Parasitic plant an aid to verge management
A verge maintenance strategy which involves leaving verges to flowers and pollinators, cutting them late in the season after the flowers have finished, is to be trialled on Islay.
The concept has been promoted by wild plant conservation charity Plantlife and has already been adopted by councils up and down the country.
Islay Natural History Trust (INHT), The Botanist Foundation and Argyll and Bute Council will work together in a trial to seed areas of verge with yellow rattle, a native plant that subdues grass growth, with the goal of reducing the need for mid-season cutting.
The plan is to seed 4kms of verge around the north of Loch Gorm and Gruinart with yellow rattle this autumn.
Verge growth and development next season will be closely monitored and these areas will be cut late August or later, after the plants have seeded.
Fiona MacGillivray, INHT chairperson, said: ‘If successful, the outcome will provide longterm benefits for flowers, habitat and council budgets, creating a win-win situation for both sides of the biodiversity and budget lobby.’
INHT and The Botanist Foundation, which will fund planting and monitoring, developed the plan in discussion with council leader Robin Currie and roads and amenity team leader Julian Green.
The group also talked about verges that provide space for orchids including areas around Port Wemyss and Portnahaven and the Mulreesh road, near Finlaggan. It was agreed short sections would be left for the orchids to flower and be cut and maintained by volunteers to ensure road safety.
Fiona added: ‘Yellow rattle will be used as our catalyst for the suppression of grasses, the growth of which ultimately creates the major need for cutting. This plant is an indicator species typically found in ancient meadows. It is an annual plant and requires the ability to set seed each year to persist in the grassland.
‘It has a parasitic nature, its roots latching onto those of surrounding grasses pulling nutrients from the grass roots for its own growth, thus the grasses round these plants grow with less vigour.’
With grasses less dominant, the height of verge growth will be subdued and the need for mid-season cutting less urgent.
This will also provide an opportunity for other flowering plants like clovers to have space amongst the sward, providing more flowers for pollinating insects.
Flower-rich verges act as bridges across areas of sheep-grazed pasture and barley filled fields, linking many areas of great habitat that Islay supports.
Fiona added: ‘Our verges on Islay are a mixed bag, some all grass, rampant in growth, others a more colourful mix of flowers of varying height and some an important area for orchids and other specialist plants. Despite this variety, there is one management strategy - cutting when machinery is available and when the control of growth becomes a visible need at the end of May through to July, to provide good line of sight for drivers and for pedestrians to step off the road with safety. This cutting is welcomed by some and the loss of flowers coming into their peak cursed by others.
‘Many planting strategies promoted by Plantlife and other organisations would not fit in the Islay context. Stripping away the existing vegetation and re-seeding with flowers when our soils already have a rich and area-adapted seed bank would be expensive and intrusive.
‘Through the Pollinator Initiative, funded by The Botanist Foundation, a two-year study of less major Islay routes on the Rinns was undertaken in 2017/18 to understand the value and importance of the verges for flowers and pollinators. This work has been reported on in articles and talks. The next stage was to use this knowledge and persuade the council to adapt and change its strategy on verge management, which is now in place.
‘So next year, look out for the signs indicating verges are being left for the purposes of letting flowers flourish and enjoy the colour and beauty our rich flora provides. This is a great collaboration and hopefully one that will be the beginning of an adaptive approach to verge management on Islay and Jura.’