Roadside Verges and Biodiversity
With a loss of biodiversity in agricultural landscapes, supporting and restoring function in the margins of these habitats is of utmost importance. In this article, we look at how roadside verges are an important feature across the landscape to support biodiversity of plant species and pollinators, as well as looking at the other ecosystem services that these habitats provide.
Recent scientific studies across Europe in countries such as England and Spain have highlighted roadsides as potential sites for biodiversity conservation. Verges tend to be grassland habitats, but also harbour: scrub, forest/woodland, scattered trees or herbaceous borders and horticultural plants. Across the UK, roadside verges range from extensive steppe like habitats, strips of disturbed land less than a few centimetres (cm) in width, to a few metres (m) of tightly or regularly mown vegetation.
Biodiversity in roadside verges
First, let’s talk about what an ecosystem service is. This is any benefit that we as humans gain from the natural function of an ecosystem. These include food provision, such as fisheries, connection to nature through national parks such as the South Downs National Park, or one of the most important, pollination.
With a shift in recent times to more agricultural landscapes, road verges often provide important sites for a wide range of plant species. Roughly half of all grassland species in the UK can be located on roadside verges with 91 species identified as either threatened or near threatened. The UK’s semi natural grassland is in serious decline, meaning the management of roadside verges could play a crucial role in preserving grassland species.
Roadside Verges and Bees
It is estimated that roughly 84% of the approximate 300 commercial crops used in global agriculture relies on insect pollination, with bees playing a major role in the pollination of fruit, vegetable and arable crops in the UK.
Bee habitat is comprised of a diverse range of flowering species and nesting substrates to support a range of generalised and specialised requirements for a myriad of species. There are approximately 270 species of bee that live across the UK. Habitat utilised by nesting bees is highly variable due to the sheer number of species found across the landscape. In addition to sources of pollen from the diverse flowering species found in verges, it is thought that roadside verges could be an important refuge for ground nesting bee species.
An increase in agricultural land has contributed to the global decline in bee populations. Creating food and nesting sources for bees is essential to save their populations and help provide the invaluable ecosystem services we rely on.
What does this mean?
Loss in pollinators is of extreme global concern. Concern for pollinator species extends beyond the area directly affected, as nations can rely on international food trade. Large, developed countries such as the UK are estimated to suffer the greatest economic losses even if pollinator losses effect less developed nations with smaller economies. Restoring and enhancing important areas around the UK is not only important for our health and economy but is globally essential.
The positive management of roadside verges can lead to increases in flowering plants and thus pollinating insects. Some studies have been completed around the UK that showcase changes in mowing frequencies can positively influence plant biodiversity. When verges are regularly mown, it doesn’t give flowering species a chance to actually come into flower. Changing this to one cut a year in late summer allows these species of plants to flower. While research is limited and in early stages, results indicate that this has a positive effect without needing to sow any seeds. It is important that any of the cuttings are removed, otherwise they break down into the soil and their nutrients encourage species of grasses to grow, which outcompete the flowering plants. Sometimes, grasses will grow faster anyway, if this happens, a cut and collect could also be carried out in early spring time.
What can you do as a homeowner?
Often, the management of roadside verges falls to the council. However, many areas of residential housing have strips of grass outside houses, some houses even have their own patch of small road verge. If you would like to make a difference, only mowing once a year at the end of summer and maybe another time in spring will encourage flowering species. If you would like to give the bees an even better chance, disturbing the ground to expose the soil will allow seeds to be sown. General wildflower mixes are great and will provide lots of beautiful flowers for the front of your house in the summer, as well as all the lovely species of butterflies and bees. Why not also think about incorporating bee and bug hotels. These also encourage ladybirds and lacewing flies, both of which are top predators for garden pests such as aphids.