List of Sites of Special Scientific Interest in Hertfordshire

Hertfordshire is a county in eastern England. It is bordered by Bedfordshire to the north, Cambridgeshire to the north-east, Essex to the east, Buckinghamshire to the west and Greater London to the south. The county town is Hertford. As of 2018, the county has a population of 1,184,400[1] in an area of 634 square miles (1,640 km2).[2]

Tring Reservoirs at sunrise
Tring Reservoirs at sunrise

As of July 2019, there are 43 sites designated within this Area of Search, 36 of which have been designated for their biological interest and 7 for their geological interest.[3] In England the body responsible for designating SSSIs is Natural England, which chooses a site "because of its flora, fauna, or geological or physiographical features".[4]

Key

Sites

Site namePhotographBGArea[a]Public
access
Location[a]Other
classifications
Map[a]Citation[a]Description
Aldbury Nowers Y 19.8 hectares (49 acres)YES Tring
51°48′43″N 0°37′19″W / 51.8120°N 0.6219°W / 51.8120; -0.6219 (Aldbury Nowers)
SP951135
HMWT[5]MapCitationThe site hosts the flowers of chalk grassland and has butterfly habitats with several different species of butterfly including the Duke of Burgundy, hairstreaks and the Essex skipper. There are also large areas of woodland and calcareous grassland.[6][7]
Alpine Meadow Y 0.8 hectares (2.0 acres)YES Berkhamsted
51°46′57″N 0°34′04″W / 51.7826°N 0.5677°W / 51.7826; -0.5677 (Alpine Meadow)
SP989103
HMWT[8]MapCitationThis steeply sloping small meadow is a rare example of unimproved chalk grassland. Grass species include upright brome, false brome and sheep's fescue, and there are many orchids, especially common twayblade and common spotted orchid.[9]
Amwell Quarry Y 37.1 hectares (92 acres)YES Great Amwell
51°47′52″N 0°00′16″W / 51.7978°N 0.0045°W / 51.7978; -0.0045 (Amwell Quarry)
TL377129
HMWT,[10] SPA, SPA[11] Ramsar[12]MapCitationThis is an internationally important site for wintering wildfowl, and is Britain's most important site for dragonflies. Plants include marsh dock and hairlike pondweed, both nationally rare. Amwell has a quarter of all British species of molluscs.[10][13]
Ashridge Commons & Woods Y 627.3 hectares (1,550 acres)YESLittle Gaddesden
51°48′42″N 0°35′14″W / 51.8116°N 0.5871°W / 51.8116; -0.5871 (Ashridge Commons & Woods)
SP975135
CAONB,[14] NT[14]MapCitationThs site is mainly semi-natural vegetation, with has extensive areas of woodland, grass and scrub. There are many species of breeding birds, including some which are rare nationally, such as firecrests. Other species which are rare in Hertfordshire are common redstart, nightingale and wood warbler.[15]
Ashwell Springs Y 0.3 hectares (0.74 acres)YES Ashwell
52°02′32″N 0°08′59″W / 52.0421°N 0.1497°W / 52.0421; -0.1497 (Ashwell Springs)
TL270398
MapCitationThe site consists of a series of freshwater springs, which provide a habitat for cold water, invertebrate animals, some of which are rare. The site is particularly important for flatworms, including Crenobia alpina and the Polycelis felina.[16]
Benington High Wood Y 20.7 hectares (51 acres)YES Benington
51°53′43″N 0°08′02″W / 51.8952°N 0.1339°W / 51.8952; -0.1339 (Benington High Wood)
TL285235
MapCitationThe site is ancient woodland, described by Natural England as "one of the best remaining examples in the county of the pedunculate oak-hornbeam of the ash-maple variety". Shrub species include field maple and hazel, with a higher ground flora diversity in clearings and rides.[17]
Blagrove Common Y 5.0 hectares (12 acres)YES Sandon
51°59′12″N 0°04′13″W / 51.9868°N 0.0704°W / 51.9868; -0.0704 (Blagrove Common)
TL326338
HMWT[18]MapCitationThe site is one of the few areas of unimproved marshy grassland in east Hertfordshire. It is crossed by a stream and has a rich diversity of vegetation, including a variety of orchids.[19] Kestrels often hunt mice and voles, which are common on the site.[18]
