Almost one-fifth of bryophytes – the plant group that includes mosses, liverworts and hornworts – in Great Britain are threatened with extinction, according to a new red list assessing their conservation status.
The red list, published in the Journal of Bryology, was compiled based on criteria and categories set by the International Union for Conservation of Nature.
The study’s author, Dr Des Callaghan, a consultant specialised in bryophytes, assessed all 1,097 bryophyte species known to have occurred in England, Scotland and Wales since AD1500.
Out of the 1,029 species with sufficient information available, 191 species (19%) are threatened with extinction, he found. Among the threatened species, 59 species are critically endangered, 52 are endangered and 80 are vulnerable. None of the four hornwort species are threatened: of those on the list, 139 (73%) are mosses and 52 (27%) are liverworts.
The assessment, which was funded by Natural England, also revealed “beyond reasonable doubt” that four species had become extinct in Great Britain, “all due to the destruction of their habitat,” said Callaghan, adding that a further 20 species may also be extinct, but that further searches were needed to confirm this.
The diversity and beauty of bryophytes are “endlessly astonishing”, he said, noting that “Britain supports one of the richest bryophyte floras in Europe”. Bryophytes had been around for about 500m years and were the first plants to colonise land, he said.
“One of the main things that needs to be done to conserve our threatened species is the identification, safeguarding and management of their most important sites,” he said, adding that “this is being done, but much more effort is needed”.
Dr Rory Hodd, an independent botanist and ecologist specialising in bryophytes, said: “Red lists such as this one fulfil an essential role in identifying the species in need of conservation action, and highlighting that action is urgently needed.”
Although the findings were not surprising, Hodd said, given the “degraded state” of nature in Britain and the many threats to habitats and species there, they were “of great concern”.
after newsletter promotion
These declines reflected a wider trend of biodiversity loss across Britain and Europe, he said. A 2019 study co-authored by Hodd found that 22.5% of all European bryophyte species were threatened with extinction.
A combination of factors are driving these changes, particularly habitat loss, degradation and fragmentation, as well as air pollution and climate change, said Hodd.
“The ongoing decline in populations of many species and the special habitats on which they rely for survival is likely to accelerate in the future unless action is taken,” he cautioned.
