Alien species overtake native plants as human activity leads to steep decline

There are now more alien species of plant in Britain than native varieties according to the Botanical Society of Britain and Ireland – with more than half of all native species declining in population.

Surveys for the BSBI’s latest Plant Atlas revealed there are 1,692 native species across England, Scotland and Wales compared to 1,753 non-native.

Many non-native plants establish themselves after spreading from gardens into the wild, or are deliberately introduced, while climate change has also enabled alien species to flourish. At the same time, changing landscapes across the nation – largely due to farming and agriculture – have resulted in lost habitats for native species, 53% of which have declined since the 1950s.

The proliferation of alien species can have significant impacts on not only other animals that rely on native species for food and shelter, but also the land on which they grow. For example, the Sitka spruce is able to grow on moorlands and peatlands, reducing their ability to store carbon, a vital element in combating climate change. The Sitka spruce has shown the biggest increase in range of all the plants recorded.

Increases in nitrogen levels due to overuse of fertilisers is one of a number of ways agriculture has led to declining numbers – the draining of damp meadows and reseeding of traditional grasslands for farming have also caused significant habitat loss.

Meanwhile, warming temperatures due to climate change have resulted in a number of species moving further north or to higher ground, such as the bee orchid. Once primarily found in the chalk grasslands of southern England, by 2003 it had reached the Scottish borders, and has now been recorded in Midlothian and Fife.

The findings are the result of the BSBI’s Plant Atlas 2020 survey, during which volunteers took part in 178,000 recording days between 2000 and 2019, submitting more than 26million records.

Dr Kevin Walker, BSBI head of science and Plant Atlas co-author, said: ‘There’s lots we can do to reverse these declines, but most important is to increase the protection plants receive, extend the habitat available to them, and to place their needs at the very heart of nature conservation.

‘We also need to ensure that our land, water and soil are managed more sustainably so that plants, and the species which rely upon them for food and shelter, can thrive.’

Craig Bennett, chief executive of The Wildlife Trusts which helped fund the project, added: ‘The decline of our beautiful native plants is heartbreaking and has consequences for us all. The loss of natural habitats due to modern farming methods over the last 70 years has been an unmitigated disaster for wildflowers and all the species that depend on them including insects, bats and birds.

‘But it’s not too late to stop this catastrophe. 

‘The Government’s new farm environment schemes must do what was originally promised and reverse the decline of nature in our agricultural landscape. Also, the promise made by the government at the recent UN biodiversity summit to halve nutrient pollution by 2030 must be honoured.’

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