Although it might not sound like a particularly fascinating topic, last February I attended a very interesting conference on road verges held just outside Ipswich at Wherstead Park.
Hosted by Suffolk Naturalists Society, there was a myriad of speakers from important wildlife organisations across the country, including Plantlife, Buglife, Butterfly Conservation, the Lincolnshire and Suffolk Wildlife Trusts and representatives from Norfolk, Suffolk, Dorset, Devon and Cornwall County Councils, all meeting to discuss the importance of road verges for wildlife and biodiversity.
It was fascinating to see how road verges are being managed in different parts of the country and what changes are likely to be beneficial to wildlife. The conference deliberations are available to be downloaded (see the Suffolk Biodiversity Information Service website) but I will try to summarise the main points and look at how they might relate to the verges in the South Yare Wildlife Group’s area.
I thought it would be useful to see what our neighbouring county to the west is doing. The Lincolnshire Wildlife Trust (LWT) has been working with the County Council. The LWT has found that bee abundance is twice as high on the roadside verges than in adjacent farm field margins, and species richness was also higher.
They have devised a Verge Quality Index and classified them as Gold (c 1%), Silver (c 10%) and Bronze (c 90%) and have come up with a tiered approach for management. Depending on road width, parallel strips are mown at different times to produce a linear mosaic. The road edge is cut and collected in May and August. The centre part of the verge is cut and collected in August while the inner part is left with standing vegetation over the winter. Where there are hedges, they are cut on a three year cycle not annually.
Lincolnshire is starting to collect the cuttings and use them in biomass digesters. This helps verge management to pay for itself. They have found a two cut cycle is more efficient for biomass yield than a four cut one. The LWT says bar mowers are less damaging than rotary machines. Most of the cuttings are removed by suction harvesters except the Gold and where possible the Silver verges where haymaking is used by raking. Suction harvesting is not ideal for insect populations but it is on balance better than cutting and leaving the residue to rot down, which keeps soil fertility high and favours the competitive grasses at the expense of wild flowers. At the parish scale the LWT recommends digging up the turf and turning it over grass side down and then planting flowers amongst it.
So, how does Norfolk County Council (NCC) compare? The Council says their policy is to cut verges along the majority of roads twice between May and September each year. The Council says up to around 1 metre of verge from the edge of the road is cut in most areas with wider areas around corners and junctions cut to make sure visibility is maintained. This policy is modified in urban areas where five cuts a year are usual. The big difference with Lincolnshire is that the cuttings are not collected and thus the soil fertility is maintained. There is no stated aim to have a linear mosaic. An exception is the 112 roadside nature reserves which are only cut in September and where volunteers rake and remove the residue.
There are some roadside nature reserves in south Norfolk but for the whole of the county the reserves only cover about 15 km of the 11,000 km of verges. The reserves can be thought of as equivalent to Lincolnshire’s Gold verges although they are much less than 1% of the total. I think that it is also true that often more than one metre (or what is needed for road safety) is cut – the approach to Thurton from the Norwich side is a fine example of this point.
The NCC says the policy is up for review in September 2020 and a Norfolk Pollinator Plan has been drafted. So this might be a good opportunity to clarify what we think we should have in the Plan and what it should say about road verges.
It is worth noting that South Norfolk is part of the ‘Clayland Region’ and a clay substrate is not as condusive to wildflower diversity as the limestone soils that bless much larger areas of Lincolnshire than Norfolk. South Norfolk claylands though are a habitat for Sulphur Clover and Crested Cow Wheat. two species of particular conservation interest.
So, what should the South Yare Wildlife Group do in its area?
I suggest we do a preliminary assessment of the verges in each parish, then select a sample to carry out a bio-audit. We might then have some data to make recommendations about management of specific areas. I think we have to realise that a lot of people are not aware of the role verges can play in helping wildlife and they think that it is good to have them cut short and looking neat and trim.
At the verge conference Plantlife gave us its Good Verge Guide which covered its five principles, tips on managing public perception and the power of community buy-in. If we had data to show how a flower rich verge compared with a frequently mown one we might find it easier to win the sceptics over in our local area.
Words by Rodney Aldis