Kennet Valley Alderwoods is a 56.8 hectare (140.35 acre) Site of Special Scientific Interest

Site of Special Scientific Interest

A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

 in the civil parish

Civil parish

In England, a civil parish is a territorial designation and, where they are found, the lowest tier of local government below districts and counties...

es of Welford

Welford, Berkshire

Welford is a hamlet and civil parish in the English county of Berkshire, in the valley of the River Lambourn north-west of the town of Newbury. The parish is within West Berkshire unitary authority....

 and Speen

Speen

Speen is the name of more than one place.In the United Kingdom:*Speen, Buckinghamshire*Speen, BerkshireSpeen also is a Lastname in Germany...

 in the English

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 county of Berkshire

Berkshire

Berkshire is a historic county in the South of England. It is also often referred to as the Royal County of Berkshire because of the presence of the royal residence of Windsor Castle in the county; this usage, which dates to the 19th century at least, was recognised by the Queen in 1957, and...

, notified in 1997.

Located at and at , these woodlands are the largest remaining fragments of damp, ash-alder woodland in the Kennet

River Kennet

The Kennet is a river in the south of England, and a tributary of the River Thames. The lower reaches of the river are navigable to river craft and are known as the Kennet Navigation, which, together with the Avon Navigation, the Kennet and Avon Canal and the Thames, links the cities of Bristol...

 floodplain

Floodplain

A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

. The SSSI includes two woods, the Wilderness and part of Ryott's Plantation, which are important because they support a very great diversity of plants associated with this woodland type, dominated by Alder (Alnus glutinosa), though Ash (Fraxinus excelsior) is abundant in places and there is occasional Oak

Pedunculate Oak

Quercus robur is commonly known as the Pedunculate Oak or English oak. It is native to most of Europe, and to Anatolia to the Caucasus, and also to parts of North Africa.-Taxonomy:Q...

 (Quercus robur) and Wych Elm

Wych Elm

Ulmus glabra, the Wych elm or Scots elm, has the widest range of the European elm species, from Ireland eastwards to the Urals, and from the Arctic Circle south to the mountains of the Peloponnese in Greece; it is also found in Iran...

 (Ulmus glabra). In addition to the wide range of higher plants the woods support a diverse bryophyte

Bryophyte

Bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be...

 flora including the uncommon epiphytes Radula complanata, Zygodon viridissimus and Orthotrichum affine.