Ashridge Commons and Woods is a 640.1 hectare biological Site of Special Scientific Interest in Buckinghamshire and Hertfordshire. It is located in Little Gaddesden, and is part of the National Trust Ashridge Estate in the Chilterns Area of Outstanding Natural Beauty.
Wain Wood is an ancient woodland extending to 19.2 hectares near Preston in North Hertfordshire. The site is a Site of Special Scientific Interest which was notified in 1986 under the Wildlife and Countryside Act 1981. The local planning authority is North Hertfordshire District Council. It is a relic of a large forest which extended from Hitchin to Hatfield.
Sheepleas is a 99.9-hectare (247-acre) biological and geological Site of Special Scientific Interest east of Guildford in Surrey. It is a Geological Conservation Review site and a Local Nature Reserve. It is owned by Surrey County Council and managed by the Surrey Wildlife Trust.
Wormley-Hoddesdonpark Wood North is a 143.9-hectare (356-acre) woodland area in Hertfordshire which has been designated as a biological site of Special Scientific Interest. The site is listed as Grade 1 in A Nature Conservation Review, and is also designated a Special Area of Conservation. It is in Hoddesdon in the borough of Broxbourne, but part of the site is in East Hertfordshire.
Sherrardspark Wood is a 74.9 hectares biological site of Special Scientific Interest in Welwyn Garden City, Hertfordshire. The site was notified in 1986 under the Wildlife and Countryside Act 1981.
Westwood Quarry is a 0.07 hectares geological site of Special Scientific Interest west of Watford in Hertfordshire. It was notified in 1987 under the Wildlife and Countryside Act 1981. The planning authority is Three Rivers District Council. It is a Geological Conservation Review site.
Moor Mill Quarry, West is a 0.16-hectare (0.40-acre) geological Site of Special Scientific Interest in How Wood in Hertfordshire. The local planning authority is St Albans City and District Council. It was notified in 1992 as representing the former Moor Mill Quarry SSSI, which was lost to landfill operations. It is listed by the Geological Conservation Review.
Bricket Wood Common is a 70 hectare open space and biological Site of Special Scientific Interest in Bricket Wood in Hertfordshire. It is managed by St Albans City and District Council together with the Countryside Management Service and Bricket Wood Joint Management Committee.
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.
Benington High Wood is a 20.7-hectare (51-acre) biological Site of Special Scientific Interest in Benington, Hertfordshire. The planning authority is East Hertfordshire District Council.
Knebworth Woods is a 120.8-hectare (299-acre) biological Site of Special Scientific Interest in Knebworth, immediately south of Stevenage in Hertfordshire. The planning authority is North Hertfordshire District Council.
Bradenham Woods, Park Wood and The Coppice is a 129.1-hectare (319-acre) biological Site of Special Scientific Interest in Bradenham in Buckinghamshire. It is in the Chilterns Area of Outstanding Natural Beauty, and it is described in A Nature Conservation Review. The site is part of the Bradenham Estate, which is owned by the National Trust. It is also designated a Special Area of Conservation. Grim's Ditch, a Scheduled Monument, runs through the site.
Tring Woodlands is a 23.8-hectare (59-acre) biological Site of Special Scientific Interest in Tring in Hertfordshire. It is part of the Chilterns Area of Outstanding Natural Beauty and the local planning authority is Dacorum District Council. The wood has a rich flora, showing that it is well established. It is a good example of a semi-natural beech wood in Hertfordshire. Plants that are abundant include woodruff, wood anemone and dog's mercury, and there are a variety of woodland birds. There is access to the wood from Hastoe Hill.
Redwell Wood is a 52.8-hectare (130-acre) biological Site of Special Scientific Interest near South Mimms in Hertfordshire. The local planning authority is Welwyn Hatfield District Council.
Top Field and Cozens Grove is a 6.1 hectare Local Nature Reserve in Wormley in Hertfordshire. It is owned and managed by Broxbourne Borough Council.
Broxbourne Woods are a 239.1 hectare National Nature Reserve west of Broxbourne in Hertfordshire. The site is Hertfordshire's only National Nature Reserve, and is also a Special Area of Conservation. It covers Hoddesdonpark Wood, Wormley Wood, Broxbourne Wood and Bencroft Wood. Bencroft and Broxbourne are owned by Hertfordshire County Council, and Hoddesdonpark and Wormley Woods by the Woodland Trust. They are all in Sites of Special Scientific Interest; Wormley Wood and Bencroft Wood form almost all of Wormley-Hoddesdonpark Wood South, and Hoddesdonpark Wood and Broxbourne Wood are part of Wormley-Hoddesdonpark Wood North.
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.