Bricket Wood Common Y 75.5 hectares (187 acres)YES Bricket Wood
51°41′47″N 0°21′59″W / 51.6964°N 0.3664°W / 51.6964; -0.3664 (Bricket Wood Common)
TL130010
MapCitationThe common is a remnant of a lowland heath, with much it on the heavy soils of boulder clay which have poor drainage and wet habitats. There are also areas of ancient woodland and dry heath. In drier heath areas there are heather, purple moor-grass and heath milkwort.[20]
Castle Lime Works Quarry Y 1.4 hectares (3.5 acres)NO South Mimms
51°42′31″N 0°13′22″W / 51.7087°N 0.2227°W / 51.7087; -0.2227 (Castle Lime Works Quarry)
TL229026
GCR[21]MapCitationNatural England states: "This reveals extensive piping in the top of the chalk resulting from solution at the Chalk - Tertiary sediment interface. Believed to have formed during the Tertiary and Pleistocene, it is the finest exposure of clay-filled pipes in the Chalk Karst of England."[22]
Croxley Common Moor Y 39.6 hectares (98 acres)YES Croxley Green
51°38′33″N 0°26′11″W / 51.6425°N 0.4363°W / 51.6425; -0.4363 (Croxley Common Moor)
TQ083949
LNR[23]MapCitationThe site is mainly grass heathland with some ancient woodland and hazel coppice. Over 250 species of plants have been recorded, including sheep sorrel, common bent and sheep's fescue. There are many ant hills made by yellow meadow ants.[24][23]
Downfield Pit, Westmill Y 0.3 hectares (0.74 acres)YES Ware
51°49′51″N 0°02′37″W / 51.8308°N 0.0437°W / 51.8308; -0.0437 (Downfield Pit, Westmill)
TL349165
MapCitationThe site provides an example of the complex sequence of Pleistocene gravels and clays laid down by the River Thames when it flowed through the Vale of St Albans before the river was diverted south by the Anglian ice age around 450,000 years ago.[25]
Frogmore Meadows Y 4.6 hectares (11 acres)YES Chenies
51°40′47″N 0°31′29″W / 51.6796°N 0.5247°W / 51.6796; -0.5247 (Frogmore Meadows)
TQ021989
CAONB,[26] HMWT,[27]MapCitationThe site has marshy areas and fens next to the river, damp grassland and drier, more acidic areas. The river bank has water voles, and damp areas are dominated by meadow foxtail and Yorkshire fog, with some marsh marigold and marsh bedstraw.[28][27]
Great Hormead Park Y 15.0 hectares (37 acres)YES Great Hormead
51°56′36″N 0°03′42″E / 51.9432°N 0.0616°E / 51.9432; 0.0616 (Great Hormead Park)
TL418292
MapCitationThe site is coppiced ancient woodland on boulder clay. It has diverse tree species, including wych elm and hornbeam, resulting in a rich ground flora. Dog's mercury is dominant over most of the woodland floor, with plants such as angelica sylvestris and tufted hair grass in wetter areas.[29]
Hertford Heath Y 29.1 hectares (72 acres)YES Hertford Heath
51°46′53″N 0°02′14″W / 51.7813°N 0.0372°W / 51.7813; -0.0372 (Hertford Heath)
TL355110 &
TL350106
HMWT[30]MapCitationThe heath is dominated by heather, and there are grass snakes and slow worms. Sphagnum mosses and creeping willow are found in wetter areas. Ponds support the rare water violet and a rich invertebrate fauna such as great crested and smooth newts, the water spider and eight species of dragonfly.[31][30]
Hillcollins Pit Y 0.2 hectares (0.49 acres)YES Furneux Pelham
51°55′16″N 0°05′43″E / 51.9211°N 0.0954°E / 51.9211; 0.0954 (Hillcollins Pit)
TL442268
GCR[32]MapCitationThis disused gravel pit is the type site for the Westland Green Gravels, which were laid down by the ancestral River Thames 1.6 to 1.8 million years ago, and which show the river's ancient course.[33]
Hunsdon Mead Y 34.2 hectares (85 acres)YES Harlow
51°46′47″N 0°03′15″E / 51.7797°N 0.0541°E / 51.7797; 0.0541 (Hunsdon Mead)
TL418110
HMWT[34]MapCitationThis is unimproved grassland which is subject to winter flooding. Notable grass species include meadow brome and the quaking grass briza media, and there are other unusual flora such as pepper saxifrage and green-winged orchid.[35]
