The Pentwyn site was a sheep farm, as is much of the neighbouring land. Whilst sheep are regarded as iconic parts of the countryside, they can have a big impact on the local environment. This is largely due to their density and partly due to what and how they eat.
Sheep typically restrict fields to closely grazed grasses with little biodiversity. These rolling green hills look like they might be full of 'nature' but typically very few species are able to thrive. These landscapes have been described as 'wet deserts'.
You can see a quick comparison between the grass in 'Hilltop Corner' and a neighbouring field in this short video.
On the otherhand it is common to see livestock introduced on restoration projects. Livestock in smaller numbers, especially larger animals can help improve biodiversity. Here they acting as part of an ecosystem. They disperse seeds through their fur and dung. They create diversity by selective eating. Here it especially important that this role is filled by animals other than sheep, given they have already put strong selective pressure on what plants are there already.They also create disturbance due to their size and weight.
You can see the small herd of Belted Galloways introduced to Pentwyn in the photo at the top of the page. In the future, the aim is to introduce some pigs. These can have a dramatic impact through their digging and rummaging for food. They disturb the ground and bring seeds buried deeper underground to the surface.