Botanic Gardens Conservation International
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New report highlights that only one in four of the most threatened trees are represented in ex situ collections

22 October 2015

The Global Trees Campaign aims to avoid all tree extinctions in the wild. An important component of conservation action must be ex situ conservation: securing a species outside of its natural range, as a back-up measure in case remaining wild populations are lost. Our new report, released today, highlights that 74% of the most threatened trees are absent from ex situ collections, lacking this vital conservation action that could save them from extinction.

These results are based on research work undertaken by BGCI. Our first step was to develop a list of threatened trees against which to measure progress. Doing this was no small task.

First, we collated Critically Endangered (CR) and Endangered (EN) assessments of known trees, for example from the IUCN Red List and BGCI tree red lists.

We also collated CR and EN assessments of plants, without recorded life form, for example from national plant red lists.

In addition, we developed a list of trees, with input from national tree lists and monographs, so relevant assessments could be extracted from the list of CR and EN plants. Our tree list also had a final manual check by the Global Tree Specialist Group and other experts.

This resulted in a list of CR and EN trees, to compare ex situ collection records against.

Alongside efforts to develop the list of threatened trees, botanic gardens, arboreta and associated seed banks were encouraged to upload their latest collection information to BGCI’s PlantSearch database: an online global portal of living plant collection lists.

So what do the results tell us?

  • 5,330 trees with conservation assessments are considered CR or EN globally

Our compiled list of threatened trees identified 3,000 additional assessments to those on the IUCN Red List, as a result of incorporating additional data sources. This represents the best list of threatened trees available and the best estimate to date of the number of trees known to be threatened.


  • Only one in four threatened trees are reported as held in ex situ collections

This means that the majority of threatened trees are not backed up in collections and are at great risk of extinction from stochastic events even if in situ protection measures are in place, or from extraction or habitat loss if in situ protection measures are inadequate.

To download the full report, containing guidance on which species to prioritise for collection and how to ensure collections are of greatest conservation value, click here.




  • In addition, our work has collated a list of c. 65,000 accepted names of tree species, making it the most comprehensive global tree list developed to date.

This baseline study, and the tree lists developed, enable GTC and our partners to identify and prioritise trees in greatest need of conservation and to take action. With over 500 botanic garden members worldwide, BGCI will use the results to mobilize our partners to ensure all threatened trees within their region are protected in secure and genetically diverse conservation collections.

In 2016, our tree list, GlobalTreeSearch will be completed and geo-referenced.

By 2020, the GTSG will ensure conservation assessments have been carried out for all of the world’s tree species.

Our expanding portfolio of conservation projects and resources provides guidance on appropriate conservation action.

By providing information and training, mobilizing action and raising funds, GTC and our network of partners adopt a zero extinction strategy for the world’s trees.


Join us in our efforts!

To provide tree names for GlobalTreeSearch, please contact

To notify us of existing tree red list assessments or red listing efforts, please contact:

Upload your collection records to BGCI’s PlantSearch database to ensure the conservation work of your institution is counted in future assessments:

If you are keen to support our conservation work for threatened trees, please consider making a donation, or get in touch:

To download the full report click here.


Home page photo credit: Xander van der Burgt/RBG Kew

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