The steeply wooded sides of Vallis Vale support an ancient woodland community of nationally restricted distribution, although it is best developed in the Mendip Hills. In spring, the woodland is at its best, when a profusion of woodland herbs flower. Ash (Fraxinus excelsior), pedunculate oak (Quercus robur) and the local small-leaved Lime (Tilia cordata) dominate the canopy, with hazel (Coryllus avellana) and other typical limestone understorey shrubs beneath. The steep and rocky valley sides are notable for their abundance of ferns, especially hart's-tongue (Phyllitis scolopendrium) and ancient woodland herbs include wood spurge (Euphorbia amygdaloides), yellow archangel (Lamiastrum galeobdolon) and solomon's-seal (Polygonatum multiflorum).
The Mells Stream and Egford Brook meet in Vallis Vale, and the fast-flowing and clean calcareous waters support many riparian species. The American signal crayfish thrives in the river here, burrowing into the muddy banks. Some, like dipper (Cinclus cinclus) are uncommon in east Somerset, and a keen-eyed visitor may also spot kingfisher (Alcedo atthis) which also breeds nearby. Vallis Vale also supports important populations of several species of damselfly, including banded demoiselle (Calopteryx splendens) and beautiful demoiselle (Calopteryx virgo).
This old iron works beside the Mells Stream is one of the main reasons for designating the Mells Valley as a site of international ecological importance. Long disused, the stone building, and its labyrinth of flues and tunnels is now home to a large roost of greater horseshoe bats (Rhinolophus ferrumequinum), and to a lesser degree, lesser horseshoe bats (R. hipposideros). These rare bats are relatively widespread in Mendip caves and mines, and, unlike other British bats, can easily be recognised by their free-hanging roosting habit.
Mosses, liverworts and small wall ferns thrive in the diffused light and high humidity of the ruins. Brittle bladder-fern (Cystopteris fragilis) is found here close to the southermost edge of its British range, whilst the diminutive wall-rue (Asplenium ruta-muraria) and curious rustyback (Ceterach officinarum) can be found anchored in the mortar of the walls.
The narrow valley is densely wooded, and interesting herbs that can be found near the old iron works include stinking hellebore (Helleborus foetidus), and the creeping alternate-leaved golden-saxifrage (Chrysosplenium alternifolium), with its masses of attractive yellow flowers in spring in boggy ground. Limestone boulders on the steep valley sides support great masses of moss, especially Thamnobryum alopecurum and Anomodon viticulosus, and hart's-tongue is abundant on the ground, with its glossy, strap-like leaves.
Dippers and kingfishers are frequent users of the stream, feeding on small fish and invertebrates.
Asham Wood is one of the largest ancient woodlands in Mendip, and has an unusually diverse range of woodland communities, reflecting marked differences in underlying soils. Together with other ancient woodlands nearby, Asham Wood forms part of the Mendip Woods Special Area of Conservation. Two of these communities have a restricted national distribution. Ash and field maple (Acer campestre) are dominant over limestone slopes, whilst old stools of small-leaved lime, which is a notable tree characteristic of some older ash woods on Mendip, are abundant at the south-western end of the wood. Heavy acid soils over the Devonian beds support pedunculate oak, ash and coppiced hazel.
Extensive coppicing-with-standards management in the past has created many interesting stub and pollard forms of oak, lime, ash and field maple, and opened up clearings and glades in which a rich ground flora flourishes. The wood is very beautiful in spring, when carpets of flowers bloom before the canopy closes over. Dog's-mercury (Mercurialis perennis), wood anemone (Anemone nemorosa), bluebell (Hyacinthoides non-scripta) and ramsons (Allium ursinum) are typical, and the wood also supports a long list of herbs that are indicators of very old woodland. herb Paris (Paris quadrifolia), solomon's-seal and toothwort (Lathraea squamaria) thrive on the woodland floor, and the uncommon meadow saffron (Colchicum autumnale) is also widespread in parts of the wood.
Lower plants and fungi thrive in the sheltered and humid conditions. Many trees, boulders and banks support luxuriant mats of mosses and liverworts, including the distinctively flattened and wrinkled moss Neckera crispa , and the bright green Anomodon viticulosus. Soft shield-fern (Polystichum setiferum), hart's-tongue, broad buckler-fern (Dryopteris dilatata) and male fern (D. filix-mas) form attractive leafy shuttlecocks on the woodland floor, whilst many older trees and stumps sport epiphytic ferns, lichens and fungi of many kinds.
