Highways England has launched a new biodiversity policy which will see it creating the types of soils on its verges and raodsides that will encourage the growth of more wildflowers.
More fertile areas with lots of topsoil – rich in potassium, phosphorus and nitrogen – favour aggressive grasses, dock and nettle, which are all fast-growing plants that can out-compete delicate wildflowers for water, nutrients, space and light, according to the organisation.
On all major schemes, contractors are now being instructed to follow a new Low Nutrient Grasslands policy aimed at keeping away the ‘bullying’ plant species which love high nutrient soil, and allowing wildflowers to thrive, creating vital habitat for insects and other wildlife.
Highways England Environmental Advisor Ben Hewlett said: “Our new policy means we’ll create more biodiverse new grasslands as standard. And as 97% of all species rich grasslands have been lost in the last century, it is great to think that our construction design standards could create substantial areas of biodiverse grasslands, stretching throughout England.
“This is another great example of how we are moving away from simply minimising the impact of our work on the environmental impacts towards actually improving the environment through our work.
“The increase in wildflowers and wider biodiversity should also provide some impressive visual displays, and help to connect people with nature and improve the wellbeing of millions of people using our roads every day.”
Wildflowers thrive on low nutrient soil and the new policy is focused around the management of topsoil – or rather removing it from new grassland areas to lowers the nutrient level, creating the perfect conditions for the flowers.
Removing soil nutrients slows growth rates of vegetation, reducing mowing and management requirements, while improving biodiversity by allowing wildflowers to germinate and thrive without competition from more vigorous plants.
The new initiative will see all grassland areas on improvement schemes finished with subsoil or bare substrate such as chalk. These will then be allowed to regenerate naturally or be seeded with wildflowers and grasses appropriate to the substrate type to create open grasslands high in biodiversity, which in turn support pollinators and other wildlife, while providing road users with a more aesthetic landscape.
By adopting this new policy, Highways England is hoping to: improve safety by reducing the number of maintenance visits, reduce the carbon footprint through fewer maintenance visits, maximise grassland biodiversity of new construction projects, reduce long-term maintenance costs by reducing vegetation growth and capitalise on potential cost savings by eliminating the need for topsoil import and haulage.
The new grasslands initiative is being rolled out on all Major Projects initially, and will be implemented by Highways England’s supply chain within the Major Projects Project Control Framework on a scheme-by-scheme basis, and the aim is to apply the instruction to operational projects and wider standards in due course.
Over the last few years a number of biodiversity schemes have been undertaken by Highways England, including extensive habitat connectivity planting, species-rich grassland creation and management and a project to protect and promote the habitat of the narrow-headed ant, England’s rarest, on the A38 in Devon.
A Highways England wildflower scheme, the size of eight football pitches and visible during spring and summer along the A38 between Ashburton and Ivybridge in Devon, has won a Pollinator Award in the Big Biodiversity Challenge run by CIRIA (Construction Industry Research and Information Association). The scheme was started in 2018 with seeds from over 20 variety of flowers – including cornflowers, oxeye daisies, yellow rattle and poppies – sown over five hectares of verge, adding to 10 hectares recently created along the A38 and A30 in Devon and Cornwall.
Highways England has also been working with Cumbria Wildlife Trust, to boost pollinator habitats alongside key A roads, including the A590 and A66, and the verges and embankments of the A303 Stonehenge scheme, recently given the green light by Government, will create a flower-rich, six-mile long butterfly highway and large areas of species-rich chalk grassland.