PUBLISHED: 10:02 18 October 2015
Using grazing animals has become a key tool in managing rare grassland habitats. Herts and Middlesex Wildlife Trust reserves manager Paul Thrush explains
If you have been lucky enough to visit a well-managed traditional grassland this spring or summer, perhaps at one of the Herts and Middlesex Wildlife Trust reserves, it’s likely you will have been overwhelmed by the diversity of life there. Rare orchids, vetches, cowslips and sedges are studded throughout the sward. In less well-drained areas you might have found ragged robin, meadow rue, marsh marigold and cuckooflower. The vibrant colours of these flowers attract butterflies as well as our most endangered and important pollinator, the bumblebee. Wildflowers have evolved to take advantage of niches, such as nutrient-poor soils, where other plants struggle. Soils with high levels of nutrients generally favour common plants such as rank grasses, nettles and thistles –aggressive competitors that crowd out rarer species.
Until only a few decades ago, these grassland habitats were so abundant they were overlooked by conservationists. However, species-rich grassland became rare and threatened as farming practices changed and they were ploughed up and nutrients added to the soils to make them more productive. In Hertfordshire, we are lucky to have remnants of grassland which escaped this. From floodplains in river valleys to chalk grasslands in the Chilterns, these contain species-rich habitats. Traditional management such as hay cutting and grazing helps to maintain these grassland areas in a low-nutrient state by removing the build-up of growth which occurs during spring and summer. Where these practices are reintroduced on unimproved land with poor nutrient conditions, the resulting species diversity can be spectacular. An unmanaged grassland will quickly become a dense overgrown sward of common grasses, nettles and thistles, and then impenetrable scrub. Grazing is often the best option to maintenance but it has to be the right kind, at the right levels, at the right time. Different types of animals graze differently, and can have very different effects on vegetation.
Sheep tend to be used during autumn and winter at Aldbury Nowers, Amwell, Patmore Heath and Fir and Pond woods reserves. They tend to nibble plants, grazing very close to the ground to create a short sward. They actively seek out the tastiest flower heads and buds and some breeds struggle on tall or rough vegetation. They are very light, so tend not to disturb the ground too much. In addition, they are easy to handle, and to move into specific areas where targeted grazing is needed.
Cattle can be found from mid-summer to autumn at Thorley Wash, Blagrove Common and Long Deans reserves. Cattle wrap their tongues around a tuft of vegetation and pull it into their mouths, which creates a very different sward structure to sheep grazing. They don’t seek out tasty morsels, and instead graze a site in fairly uniform way, munching pretty much everything they come across. They are a lot heavier than sheep, and, while too many can erode the ground, some hoof marks are valuable both to create bare soil to allow seed germination and as micro-habitats for invertebrates.
Four konik ponies are moved around the trust’s large wetland sites such as Amwell and Rye Meads. As a rule they are at Amwell throughout the winter and at Rye Meads in summer. Koniks are a hardy breed that copes well on rough sites. They are quite selective grazers, which means they can create a diverse sward with lots of variation in structure.
By October, grasslands can look a little dull, but conservation is still at work. The trust’s living lawnmowers will be out there grazing, and the team of reserve officers and volunteers will be cutting and raking. Come next spring it will all be worth it, as once again the meadows burst into life, reminding us why these are habitats to be proud of and why we need to take care of them.