In an analysis of a century’s worth of data on botanical gardens and arboreta, researchers reveal that global living plant collections have reached capacity, impacting their ability to meet scientific and conservation goals.
The researchers argue for a global “meta-collection” in which the estimated 3,500 botanic gardens and arboreta worldwide work more closely to conserve threatened plant species.
“Botanical gardens and seed banks are key institutions in supporting the recovery of native species,” says Veronica Briceno-Rodriguez of the Australian National Botanic Gardens (ANBG), who was not involved in the study. “They house expertise and knowledge and sometimes the only remaining genetic diversity for a species.”
The global network of living plant collections holds over 105,000 species, representing 30% of Earth’s land plant species. However, maintaining living specimens – often outside of a plant’s native environment – takes considerable human effort, resources, and data management.
Building on the wealth of data generated by living collections, the research team developed a tool that could parse 2.2 million records covering 100 years of operation for 50 representative living collections around the world.
Their analysis showed that botanical gardens are no longer increasing in size or in plant diversity, a reflection of their limited resources.
The researchers also attribute the decline in collection diversity to the Convention on Biological Diversity (CBD), which was put in place in 1993. The CBD assigned sovereignty over biodiversity to national governments to ensure sustainability and that the benefits of biodiversity resources are shared fairly. 196 nations have ratified it.
“The impact of the CBD is a remarkable demonstration of the power and value of international agreements,” says lead author Samuel Brockington, curator of the Cambridge University Botanic Garden in the UK. “But it seems to be preventing individual botanic gardens from working with many globally threatened plant species that we could help save from extinction.”
In particular, Brockington argues that the CBD makes it harder for botanical gardens to obtain wild specimens from other countries. Consistent access to wild specimens is a necessary part of maintaining a living collection because individual plants only live for 15 years on average.
“It is certainly not getting any easier to sustain the diversity of our collections,” says Brockington. “This is especially true for wild-collected plants, and they’re the most valuable for us in terms for supporting research, and in finding solutions to the twin challenges of climate change and global biodiversity loss.”
As climate change impacts the local growing conditions of botanic gardens and arboreta, Brockington calls for a “concerted, collaborative effort.”
Briceno-Rodriguez says that collaborative efforts are already underway at the ANBG, which “regularly shares living plants, cuttings and seeds with other botanical gardens and is the only botanic garden that has a publicly accessible plant database that facilitates biological material exchange with other gardens.”
Brockington adds, “[Climate change is] going to affect how well our plants survive, so we need to think rationally and collectively about the best locations to hold different species across the global network of living collections.”
Briceno-Rodriguez reports that this is being done at a local level with the ANBG sending specimens of threatened Australian species to several botanic gardens. “This allows us to gather information about the optimal growing environment for the species, propagate the species multiple times and save seeds that are often shared among seed banks for research and insurance purposes.”
Brockington and colleagues also highlight examples of individual botanic gardens succeeding to conserve threatened species. However, they say their findings imply that tackling the loss of biodiversity has not been prioritized across the world’s botanic gardens as a collective – a fact, they argue must be addressed urgently.
The research is published in the journal, Nature Ecology & Evolution.
