Why grazing is so amazing

'Conservation grazing' is the use of grazing livestock to manage sites of natural importance and improve their conservation value. Here we consider why it is so important for some of Hertfordshire's wildlife

MANY of Hertfordshire’s chalk, neutral and acid grasslands, heathland and wood pastures came about as the result of livestock grazing, often over hundreds of years. In time, specialised communities of plants and animals developed to thrive in this type of habitat. Today grasslands represent some of the county’s most valuable and most vulnerable habitats and if grazing ceased they, and the specialised species they support, would eventually disappear. Under-grazing, over-grazing or changes made to the land (e.g. tree planting, roads or other developments) all present challenges to grasslands and can contribute to reducing the richness and variety of plants and animals found on a site. At HMWT we use grazing as a ‘management’ tool to help us keep our reserves looking great and suitable for the widest range of wildlife possible.

All in the balanceConservation grazing is a delicate balancing act. Overgrazing can have devastating effects, with livestock removing all the flower heads and preventing plants from growing and setting seed. Ground trampled by cattle and sheep can cause the soil to become compacted and vegetation to die off. Both problems can results in the loss of refuges for insects such as butterflies and small mammals such as voles and shrews.

Undergrazing can also be extremely harmful. Coarse, highly competitive plant species (like brambles, thistles, nettles and rush) begin to dominate, leading to a loss of the less vigorous wildflower species. Tree seedlings become established – shading out the ground flora. Within 20-40 years species-rich grassland can transform itself into densely covered, species-poor, secondary woodland.

A soft approachModern agricultural systems can prove to be too intensive for some native plants and animals – many of them have become scarce as a result. Conservation grazing is a much softer approach, maintaining (and even improving) a site’s diversity of wildlife (biodiversity). It uses fewer animals over a longer period of time (low-intensity) which is usually more beneficial than grazing large numbers of animals on a short-term basis.

Grasslands can also be managed by mowing – but this can cause sudden and dramatic changes to the habitat and have a significant negative impact. For example, heavy duty mowers can destroy ant hills – trampling by sheep does not. Visit HMWT’s Fir and Pond Woods Nature Reserve (near Potters Bar) to see anthills in the ancient meadow there – the woodpeckers really benefit from this rich source of their primary food.

Each to their ownDifferent animals help with grazing in different ways and create different habitats. Sheep nibble – grazing very close to the ground and producing short, ‘lawn like’ vegetation. Cattle can wrap their long tongues around vegetation and tear it off. They don’t graze the grass close to the ground but leave tussocks which benefit insects and small mammals. Goats prefer to browse leaves from small trees and bushes rather than graze.

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Traditional breeds of livestock have ‘harder’ mouths than modern commercial breeds and are therefore generally better for conservation grazing as they will happily munch on nettles, brambles and thistles. We use the hardy breed of Shetland sheep – introduced to the Shetland Isles by Vikings in the 8th century. To see our flock, visit our nature reserves at Patmore Heath (near Albury/Bishop’s Stortford) or Aldbury Nowers (near Tring).

A wide rangeA variety of grazing animals lend a helping ‘hoof’ on HMWT reserves including sheep, cows, horses and even water buffalo. The four Romanian water buffalo at Rye Meads Nature Reserve (near Hoddesdon) can stand the wet conditions of the meadow much better than cows and their efforts are helping to improve the site for wildlife. By removing patches of tall, rank grass, the buffalo encourage a wider range of wet meadow plants to thrive which provides the right conditions for ground nesting birds (like lapwings and redshank) to breed and raise their chicks.

It’s all about timing too: the nests and eggs of ground nesting birds can be trampled if spring grazing is too heavy, summer grazing can prevent flowers from setting seed and in autumn and winter, livestock are less likely to eat coarse vegetation as it will have become tough and woody. Heavy grazing in the winter can also destroy the habitat of overwintering insects and damage the ground – particularly during spells of wet weather.

Clearly grazing isn’t just about making sure that grasses and vegetation on our grassland nature reserves don’t get out of control. Amongst the wildlife that benefits from the attention of grazing animals, there are number of species identified in the county’s Biodiversity Action Plan (BAP). These include the dingy skipper, grizzled skipper, chalkhill blue and white letter hairstreak (butterflies); skylark, lapwing, brown hare, common lizard and slow worm. Their populations can only be increased if we improve and maintain grassland sites. So next time you see animals steadily munching away in our meadows and fields, remember that they’re not ‘taking lunch’ – they’re hard at work doing their bit to help wildlife.

HMWT has been developing conservation grazing initiatives for a number of years but once we had no need to own livestock as local farmers grazed their animals on our nature reserves. The decline in livestock farming has made this more difficult so we would be delighted to hear from anyone interested in grazing their sheep or cattle (particularly traditional breeds) on a nearby nature reserve.

To visit any of our nature reserves or to find out more about our work, contact us on 01727 858901 or visit www.hertswildlifetrust.org.uk