Non-Native Plants Outnumber Native Plants in UK and Ireland, 20-Year Study Finds

A major 20-year-long study has revealed devastating impacts on native plants in UK and Ireland from climate change and agricultural activities. The findings show that native plants are now outnumbered by non-native species.

The study, called the Plant Atlas 2020, was conducted by the Botanical Society of Britain and Ireland (BSBI) with the help of about 8,500 volunteers, who surveyed sites across 99% of the UK and Ireland. 

In around 30 million records, the botanists recorded 3,495 flora species, with 1,692 native to Britain and 1,753 non-native species. In Ireland, botanists recorded 1,939 flora species, of which 952 were native.  

BSBI noted that 53% of native species declined in Britain, Wales and Scotland, while 56% of native flora species in Ireland declined in range, abundance or both. In Ireland, the botanists recorded 1,939 plant species, most non-native.

Plant Atlas 2020 is the third survey by BSBI and the most comprehensive. Botanists surveyed from 2000 to 2019. The results showed how species’ distributions have changed since the 1950s, with most native species and archaeophytes, or ancient introductions, declining and neophytes, or modern introductions, increasing. The Sitka Spruce, a conifer native to North America, was found to have the greatest estimated range increase as a common commercial forestry species.

“The decline of our beautiful native plants is heartbreaking and has consequences for us all,” Craig Bennett, chief executive of The Wildlife Trusts, said in a statement. “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.”

Agriculture was cited as a top driver of the decline in native species across the UK and Ireland, such as Heather, Harebell, Devil’s-bit Scabious, Agrimony, Field Gentian, Marsh Lousewort, Globeflower, Grass-of-Parnassus and Corn Marigold. Habitat loss, nitrogen fertilizers, overfertilization and reseeding have contributed to the declining native plants and increasing range and/or abundance for non-native plants.

In mountainous areas and peatlands, climate change was named as a likely cause for declines in native species, like Alpine Lady-fern, Alpine Speedwell and Snow Pearlwort, that depend on snow cover but are losing habitat in competition with non-native, warm-weather species. The spread of Sitka Spruce has also inhibited peatlands’ ability to sequester carbon.

“There’s lots we can do to reverse these declines, but the most important are to increase the protection plants receive, extend the habitat available to them, and to place their needs at the very heart of nature conservation,” Kevin Walker, BSBI head of science and co-author of Plant Atlas 2020, said in a statement. “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.”