Numerous woodland birds are present, and visitors may see or hear great spotted-woodpecker (Dendrocopos major), spotted flycatcher (Muscicapa striata) and buzzard (Buteo buteo). A rich invertebrate fauna includes some notable butterflies, including purple hairstreak (Quercusia quercus) and silver-washed fritillary (Argynnis paphia).
Just east of Stoke Lane Quarry, thin mineral soils support a species-rich limestone meadow, where the sward has never been treated with fertilisers or herbicides. The old pasture is at its best in summer, when many different species of herb flower alongside grasses and sedges. Meadow oat-grass (Helictotrichon pratense), sheep's-fescue (Festuca ovina), yellow oat-grass (Trisetum flavescens), are common, along with glaucous sedge (Carex flacca), spring sedge (C. caryophyllea) and less commonly, heath-grass (Danthonia decumbens). Orchids are frequent; early purple orchid (Orchis mascula) flowers in late spring, followed in June by the pale pink spikes of common spotted orchid (Dactylorhiza fuchsii). Common rock-rose (Helianthemum nummularium) and wild thyme (Thymus polytrichus) are prostrate sub-shrubs that thrive in well-drained, warm soil, and a host of typical calcicolous herbs grow alongside: devil's-bit scabious (Succisa pratensis), fairy flax (Linum catharticum), and salad burnet (Sanguisorba minor).
Significant numbers of bats, including the nationally rare greater and lesser horseshoe bats, hibernate in the cave systems nearby.
Edford Wood is an ancient semi-natural woodland, with clay-rich soils, supporting a very interesting and attractive woodland flora. In the past, many of the trees and hazel bushes have been coppiced, allowing a rich ground flora to develop on the woodland floor. Wetter woodland along the banks of the Mells Stream is characterised by a canopy of alder (Alnus glutinosa) , with tussocks of tufted hair-grass (Deschampsia cespitosa) below. Monk's-hood (Aconitum napellus) is an unusual native in this woodland, growing in wetter areas with water avens (Geum rivale), wild daffodil (Narcissus pseudonarcissus) and ramsons.
Dog's-mercury carpets higher ground under an ash canopy, in association with many of the ancient woodland herbs that are characteristic of old Mendip woodlands. Notables include toothwort, a curious plant that parasitises hazel and other trees, wood vetch (Vicia sylvatica), solomon's-seal and early purple orchid.
Harridge Wood has an interesting history, and is thought to be very old. In the mid-twentieth century, much of the old broadleaved woodland was cleared and planted with conifers and poplars, although evidence of the older wood remains in wet areas, along the woodland edges and in isolated patches throughout the wood. Old low pollards of ash, pedunculate oak and, unusually, alder remain, known locally as 'stoggles'. Old hazel coppice is also a dominant feature in places.
Where the wood retains its semi-natural character, there is a very rich woodland flora. The distribution of species closely reflects underlying variation in geology, soil wetness and pH. Much of the wood overlies clay slopes, dissected by streams, and ferns are a distinctive feature of the woodland floor, with many different species found. Large shuttlecocks of lady fern (Athyrium filix-femina), Male fern and broad buckler-fern are abundant in very wet places. Drier ground supports a profusion of ancient woodland herbs, commonly bluebell, pignut (Conopodium majus) and Dog's-mercury. The diminutive moschatel (Adoxa moschatellina), with its unique 'town-hall clock' flower can also be found. Local plant species include sanicle (Sanicula europaea), nettle-leaved bellflower (Campanula trachelium), adder's-tongue (Ophioglossum vulgatum), herb Paris and toothwort. Common stinkhorn (Phallus impudicus) and other fungi can also be found in autumn.
Cattle-grazed pasture is juxtaposed with the wood in places, and this attracts foraging bats, including rare greater and lesser horseshoe bats, which roost in caves and buildings nearby. Daubenton's bats (Myotis daubentonii) forage along rivers and streams, particularly in the western arm of the wood. Old oak standards in the wood itself may also be important to roosting bats.
Bird-life in Harridge Wood is very diverse, and includes green woodpecker (Picus viridus), goldcrest (Regulus regulus), nuthatch (Sitta europaea) and dipper. Mammals are also well-represented by badger (Meles meles), roe deer (Capreolus capreolus) and muntjac (Muntiacus reevesii) along with wood mouse (Apodemus sylvaticus) and other widespread small mammals.