Knebworth Woods Y 128.8 hectares (318 acres)YES Stevenage
51°53′09″N 0°13′02″W / 51.8857°N 0.2172°W / 51.8857; -0.2172 (Knebworth Woods)
TL228223
MapCitationThe wood is ancient in origin and ecologically diverse. The dominant trees are oak and hornbeam. Ponds have unusual plant species, and the site is rich in fungi and bryophytes. Breeding birds include nightingales.[36]
Little Heath Pit Y 1.2 hectares (3.0 acres)YES Potten End
51°45′48″N 0°31′40″W / 51.7633°N 0.5278°W / 51.7633; -0.5278 (Little Heath Pit)
TL017082
GCR,[37] NT[38]MapCitationThe lowest layer is gravel dating to the beginning of the Pleistocene 2.6 million years ago. A higher layer of gravel was laid down some 20,000 years ago, when the last ice age was at its maximum, and the site was cold tundra like western Siberia today.[39]
Moor Hall Meadows Y 24.0 hectares (59 acres)YES Ardeley
51°55′16″N 0°04′03″W / 51.9211°N 0.0674°W / 51.9211; -0.0674 (Moor Hall Meadows)
TL330265
MapCitationThe site has a variety of types of meadows, with marshy grassland being the most extensive. Its rich flora makes it one of the most important grassland sites in the county. There is also a small ancient woodland which has a variety of breeding birds.[40]
Moor Mill Quarry, West Y 0.2 hectares (0.49 acres)NO How Wood
51°42′43″N 0°21′02″W / 51.7119°N 0.3506°W / 51.7119; -0.3506 (Moor Mill Quarry, West)
TL141027
GCR[41]MapCitationThe pit displays the advance of ice during the Anglian glaciation around 450,000 years ago, which diverted the Thames south to its present course. The site is regarded by Natural England as of fundamental importance as the only one which demonstrates the diversion of the Thames from its pre-Anglian course.[42]
Northaw Great Wood Y 224.3 hectares (554 acres)YES Cuffley
51°43′22″N 0°08′54″W / 51.7228°N 0.1483°W / 51.7228; -0.1483 (Northaw Great Wood)
TL280043
LNR[43]MapCitationThe site has one of the county's most extensive areas of ancient hornbeam woodland, with other trees including oak and silver birch. Glades, streams and springs add to the biodiversity.[44]
Oddy Hill and Tring Park Y 36.0 hectares (89 acres)YES Tring
51°47′20″N 0°38′50″W / 51.7890°N 0.6473°W / 51.7890; -0.6473 (Oddy Hill)
SP934109
51°47′01″N 0°39′22″W / 51.7837°N 0.6561°W / 51.7837; -0.6561 (Tring Park)
SP928103
RHPG.[45]MapCitationThis is one of the most extensive areas of unimproved chalk downland in Hertfordshire. The site has diverse grass and flowering plant species. Orchids include common spotted-orchid, common twayblade, greater butterfly-orchid and southern marsh-orchid.[46]
Oughtonhead Lane Y 1.0 hectare (2.5 acres)YES Hitchin
51°57′19″N 0°17′45″W / 51.9552°N 0.2959°W / 51.9552; -0.2959 (Oughtonhead Lane)
TL172299
GCR[47]MapCitationThe site probably dates to the Hoxnian interglacial 420,000 to 300,000 years ago. It was then a marsh fed by springs, and it has a tufa which contains fossil land snails and mammal bones which show the climate and local environmental conditions.[48]
Patmore Heath Y 8.5 hectares (21 acres)YES Albury
51°54′43″N 0°05′47″E / 51.9120°N 0.0965°E / 51.9120; 0.0965 (Patmore Heath)
TL443258
HMWT[49]MapCitationThe site is home to a large amount of dry grass, as well as marshy-areas. Much of the turf is dominated by Deschampsia, as well as occurrences of Anthoxanthum odoratum. Uncommon plants are heath rush and heath grass. There are a wide variety of dragonfly, including the emperor dragonfly.[50]
Plashes Wood Y 73.2 hectares (181 acres)YESStandon
51°52′01″N 0°00′21″E / 51.8669°N 0.0058°E / 51.8669; 0.0058 (Plashes Wood)
TL382206
MapCitationThe site is mainly oak and hornbeam woodland near the northern limit of its natural distribution. It has varied ground flora on soils from damp heavy clay to light gravels. There are also ponds and extensive clearings dominated by bracken, and other flora including hoary cinquefoil.[51]
