Aldbury Nowers is a 19.7 hectares biological Site of Special Scientific Interest (SSSI) in the Chiltern Hills, north-east of Tring in Hertfordshire. The site was notified in 1990 under the Wildlife and Countryside Act 1981. It is managed by the Hertfordshire and Middlesex Wildlife Trust. The site, formerly known as "Duchie's Piece," comprises two areas of hillside, linked by The Ridgeway. The calcareous meadow element of the site hosts the flowers of chalk grassland and has butterfly habitats with thirty-four different species of butterfly recently recorded, including the Duke of Burgundy, hairstreaks and the Essex skipper. The site also includes a "beech hanger", a type of upland ancient woodland, and is considered one of the best examples of this feature in Hertfordshire.
The Turnford and Cheshunt Pits is a biological Site of Special Scientific Interest near Cheshunt in Hertfordshire and Essex and covers a total of 428.17 acres. It is part of the Lee Valley Special Protection Area.
Rye Meads is a 58.5-hectare (145-acre) biological Site of Special Scientific Interest (SSSI) in Rye House, Hoddesdon, Hertfordshire. It is one of series of wetlands and reservoirs situated along the River Lea, to the north-east of London. It is part of the Lea Valley Ramsar site and a Special Protection Area.
Frays Farm Meadows is a 28.2-hectare (70-acre) biological Site of Special Scientific Interest near Denham in the London Borough of Hillingdon. It was notified as an SSSI in 1981, and has been managed by the London Wildlife Trust on behalf of Hillingdon Council since 1999. It is part of the Colne Valley Regional Park.
Croxley Common Moor is a 39.5-hectare (98-acre) biological Site of Special Scientific Interest (SSSI) and Local Nature Reserve in Croxley Green, Hertfordshire. It is owned by Three Rivers District Council and managed by the council together with the Countryside Management Service and the Friends of Croxley Common Moor. Most of it is a registered common.
Frogmore Meadows is a 4.6-hectare (11-acre) biological Site of Special Scientific Interest in Hertfordshire and Buckinghamshire, north of the village of Chenies. It consists of two meadows in the Chilterns Area of Outstanding Natural Beauty, next to the River Chess, one of which is a Hertfordshire and Middlesex Wildlife Trust nature reserve. The planning authorities are Three Rivers District Council, Dacorum Borough Council and Chiltern District Council.
Alpine Meadow is a 0.4 hectare nature reserve near Berkhamsted in Hertfordshire in the United Kingdom. It is a designated biological Site of Special Scientific Interest (SSSI), managed by the Hertfordshire and Middlesex Wildlife Trust and the planning authority is Dacorum Borough Council.
Roughdown Common is a 3.6-hectare (8.9-acre) biological Site of Special Scientific Interest in Hemel Hempstead in Hertfordshire. The planning authority is Dacorum Borough Council. The site is Common land, and it is owned by the Box Moor Trust having been officially brought by the trust in April 1886 from the Dean and Chapter of St Paul's. It is part of the Chilterns Area of Outstanding Natural Beauty. The Common is a steeply sloping chalk hill in south Hemel Hempstead.
Hunsdon Mead is a 34 hectare biological Site of Special Scientific Interest (SSSI) west of Harlow and east of Roydon in Essex. The site is partly in Essex and partly in Hertfordshire, and it is jointly owned and managed by the Essex Wildlife Trust and the Herts and Middlesex Wildlife Trust. The SSSI also includes part of the neighbouring Roydon Mead. The planning authorities are East Hertfordshire District Council and Epping Forest District Council. Hunsdon Mead is registered common land.
Northaw Great Wood is a 223.6-hectare (553-acre) biological Site of Special Scientific Interest (SSSI) near Cuffley in Hertfordshire, England. It covers Northaw Great Wood Country Park, which is managed by Welwyn Hatfield Borough Council, Well Wood, Justice Hill and Grimes Bottom. Part of the site is managed by Hertfordshire County Council as a schools' park. The country park is also a local nature reserve.
Sawbridgeworth Marsh is a 6.3-hectare (16-acre) biological Site of Special Scientific Interest (SSSI) near Sawbridgeworth in Hertfordshire, apart from a small area in the north which is in Essex. It is managed by the Essex Wildlife Trust. The planning authorities are East Hertfordshire District Council and Uttlesford District Council.
Moor Hall Meadows is a 24.4-hectare (60-acre) biological Site of Special Scientific Interest in Moor Green in Hertfordshire. The local planning authority is East Hertfordshire District Council.
Blagrove Common is a 4.0 hectare Site of Special Scientific Interest in Green End near Sandon in Hertfordshire. It is managed by the Hertfordshire and Middlesex Wildlife Trust, and the planning authority is North Hertfordshire District Council.
Tewinbury is a 7.5-hectare (19-acre) biological Site of Special Scientific Interest near Tewin in Hertfordshire. The local planning authority is East Hertfordshire District Council, and the site is managed by the Herts and Middlesex Wildlife Trust
Aston Rowant Woods is a 209.7-hectare (518-acre) biological Site of Special Scientific Interest near Aston Rowant in Oxfordshire and Buckinghamshire. Part of it is in Aston Rowant National Nature Reserve, and a large part is in the Chiltern Beechwoods Special Area of Conservation. The site is also in the Chilterns Area of Outstanding Natural Beauty.
Long Herdon Meadow is a 4.5-hectare (11-acre) biological Site of Special Scientific Interest south of Marsh Gibbon in Buckinghamshire. It is part of Upper Ray Meadows nature reserve, which is managed by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust.
Temple Island Meadows is a 14.1-hectare (35-acre) biological Site of Special Scientific Interest on the Buckinghamshire bank of the River Thames. It is north of Henley-on-Thames and opposite Temple Island, an island in the Thames.
Wadenhoe Marsh and Achurch Meadow is a 47.5-hectare (117-acre) biological Site of Special Scientific Interest south of Wadenhoe in Northamptonshire.
