Musk thistle - Paul Simmons
Yorkshire Wildlife Trust has been working extensively in an area we call the ‘invertebrate superhighway’.
The invertebrate superhighway - a narrow band of Yorkshire, is actually a ridge of magnesian limestone that runs along the eastern edge of the Pennines overlooking the Vale of York. Hosting human highways – road and rail - It also extends farther north into County Durham and south into Nottinghamshire.
Why is it so special?
The magnesian limestone ridge is a remnant of an ancient tropical sea that existed approximately 250 million years ago. Due to its geology, the ridge supports fertile soils, so some areas are farmed intensively. With increases in industry, growing urban environments and farming, many of the ridge’s specialised habitats are now under threat.
One such habitat is limestone grassland, which can still be found on the steeper, less accessible areas of the ridge that have not been intensively farmed and retain the thin limestone soils. These soils provide the right conditions for wildflower-rich grasslands; they are alkaline and free draining, which prevent coarse plant species from dominating and allow the more delicate wildflowers to flourish. The huge diversity of wildflowers supports many different invertebrates. But these grassland sites are fragmented and populations of wildflowers and invertebrates are threatened. However, with careful land management and habitat restoration, the ridge has the potential to be an invertebrate superhighway: improved habitats will support growing numbers of invertebrates, which can move north and south along the ridge to disperse and colonise new areas.
Aside from grasslands, the mosaic of other habitats along the ridge means it is attractive to many more invertebrate species. Worked-out limestone quarries, if sensitively restored or allowed to re-vegetate naturally, can support species suited to very open, rocky sites and scree. While scrub and areas of ancient woodland along the ridge provide habitat for a yet another different set of invertebrate communities.
Unlike mammals and birds, many invertebrate species have limited powers of dispersal. So it is vital that we ensure it is as easy as possible for them to move through the environment as and when they need to. Snails are a good example. The cylindrical whorl snail Truncatellina cylindrica, which is found at Brockadale and two other UK sites, will move no more than a few metres during its entire lifetime. Such species are particularly vulnerable to isolation. For instance if their small area of limestone grassland is surrounded by intensively farmed arable fields, they will not be able to disperse to new areas when they need to.
Creating a network of high quality habitats – an invertebrate superhighway – means that invertebrates will be able to move more freely, and will be better able to survive environmental changes, such alterations in temperature, or a species-specific threat, such as disease.
Our work so far
Over the last eighteen months, with support from Sita Trust, Peter Dehann Charitable Trust and The Aggregates Levy Sustainability Fund, Yorkshire Wildlife Trust has been running a pilot project to enhance, restore and create habitats along a section of the magnesian limestone ridge from Tadcaster to Maltby. By using Wildlife Trust and partners reserves within the ridge, we have developed and demonstrated practical land management techniques and best practice to other landowners and members of the local community. We have also created new areas of limestone grassland on private land previously under arable cultivation. Properly looked after and enhanced habitats can act as stepping stones, which can be buffered by the surrounding area. These buffers can be connected through further habitat improvements. And ultimately we can achieve a landscape that is joined up and rich in a variety of wildlife.
Our officers have also been raising awareness of the value and importance of the magnesian limestone ridge within local communities. They have hosted Wild Workshops on wildlife surveying and wildflower identification at Sprotbrough Flash Nature Reserve, and a workshop on grazing at Brockadale Nature Reserve to demonstrate the importance of livestock in managing limestone grasslands.
Grazing is an essential tool on many of these sites and at Sprotbrough Flash Nature Reserve we have brought in Hebridean sheep from Doncaster College’s ‘Field to Fork’ project, which aims to train students in animal husbandry and horticulture while also producing local food for Doncaster’s schoolchildren and benefitting biodiversity.