Cambridge University Botanic Garden and the National Environmental Research Council for financial support to S.B.

Author information

S.B. and P.S. conceived the study, P.S. released the data, R.M. cleaned the data, S.B. designed the analyses, R.M. and S.B. performed the analyses, and S.B. and P.S. wrote the manuscript.

Correspondence to Samuel Brockington.

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Life Sciences Reporting Summary

Supplementary Table 1


Supplementary Table 2


Supplementary Table 3

Notes on life habit, species paucity, endemism, biogoegraphic distribution.

Supplementary Table 4

Evolutionary distinctiveness (FairProportion, MYA).

Supplementary Table 5

Missing/total clade genera.

Supplementary Table 6

Number of accepted species.

Supplementary Table 7


Supplementary Table 8

Species ID.

Supplementary Table 9

Genus Species Sourcefile.ID Latitude.Record.Count Max

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