Redwell Wood Y 52.6 hectares (130 acres)YES South Mimms
51°42′29″N 0°14′45″W / 51.7081°N 0.2459°W / 51.7081; -0.2459 (Redwell Wood)
TL213025
MapCitationThe site has ancient and secondary woodland, heath and scrub. The woodland canopy is dominated by pedunculate oak. Ground flora include bluebells and enchanter's-nightshade, while heathland species include heather and the rare creeping willow.[52]
Roughdown Common Y 3.7 hectares (9.1 acres)YES Hemel Hempstead
51°44′25″N 0°29′06″W / 51.7402°N 0.4850°W / 51.7402; -0.4850 (Roughdown Common)
TL047057
CAONB[53]MapCitationThis is one of the few examples of unimproved calcareous grassland in Hertfordshire. The dominant grasses are meadow fescue and meadow oat-grass, and there are colonies of orchids. It is the only site in the county where common juniper regenerates naturally.[54][53]
Rye Meads Y 60.3 hectares (149 acres)YES Rye House
51°46′34″N 0°00′22″E / 51.7760°N 0.0061°E / 51.7760; 0.0061 (Rye Meads)
TL385105
Ramsar,[55] SPA[11] RSPB,[55] HMWT[56]MapCitationPart of this site is an ancient flood meadow which has a variety of habitats including reedbed, marshy grassland and fen. It is grazed by ponies and water buffalo.[56] There are also ponds which have kingfisher, snipe, green sandpiper, shoveler, gadwall and tufted duck.[57]
Sarratt Bottom Y 3.5 hectares (8.6 acres)NO Sarratt
51°40′46″N 0°30′37″W / 51.6794°N 0.5102°W / 51.6794; -0.5102 (Sarratt Bottom)
TQ031989
MapCitationThe site is a meadow beside the River Chess. It is an example of damp grassland which has been traditionally managed for grazing. There are also areas of swamp and marsh. The main plants in grassland areas include sweet vernal grass and meadow foxtail, and marsh horsetail and common spike-rush are common in damper areas.[58]
Sawbridgeworth Marsh Y 6.2 hectares (15 acres)YES Sawbridgeworth
51°49′15″N 0°09′48″E / 51.8209°N 0.1634°E / 51.8209; 0.1634 (Sawbridgeworth Marsh)
TL492158
EWT[59]MapCitationThe site is a river valley marsh close to the River Stort, which has a varied wetland flora. Grazing and cutting of the marsh in rotation maintain biological diversity. The site also has an important wetland fauna and many moth species.[60]
Sherrardspark Wood Y 74.4 hectares (184 acres)YES Welwyn Garden City
51°48′37″N 0°13′02″W / 51.8102°N 0.2172°W / 51.8102; -0.2172 (Sherrardspark Wood)
TL230139
LNR[61]MapCitationThe site is an ancient semi-natural sessile oak and hornbeam wood on acid soils. There are also swallowholes fed by streams, and a woodland ride provides a habitat for invertebrates.[62]
Tewinbury Y 7.3 hectares (18 acres)NO Tewin
51°48′34″N 0°10′04″W / 51.8095°N 0.1679°W / 51.8095; -0.1679 (Tewinbury)
TL264139
HMWT[63]MapCitationThe site borders the River Mimram. It has alluvial meadows and marshes which are rare in lowland Britain. There are areas of swamp and tall fens, with plants including butterbur and angelica. Otters have been observed on the riverbank, in possibly the only site in the county.[64][63]
Therfield Heath Y 146.5 hectares (362 acres)YES Therfield
52°02′32″N 0°03′18″W / 52.0423°N 0.0549°W / 52.0423; -0.0549 (Therfield Heath)
TL335400
LNR,[65] SM[66][67]MapCitationThis site is described by Natural England as describing some to the richest chalkland in England. It is unimproved pasture which has a wide variety of plants including the rare pasque flower. There is a diverse insect fauna.[68]
Thorley Flood Pound Y 17.3 hectares (43 acres)YES Thorley
51°50′36″N 0°09′41″E / 51.8434°N 0.1615°E / 51.8434; 0.1615 (Thorley Flood Pound)
TL490183
HMWT[69]MapCitationHabitats include tall wash grassland, which is now rare, marsh and waterlogged grassland. It has a wide variety of plant species, including reed sweet-grass and meadowsweet. There are flowers such as fen bedstraw and early marsh orchid. Breeding birds include snipe and water rails.[70]
