Managing Culm Grassland

Like almost all habitats in the UK, culm grassland is not entirely a natural environment. It is the result of ancient farming practices where the culm was lightly grazed or cut for hay. Swaling, where areas of land are burned with controlled fires was used to clear areas where scrub had encroached enough to reduce the grazing value of the land. Of course, none of this was done to help the environment. Low population density negated the need for intensively using all available land and without modern technology, it was not practical to manage it in any other way. This created a dynamic landscape with areas of newly grazed or newly swaled land where wildflowers were able to flourish without being shaded out by grass or scrub and other areas where scrub had encroached and created shelter for wildlife, with a range of different niche habitats in between.

The post WW2 drive for Britain to produce more food changed this situation entirely. Government grants were introduced to drain the culm, reseed it and apply fertiliser. This “improved” grassland was much more productive than the culm. The topsoil was now a mix of the peat and organic matter that had built up over hundreds of years of traditional management, combined with the best nutrients that science could provide. Unfortunately, as well as destroying valuable habitats and releasing vast amounts of carbon into the atmosphere, this form of land management left the topsoil vulnerable to being washed away, leaving just the heavy clay that originally formed the subsoil. Although the detrimental effects could already be seen, this process was continued and accelerated towards the end of the 20th century, with 50% of the culm that still existed in the early 1980’s being lost by 1991.

Since then moves have been made to restore what is left of the culm and to create species rich grassland where culm has been destroyed to provide similar habitats.

To an extent, the management of culm for environmental purposes replicates the traditional management techniques which were used before “improving” land was an option. By lightly grazing the land, or cutting the grass for hay late in the season, a balance can be found where wildflowers are able to successfully compete with the grass. If the land is not grazed or cut for hay enough, grass with shade out the wildflowers and scrub will start to encroach. If it is over-grazed, the wildflowers will go along with the grass and the diversity of the flora will be lost. Occasionally leaving the culm for a year without grazing or cutting at all for a season can help to allow wildflower seeds to set. Swaling can be appropriate where scrub has encroached too much or there is a large amount of dead vegetation. The aim should be, to create as wide a range of culm habitats as possible, from recently grazed, cut or swaled land to scrub. When the culm covered vast tracts of land and was managed traditionally, this occurred without intentional design. Now the the culm is so depleted, management has to take account of the habitats available in the surrounding landscape as well as the conditions of the particular area of land being managed.

The culm is wet and boggy and this creates issues with management. Permanent hay meadows which were cut since time immemorial with a scythe or horse drawn equipment, may suffer severe compaction if heavy machinery is used. Cattle on wet ground cause poaching, particularly when they are concentrated in one area as often happens at water troughs, gateways and when fed hay on the pasture. Unless the area of culm is particularly small or an army of volunteers is available, scything is not really a viable option. Specialist low ground compaction equipment is available, such as alpine tractors and quad-pulled machinery, and some areas of culm are considerably wetter than others, so some are more suited to cutting for hay. Lightly grazing with cattle from May to September minimises poaching.

Dividing the area of culm into smaller areas with electric fencing and moving cattle frequently has many advantages. Livestock will tend to congregate in their favourite parts of any given area of grazing, thereby causing poaching in that area. Some poaching is of benefit to certain invertebrates, but too much is is detrimental to this sensitive habitat. By dividing the grazing into smaller areas and moving them regularly, poaching is reduced. Moving water troughs around can also help with this. The smaller areas give a greater flexibility when making decisions about what to graze when. If a rare wildflower is in bloom, but not yet gone to seed, or an endangered bird is nesting in the grass in one part of the land, it is possible to leave that part until the seed has set or the fledglings have left the nest before letting cattle in to graze it, whilst still continuing to graze the rest. This style of grazing also increases soil carbon. If you let cattle roam a large area of land for a long period of time, the first area of grass that they graze will soon grow back, providing them with fresh young growth to graze This fresh young grass is much more palatable then the older grass. They will then favour this over the older grass. When the grass is first grazed, the deepest parts of its root structure are no longer required, so they die, leaving carbon in the soil. Some of this carbon will decompose and go into the atmosphere as methane, but some (especially in wet soils) will become soil carbon. If the grass is then allowed to grow, its roots also grow back and when it is grazed again, this effect is repeated, increasing soil carbon with each cycle. If instead the grass is not allowed to recover, but gets grazed again when it is young, the root structure never regrows and this opportunity to sequester carbon in the soil is lost.

Where it’s impractical to divide the area of culm into small sections, due to the terrain and manpower required, cattle or ponies can be used to graze extensively. This grazing is at a vastly lower stocking density than grazing commercially on improved pasture and mimics the traditional grazing techniques which the culm has evolved alongside. It is important that the grazing is monitored to prevent over grazing. This method will inevitably mean that some areas are more grazed than others and by the time that it is all grazed sufficiently, some areas will show signs of poaching.

Choosing the right livestock is important for culm management. Although sheep are sometimes used to prepare land for reseeding, they tend to graze too uniformly and too close to the ground and will selectively graze wildflowers rather than graze coarse grasses. Goats are fantastic for removing scrub, but tend to browse rather than graze and are therefore of little use where grazing is the requirement. Cattle and ponies are both great options for the ongoing management of the culm. Breed however is as important as species. For ponies, often semi-wild ponies such as Exmoor ponies are used, because they are hardy creatures which have evolved in a moorland environment and they are unfussy about their food. With cattle, conservation grazing generally relies on traditional breeds with a low protein requirement and low ground compaction, like the local Ruby Red cattle, Dexters and Belted Galloways. These breeds don’t poach the ground as much as more modern breeds and can survive well on the low nutritional output of rough grassland.

One of the most damaging things that you can do to culm is to drain it. No new drainage should be added and where possible, existing drainage should be restricted or blocked. This has to be carried out carefully, with regard to the surrounding land. Blocking ditches may be great for habitats on the culm which is being restored, but if it floods a neighbour’s land, a road or other amenity, it’s not going to be popular locally. It also may require tracks to be improved to ensure that the land remains accessible.

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