Tropical botanical gardens: both a fantasy and a necessity

My dream of lounging in a hammock surrounded by the flora of the Brazilian rain forest in a luscious botanical garden is now supported by biodiversity experts. A seminal study on ex situ conservation was recently published in Nature. It found that 30% of all plant species biodiversity is present in botanic gardens including 41% of threatened plant species, a total of 105,634 species. While the numbers are certainly promising, much of the remaining work to be done lies in the tropics.

Biodivvy_Botanical Gardens


The study pinpoints ways to enhance the effectiveness of the global network of botanic gardens for ex-situ conservation, specifically with reference to Target 8 of the Global Strategy for Plant Conservation (GSPC) 2011-2020 of the UN Convention on Biological Diversity. It states: “At least 75 per cent of threatened plant species in ex situ collections, preferably in the country of origin, and at least 20 per cent available for recovery and restoration programs.” The study reveals that for the global network of ex situ conservationists to reach their target, the glass is more than half full. Moreover, much of the remaining work to be done lies in the tropics.

It is often difficult to fathom both the extent of plant biodiversity degradation and our simultaneous dependence on such diversity to ensure the proliferation of our medicinal, agricultural, physical, and planetary health. Given that 20% of plant diversity is threatened with extinction, such a broad-ranging study provides the necessary impetus to take further action. Botanical Gardens Conservation International (BGCI), which has a vast global network of Botanical Garden affiliates, works to reach the targets outlined by GSPC through its mission and strategy and it partnered to produce the recent study.

The study’s findings raise an important concern about the global distribution of botanic gardens. Those in the temperate climates of the northern hemisphere largely outweigh those in the south. The study states that 91% of recorded accessions, and 93% of recorded species are documented from ex situ collections in the Northern Hemisphere. This is to be expected, considering the global distribution of wealth. However, according to the study, the greater abundance in northern climes, “runs counter to natural latitudinal gradients, where tropical ecosystems harbor the bulk of plant species diversity.” Tropical species account for 76% of the missing 70% of species not yet managed in ex situ botanic gardens.


Global distribution of ex situ plant collections and the availability of data for the contents of these ex situ collections. (a) the relative species diversity present in each of the 1,116 BGCI member institutions that share plant record data with BGCI (b). The diameter of each bubble is scaled to the number of species recorded at the institution (data from BGCI GardenSearch and BGCI PlantSearch).


The study also calls for more attention to be placed on filling the gap in protection for threatened species: “It remains essential that biogeographic gaps in digital collection data are filled, to provide the robust cyber-infrastructure needed for coordinated ex situ plant conservation.” Digital data collection for botanical gardens in regions with less funding remains a stumbling block to achieving the desired protection coverage. Documentation ultimately leads to more effective preservation, which is why it is the first objective of the GSPC to ensure that “Plant diversity is well understood, documented, and recognized.”

Currently, BCGI is the largest data collecting organization with 1,116 member organizations uploading information into its database called PlantSearch. According to the study, this list is the most comprehensive list of botanic garden accession names, containing over 1.3 million records. For the purposes of conservation, the entry of a plant species into the database gives the much needed recognition for determining gaps in species protection coverage.

Ex-situ plant conservation often presents a seemingly more cost-effective alternative to in-situ preservation, a debate I’ve detailed in an earlier blog post. While ex-situ conservation does not provide the same rigor of preservation that in-situ can provide, both are essential to reaching a sustainable level of biodiversity preservation for future generations. Ex-situ preservation often has the added benefit of having a viable infrastructural network for data collection and monitoring.

With the help of this study, greater priorities are placed on expanding species protection in botanical gardens in the southern hemisphere, expanding the capacity of new and existing facilities to effectively record their species, and the need to fill in gaps in the number and types of threatened species protected in botanic gardens.

Click here to support the efforts of BCGI

Please post photos of your local botanical garden in the comments!

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