Quantifying Endangerment Value: a Promising Tool to Support Curation Decisions

Botanic garden collections are increasingly seeking to quantify and improve the value of their collections for science, horticulture, conservation and other uses. Quantifying the value of a collection depends on the mission of the institution. Many botanic gardens are prioritising the conservation of rare and threatened species towards preventing plant extinctions. In doing so, botanic gardens must make decisions about which plants should remain, be replaced or be added to their collections, and how to allocate staff and resources to care for individual plants, while considering funding and space limits. So, how can curators make the biggest impact towards conserving plant species? We present a promising method to quantitatively assess which plant species might be higher or lower conservation priority to an ex situ collection, using what we term ‘endangerment value’ – the value of collections for preventing plant extinction. We apply this method to four genera of high importance at The Morton Arboretum and showcase advantages of this approach as well as pitfalls. We found this method useful for priority setting, but note that the inclusion and exclusion of different data and how they are weighted impacts the ranking of priority species – an important lesson for any prioritisation method. We hope this method will inspire and help other botanic gardens to evaluate their current and future endangerment value and set priorities for maintaining and growing ex situ collections globally.