Pasqueflower in a Nature reserve in Shillington, England. (Dr Kevlin Walker, BSBI website)

Almost half of Britain's native plant species have decreased in the last two decades and were outnumbered currently by non-native strains, a Botanical Society of Britain and Ireland (BSBI) study concluded.

The change has impacted native insects and other animal species that have evolved depending on the local plant species.

In a report published in Plant Atlas 2020, thousands of experts from the BSBI - upon almost two years of research - warned that the climate crisis, in addition to wrong farming practices, were the main contributors to the native plant species' decline, calling for immediate action to prevent further deterioration of the situation.

Changes introduced to agricultural practices since the 1950s, which include nitrogen enrichment, destruction of natural habitat, and increased stock feeding, resulted in the decline of several types of plants, such as heather and harebell, and the draining of damp meadows, which, in turn, led to a significant decline in other species, such as devil’s-bit scabious, a plant that a rare breed of butterflies rely on for food.

Corn marigold wildflowers, for example, recorded a steep decline compared to other species at 62%, as arable lands have dropped or were over-fertilized.

Chief of The Wildlife Trusts, Craig Bennett, said the impact of the decline of native plant species will affect everyone, stressing that new farming methods contributed to the environmental disaster.

“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," he said.

However, Bennett considered that the damage can still be stopped with appropriate public action.

“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, protection for local wildlife sites needs to be increased, and the promise made by the government at the recent UN biodiversity summit to halve nutrient pollution by 2030 must be honoured.”

The researchers, after studying 3,445 plant species, found that 1,692 were native to the country while the other 1,753 were non-native.

The alien plant strains were, according to the research, intentionally or mistakenly introduced by humans to the ecosystem. A large number of the species originate from gardens and later expanded into the wild as big populations.

Peatland habitats have been severely impacted by the introduction of non-native spruce, while sitka spruce has recorded the most significant increase in the wild among the other species.

Dr. Kevin Walker, BSBI's Head of Science and the research paper's co-author, said, "There’s a lot 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. 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.”