Sites of Special Scientific Interest, or SSSI's, are selected, and the owners are notified, by English Nature. The English Nature website contains excellent information about SSSI's ( and other activities of English Nature), and the following information is taken from the website (with permission):

"English Nature has a duty under Section 28 of the Wildlife and Countryside Act 1981 (as amended) to notify land that is of special interest for its plants, animals, geological or physiographical features. Areas of such land are called Sites of Special Scientific Interest (SSSIs)."

 

"Ever growing pressures on our landscape and countryside mean that SSSIs are an increasingly precious part of our natural heritage."

 

"There are approximately 4,100 SSSIs in England, from the south-west tip of Cornwall to the northernmost edges of Cumbria. Some are very small - about 130 are less than half a hectare. Others cover thousands of hectares - the largest is The Wash, an area of intertidal mudflats of great importance for its waterfowl and wader populations, covering 66,050 hectares."

 

"SSSIs are selected according to specific scientific criteria. The Guidelines for the Selection of Biological SSSIs, published in 1989 by the Joint Nature Conservation Committee, set down the selection criteria for biological SSSIs. These include size, fragility and naturalness of sites and the rarity of the species or habitats they support."

 

"For geological sites, 97 subject blocks have been defined. Within each block, potentially suitable sites are identified against selection criteria. The criteria are incorporated in the introductory volume of the Geological Conservation Review."

Oxshott Heath is included in the Esher Commons SSSI, and the full citation can be found on the English Nature website, including a description of the scientific criteria for selecting the area as an SSSI.