The nationally important species rich Magnesian Limestone grasslands are the most characteristic habitat of the area and are considered to be the ‘jewel in the crown’ of the region’s biodiversity.
These grasslands support an exceptionally rich diversity of plants including Common Rock Rose, Blue Moor Grass, Small Scabious, Cowslips, Dark Red Helleborine and the Fragrant, Pyramidal and Bee Orchids.
Not only are they unique to Britain but some of these grasslands are unique to the Limestone Landscapes area with the most extensive stand of primary Magnesian Limestone grassland in Britain being found at Thrislington NNR, a Special Area of Conservation (SAC).
They also support a wealth of insect life and are one of the most productive habitats in the country. The Northern Brown Argus butterfly – locally know as the Durham Argus occurs here where the caterpillar food plant, Common Rockrose is found. Other characteristic butterflies include Common Blue, Dingy Skipper, Small Copper and Ringlet. Burnet, Least Minor and Chalk Carpet moths may also be found.