Tring Reservoirs Y 100.0 hectares (247 acres)YES Tring
51°48′49″N 0°40′06″W / 51.8135°N 0.6683°W / 51.8135; -0.6683 (Tring Reservoirs)
SP919136
SP905131
HMWT[71]MapCitationThese four reservoirs are on the sites of ancient marshes, and their diverse fauna and flora include some dating back to their marshland origins. The site is important for breeding and wintering birds, including nationally important numbers of shovelers. The site is also significant for invertebrates.[72]
Tring Woodlands Y 24.1 hectares (60 acres)YES Tring
51°46′52″N 0°40′20″W / 51.7812°N 0.6721°W / 51.7812; -0.6721 (Tring Woodlands)
SP917100
CAONB[73]MapCitationThe wood has a rich flora, showing that it is well established. It is one of the best examples of semi-natural beech woodland in Hertfordshire. Plants include woodruff, wood anemone and dog's mercury, and there is a variety of woodland birds.[74]
Turnford and Cheshunt Pits Y 174.4 hectares (431 acres)YES Cheshunt
51°42′32″N 0°01′07″W / 51.7090°N 0.0186°W / 51.7090; -0.0186 (Turnford & Cheshunt Pits)
TL370030
SPA[11]MapCitationThis site includes ten former gravel pits, which are of national importance for wintering gadwalls and shovelers. It is also valuable for invertebrates, especially grasshoppers and bush-crickets.[75]
Wain Wood Y 19.0 hectares (47 acres)YES Preston
51°54′56″N 0°17′09″W / 51.9155°N 0.2858°W / 51.9155; -0.2858 (Wain Wood)
TL180255
MapCitationThe wood lies on a north-east facing slope of decalcified boulder clay. The woodland area is also home to pedunculate oak and Quercus petraea, with much of the south of the area consisting of acidic grassland. There are many butterfly species, including Thecla quercus.[76]
Water End Swallow Holes Y 11.1 hectares (27 acres)YESWelham Green
51°43′26″N 0°13′14″W / 51.7239°N 0.2206°W / 51.7239; -0.2206 (Water End Swallow Holes)
TL230043
MapCitationThe site covers more than fifteen sinkholes, the only ones in chalk which are a permanent feature of the landscape. Next to the holes is a swamp area of willow carr which is biologically important, and in deep water there is reed sweet-grass. The site also has areas of woodland and grassland.[77]
Westwood Quarry Y 0.1 hectares (0.25 acres)NO Watford
51°40′56″N 0°27′08″W / 51.6823°N 0.4523°W / 51.6823; -0.4523 (Westwood Quarry)
TQ071993
GCR[78]MapCitationThis site throws light on the early history of the River Thames, when it flowed through the Vale of St Albans, before it was diverted south to its present course during the Anglian Ice Age around 450,000 years ago.[79]
Whippendell Wood Y 66.7 hectares (165 acres)YESWatford
51°40′07″N 0°26′44″W / 51.6687°N 0.4455°W / 51.6687; -0.4455 (Whippendell Wood)
TQ076978
MapCitationThis is ancient woodland, and the main trees are oak, ash, hazel and hornbeam. Ground flora include Yorkshire fog, bluebells and honeysuckle. There are diverse species of fungi, invertebrates and birds.[80]
Wormley-Hoddesdonpark Wood North Y 143.9 hectares (356 acres)YES Hoddesdon
51°45′32″N 0°02′33″W / 51.7589°N 0.0425°W / 51.7589; -0.0425 (Wormley-Hoddesdonpark Wood North)
TL352085
TL325075
NNR,[81] WT,[81] NCR,[82] HMWT,[83] SAC[84]MapCitationThe site is oak and hornbeam on acid gravel. The ground flora is diverse, including dog's mercury and yellow archangel. Small ponds and streams are important for bryophytes, and invertebrates include the green tiger beetle.[82]
Wormley-Hoddesdonpark Wood South Y 196.2 hectares (485 acres)YES Cheshunt
51°44′39″N 0°04′25″W / 51.7441°N 0.0735°W / 51.7441; -0.0735 (Wormley-Hoddesdonpark Wood South)
TL331068
NNR,[85] NCR,[86] SAC[84]MapCitationThe site is oak and hornbeam woodland mainly on London clay. Plants in the variable ground flora include brambles, wood anemones and bluebells. Other habitats include marshland and acidic grassland.[86]

See also

Notes

References