Around half a million giant sequoia and closely related coastal redwoods are growing in the UK, compared to just 80,000 still growing in California's Sierra Nevada mountains.

The enormous trees, which can grow up to around 300 feet (90 metres) tall over their 3,000-year lives, grow at similar rates in the UK to those in their native California range, despite the ecological and climactic differences between the two environments, scientists have found, and can also capture large amounts of carbon.

Researchers "weighed" study specimens using 3D terrestrial laser scanning to make detailed structural measurements of the trees to capture their above-ground biomass.

Calculating their growth rate was made simpler by the fact that many of the specimens' ages are known, as the trees were first imported to the UK as seeds and seedlings in 1853.

Seen as a symbol of wealth to Victorians, they were often planted at the entrance to large houses and estates, and in avenues, churchyards and parks.

Noting "recent interest in planting more redwoods" due to "their public appeal and potential for storing carbon", researchers from University College London (UCL) and the Royal Botanic Gardens, Kew, set out to find out how well they grow in the UK for the first time - taking into account the milder climate and wider range of rainfall.

The team put together the first dedicated map of giant sequoias in the UK, showing the location of nearly 5,000 known trees.

They focused on 97 individual trees at three sites - an avenue at Benmore Botanical Garden in Dunoon, Scotland, Kew's Wakehurst Place in West Sussex, and a path in mixed woodland in Havering Country Park, Essex.

UK-grown giant redwoods can capture around 85kg of carbon a year, depending on climate, management and age, the study found.

The tallest tree the researchers found measured about 180 feet (54.87 metres), smaller than their US counterparts, in part due to the UK specimens' youth.

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The study's lead author, Ross Holland, formerly at UCL and now at East Point Geo, said: "Giant sequoias are some of the most massive organisms on Earth and in their native range make up some of the most carbon dense forests in the world due to their great age.

"We found that UK redwoods are well adapted to the UK and able to capture a large amount of carbon dioxide."

The research was published in the journal Royal Society Open Science.