North Devon's Biosphere Reserve is a UNESCO-designated biosphere reserve in North Devon. It covers and is centred on Braunton Burrows, the largest sand dune system (psammosere) in England. The boundaries of the reserve follow the edges of the conjoined catchment basin of the Rivers Taw and the Torridge and stretch out to sea to include the island of Lundy. The biosphere reserve is primarily lowland farmland, and includes many protected sites including 63 Sites of Special Scientific Interest which protect habitats such as culm grassland and broadleaved woodlands. The most populous settlements in its buffer area are Barnstaple, Bideford, Northam, Ilfracombe, and Okehampton.