IT is widely viewed as one of the world's most critically-endangered trees. But now there is fresh hope the planet's rarest maple could thrive in the wild once again.
Only discovered in 1999, Acer amamiense (also known as Amami maples) is native to Amami-Oshihma, a solitary island in southern Japan, and has existed without regular monitoring or a thorough record of its natural distribution.
That was until a team of Japanese, Canadian and UK researchers carried out the first comprehensive population survey earlier this year.
And while only 12 Amami maples were found, this included three reproductively mature females and between 100-500 seedlings of different ages were seen/recorded. Previously, it was thought the island was made up of only male trees, but the female specimens offer hope for the species' future.
However, the maple’s distribution is still limited to an area less than one hectare, but there is regeneration and the trees appear to be healthy.
“While we were pleased to find that the wild status of Acer amamiense is better than we feared, the species is still very much on the edge, in more ways than one," Dan Crowley, tree conservation manager based at Westonbirt, said. "Given its perilous state, it is vital that botanic gardens collaborate where we have this special tree in our tree collections.
“The trees and Forestry England Westonbirt act as insurance and allow us to better understand how to conserve them. Our journey to the Japanese island of Amami-Oshihma was delayed due to severe weather events, a stark reminder of the threat from climate change faced by these trees – a single tsunami could wipe out the entire wild population.”
The expedition to Japan – which also included researchers from the University of British Columbia and Osaka University – was instigated by the Botanic Gardens Conservation International (BGCI) Global Conservation Consortium for Acer (maples), a group of experts from botanical gardens working together to address the conservation needs of highly-threatened maple species. The information gathered on the expedition will inform the conservation of the species in situ and updated IUCN Red List assessment.
Globally, one in five maple species (36 species) are at high risk of extinction and need conservation action. The survival of the Amami maples faces numerous threats, including urban development, agriculture and timber harvesting, compounded by the challenges posed by climate change.
Douglas Justice, associate director, University of British Columbia, added: “As we saw on Amami, maple populations are often isolated and sometimes exceptionally small. This is a particular concern in temperate mountain habitats in some developing countries, where habitat loss due to development and climate change continues to go unchecked.
"The result is that one in five maple species is now threatened with extinction. It’s worth considering that on Amami, one typhoon could potentially take out the mountainside that is home to A. amamiense. Maples are familiar trees – especially so in Canada – but because maples are common across much of the developed North, we might just take them for granted. We can’t let that familiarity make us complacent about the survival of maples in more vulnerable parts of the world.”
Forestry England Westonbirt is home to five Amami maples alongside a national collection of hundreds of different types of maple tree. The Amami maple usually flowers in May and has beautifully shaped leaves and stunning seasonal colour.
Dan added: “There are more Amami maples in gardens across the south of England than there are in the wild! Collections of endangered and threatened species in botanical gardens like Westonbirt Arboretum are a place where plants can be safeguarded.
“We’re hoping that seeds from the wild Amami maple can be sent to the UK for propagation and to secure its future we’d like to see a genetically diverse collection of Amami maples planted at places like Westonbirt Arboretum and botanic collections across the globe."
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