Pollinators on the Verge! SRUC explores ways of getting ‘Garnock Buzzing’ again!
Insect pollinators all over the UK are struggling. The loss of flower-rich habitat has been identified as a key driver of this decline. Over the last century the UK has lost about 97% of its flower-rich meadows. This has resulted in our pollinators, such as bumble bees, butterflies, and hoverflies, not being able to find the food they need to survive.
The network of road verges that cross our countryside can provide important foraging habitat for our pollinators. However, this potential depends on how the verges are managed.
As part of the Garnock’s Buzzing project several experimental sites were established that would try to find out how, without compromising on road safety, we can best manage our road verges for our pollinators. The management of these sites included both delayed mowing (until late August/early September) and planting the verge with yellow rattle. Yellow rattle is a hemi-parasite of grasses and consequently it can help reduce grass density encouraging flowering plants to flourish.
Scotland’s Rural College (SRUC) monitored these road verges during the summer months and recorded over 1,800 pollinating insects. Eight species of bees, ten species of butterflies (including the small health – a priority species) and an impressive 40 species of hoverflies were identified. Eighty species of flowering plants were recorded from the verges including meadow vetchling, yarrow, knapweed, marsh woundwort and bird’s-foot trefoil. Bramble and bush vetch provided important forage in early summer, while later in the season most pollinators were observed foraging on marsh woundwort and knapweed. The diversity of plants on our road verges, flowered at different points in the season thus ensuring a continuous supply of pollen and nectar throughout the summer months.
Road verges are typically cut during a very narrow window, and as a result pollinators face a sudden and widespread loss of forage. Staggering mowing, for example, by only cutting one side of the road verge at a time, can help to ensure that forage is present throughout the season. Road verges are particularly profitable foraging habitats for pollinators in August. This is the period when bumblebees breed, and many pollinators are building up fat reserves to sustain them during winter hibernation.
SRUC therefore recommend that cutting should be delayed until late September when pollinators have largely finished foraging. Late mowing, however, can result in dense vegetation which could pose risk to road safety, particularly at sight lines. Furthermore, it was noted that late season cutting resulted in the formation of a dense matt of clippings. Where cut and lift machinery is not available, over time the clippings could result in nutrient enrichment potentially impacting on floristic diversity. Planting yellow rattle, has the potential to reduce grass growth and thus vegetation density which could make delayed mowing more viable. Yellow rattle establishment in the study area, however, was poor, with only a couple of plants persisting to flowering. Poor establishment could be due to the presence of more competitive flowering plants such as nettles, meadowsweet, and knapweed.
The research conducted by Garnock’s Buzzing has highlighted that road verges support rich assemblages of wildflowers, which in turn support a diversity of insect pollinators. Small changes in verge management can make a very big difference to quality and diversity of the plant communities and provide our pollinators with much needed resources to help them thrive and survive.