Knebworth Woods

Site of Special Scientific Interest · 51.8849, -0.2179

Also within

Hertfordshire County

Condition (Natural England)

Favourable (3) Unfavourable Recovering (3)
UnitFeatureConditionArea (ha)Assessed
TL220228 Favourable 5.98 2022-07-03
TL222229 Unfavourable Recovering 66.92 2017-04-27
TL224228 Favourable 2.39 2022-08-09
TL225213 Unfavourable Recovering 34.99 2017-04-27
TL227222 Unfavourable Recovering 66.92 2017-04-27
TL230229 Favourable 18.56 2021-04-27

Description

Area,120.8 hectares 298.5 ac Description This woodland site is of a type nationally rare, but well represented in Hertfordshire. It is a most important woodland in the north of the county lying on poorly drained acidic soils derived from underlying clay with flints. It is almost all ancient in origin and is ecologically diverse with rides, ponds and small areas of both acidic and neutral grassland. Oak Quercus robur and Oak/ hornbeam Quercus robur / Carpinus betulus are the dominant woodland types with some mixed deciduous type characteristic of south east England. In the main part of the wood coppiced hornbeam is over mature and ground flora is suppressed. Other areas such as Watery Grove are currently being coppiced resulting in diversification with ground ivy Glechoma hederacea, bugle Ajuga reptans and primrose Primula vulgaris. The mixed deciduous wood contains ash Fraxinus excelsior, downy birch Betula pubescens and aspen Populus tremula together with oak. A heathy element in the rides produces locally rare species green ribbed sedge Carex binervis and heath milkwort Polygala serpyllifolia. Small areas of the site have been felled and replanted but are currently under management to promote some regeneration of semi-natural woodland. The ponds contain two plant species rare in Hertfordshire, water voilet Hottonia palustris and fine leaved water dropwort Oenanthe aquatica. The woodland is known as a site rich in fungi and bryophytes and breeding nightingales are indicative of the diverse bird community. Burleigh Meadow, acidic grassland, supports some heathland flora including petty whin Genista anglica and Dyers Greenweed Genista tinctoria in drier areas and lousewort Pedicularis sylvatica where wetter, all three species being county rarities. The neutral grassland meadow is still the best Hertfordshire site for green winged orchid Anacamptis morio despite some limited damage in the past. The south east boundary of the meadow is formed by a line of old coppiced hornbeam.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
bugle Ajuga reptans LC herb lamiaceae
green-winged orchid Anacamptis morio NT herb orchidaceae
petty whin Genista anglica EN herb fabaceae
dyer's greenweed Genista tinctoria LC herb fabaceae
ground ivy Glechoma hederacea LC herb lamiaceae
water violet Hottonia palustris VU herb primulaceae
fine leaved water-dropwort Oenanthe aquatica VU herb apiaceae
lousewort Pedicularis sylvatica NT herb orobanchaceae
heath milkwort Polygala serpyllifolia LC herb polygalaceae
primrose Primula vulgaris LC herb primulaceae
green ribbed sedge Carex binervis LC sedge cyperaceae
downy birch Betula pubescens LC tree betulaceae
hornbeam Carpinus betulus LC tree betulaceae
ash Fraxinus excelsior LC tree oleaceae
aspen Populus tremula LC tree salicaceae
common oak Quercus robur LC tree fagaceae