3 days ago
How these cows might save the day at popular York nature spot
DAVE POWELL talks us through an exciting new venture where cows have been deployed help battle invasive Himalayan balsam at Askham Bog
North Marsh is – you guessed it – a marsh area on the northern boundary of Askham Bog.
Askham Bog is Yorkshire Wildlife Trust's oldest nature reserve, founded in 1946 and founding – in turn - Yorkshire Naturalists' (now Wildlife) Trust.
North Marsh is approximately five acres in size, a long thin strip which sits between the north side of Far Wood and the main ditch which flows around the bog.
It's one of those hidden bits that our visitors don't see; as the reserve is surrounded on three sides by Pike Hills Golf Club, access to North Marsh is across the golf course land and then requires climbing over thick fallen willows, leaping over ditches and battling through nettles, reeds and Himalayan balsam.
North Marsh by Askham Bog in York. Photo supplied
Once upon a time, North Marsh was a nice patch of fen meadow, with various wetland species of fern, sedges, wildflowers, orchids and patches of small scrub. However, it sits between Far Wood and the main ditch, and Far Wood is being managed through a zero-management approach to study what happens to wet woodland based on acidic peat.
The issue
Over the past 20 years, Himalayan balsam – our most pervasive invasive species – has grown from unmonitored areas upstream all the way to the bottom of the system, which is where Askham Bog sits. Askham Bog provides the perfect growing medium for balsam because of its damp and largely undisturbed conditions – and its tendency to flood in winter, at which point the balsam seeds flow freely across the site.
Trying to control the Himalayan balsam at North Marsh by Askham Bog in York. Photo supplied
This year Yorkshire Wildlife Trust spent 700 hours removing Himalayan balsam from its nature reserves to no avail. Add that to just how difficult North Marsh is to access – getting people and machinery to the area takes nearly an hour each way, and the terrain is too difficult to for the golf club's grounds machinery – and at most we would only ever manage to clear a third of the area each year.
Over the years, Himalayan balsam has crept into both North Marsh and Far Wood – fragile habitats at risk of losing important and rare species. Something needed to be done – and that something, our silver bullet, is conservation grazing.
The solution
We have a herd of Dexter Cattle at Askham Bog; their nimble and energetic nature is perfect for the fen habitat, a mosaic of open and thick scrubby areas. But how could we get the cows onto North Marsh, ensure they stay there, and keep them safe and watered?
The golf club were kind enough to allow us access along their network of golf buggy tracks to get our cows most of the way there, and a good amount of scouring aerial maps found a spot where there was even enough room to have a field gate and fenced compartment.
Cows at North Marsh. Photo supplied
However, with Askham Bog being – well, a bog – this presented its own challenge. Wooden fence posts last barely five years on-site, and the cost of timber has gone up so much in recent years that it is now much closer to the cost of metal fencing. When people think of conservation, they often don't think of the nitty-gritty things like fencing – but actually, fencing takes up a lot of our time, particularly where SSSI sites like Askham Bog are involved where we need special permission from Natural England.
Fencing the way forward
For Askham Bog, we have settled on Clipex fencing; galvanised metal posts, guaranteed for 20 years and expected to last 30 years, with a system where the livestock netting can just clip onto the posts. This makes it easier to install and to maintain than traditional post and net fencing and lasts far longer. We have also taken care to design the fencing so that 3 of the 4 sides of the area have a plain wire top, meaning deer are able to freely and easily jump the fences – and have left barbed wire along the golf side to protect the cows from the golfers (or perhaps the other way round!)
Work being carried out at North Marsh by Askham Bog in York. Photo supplied
We spent 14 whole days out in North Marsh over winter, with volunteer and corporate groups, clearing trees around the boundary for the fence to go in. These trees had never been coppiced or worked on before, so it presented some of the biggest trees and limbs we've ever had to deal with.
With part of the funding from the Rural Payments Agency, we were able to install 720m of Clipex fencing, a new field gate, a new pedestrian gate – and a water line extension of nearly 350m which ran across meadows, through woods, over ditches and under culverts to spill into a brand-new trough. The scene was set, the lighting was up, and the stage was ready – all we needed was our stars.
The cows
At 7am on July 24, four brave cows entered the new North Marsh grazing compartment, wearing NoFence collars that allow us to track their progress. The goal is for these intrepid explorers to graze on the pervasive Himalayan balsam and reeds, while hopefully avoiding the ferns and sedges clinging on for survival.
If all goes to plan, our mobile lawnmowers will create a buffer strip between the main ditch, where balsam seeds will unfortunately continue to arrive, and Far Wood. This will give us a real chance to clear the balsam in Far Wood by hand without the danger of constant reinfestation – protecting the rare and fragile populations of gingerbread sedge, marsh fern and royal ferns which exist in Far Wood.
This is just the start of this restoration project, the biggest one at Askham Bog since the tree clearance of the 1990s. There will still be hundreds of hours needed in Far Wood to clear the balsam which has got in there, and we can't do this without more volunteers and corporate partners to help us.
Interested in helping us restore some of the wildest and rarest parts of Askham Bog? Find out how you can volunteer on our website at
