The big freeze has proved a mixed blessing for rare and beautiful Arctic flowers growing in a nature reserve, according to naturalists.

Deep snow which blanketed much of rural County Durham will have formed an insulating layer over dormant plants, protecting them from hard frosts.

But the same snow has damaged fences erected to protect the plants, giving plant-nibbling animals including rabbits the opportunity to eat the new shoots or tunnel into the fragile soils and sugar limestone where they grow.

Natural England's Moor House-Upper Teesdale National Nature Reserve (NNR) in the North Pennines is of national importance for its rare Arctic flowers, some of which are survivors from the last Ice Age. Some of the plants that grow there are unique and it's the only place where the Teesdale sandwort and Teesdale rock-rose can be found.

Heather McCarty of Natural England said: "The Arctic flowers of Upper Teesdale are one of the natural wonders of North East England and help make this area one of England's top biodiversity hotspots.

"It's a botanical oasis with plants growing here that are rare survivors of the last glaciation of northern England 12,000 years ago.

"This winter's big freeze might actually be good news for these beautiful flowers as this is the kind of weather that they evolved to cope with, but their long-term future could be less certain.

"Being grazed by rabbits is one short-term risk, but there are also worries about the impact that climate change may have on our unique alpine flora.

"It's more vital than ever that we continue our environmental stewardship of this special area and keep protecting and monitoring the fortunes of its special plants."

The Natural England wardens will find out in May and June whether this year is going to be 'bloom or bust' for Teesdale's rare Ice Age survivors.