Graze anatomy: what happens when you put up a fence to keep sheep out?

Fencing small areas to keep out some of Britain's 33m sheep can allow native plants and trees to regrow, boosting biodiversity

Grazing livestock can be a key part of healthy, wildlife-rich farmland, but the number of sheep across the globe has soared, and the UK is now home to 32.7 million of them. The Peak District saw a fivefold rise in the density of sheep during the 20th century.

This has led to widespread loss of biodiversity in vast areas of the country's uplands because sheep graze the land closely (they can nibble it down to a height of 3cm), leaving less space for plants, scrub and trees to flourish.