Upland Mixed Ashwoods

Upland mixed ashwoods occur on base-rich (alkaline) soils in the north and west of Britain. Ash is the major canopy species, although oak, birch, elm, small-leaved lime and yew may be locally abundant. Despite the variation in canopy composition, the ground flora, is broadly similar and often includes bluebells, dog’s mercury, primrose and wild garlic. The understorey usually contains hazel and various other shrubs. Upland mixed ashwoods can support a rich invertebrate fauna and lichen flora, and there are a number of rare higher plants associated with this habitat. The best examples of this habitat tend to occur on limestone, but fragments of these woodlands can develop on more acidic poorly drained soils where there is localised flushing of nutrients.

Despite the name, upland mixed ashwoods can occur at lower altitudes. The term upland merely reflects the prevalence of this woodland type on base-rich soils in upland Britain.

Current status in Carmarthenshire

It is estimated that the county contains roughly 10% of upland mixed ashwood in Wales. Although dispersed throughout Carmarthenshire, the most important concentrations lie on the narrow strip of carboniferous limestone in the south of the county, on the fringes of the South Wales Coalfield. Particularly good examples are located in the Crwbin, Drefach, Llandybie and Carmel areas. At Carmel the National Nature Reserve here holds rare plants such as herb paris and truly wild lily-of-the-valley. Small caves in the limestone are used by bats, including the rare greater horseshoe bat, with the mix of old pastures and woodlands at Carmel providing ideal insect-rich feeding habitat.

At least eight SSSIs in Carmarthenshire include areas of upland mixed ashwood. In addition much of the ash woodland at Carmel lies within the Carmel National Nature Reserve (NNR).

Current factors affecting the habitat

• Quarrying, particularly of carboniferous limestone, has destroyed and continues to threaten some sites.
• Invasion by sycamore, beech and other species, particularly since the loss of elm due to Dutch elm disease.
• Cessation of traditional woodland management, such as hazel coppicing, has led to a reduction in structural diversity in some woodlands.
• Overgrazing by sheep, deer and rabbits, leading to changes in the woodland structure, reduction of the ground flora and difficulties for regeneration.
• Air pollution is potentially a threat to the lichen communities that these woods support.
• Climatic change may result in changes in the vegetation communities.

Upland Oakwood

Upland oakwoods occur in areas of high rainfall in the west and north of Britain, on base-poor to acidic soils. They are not strictly confined to upland settings, the name reflecting the abundance of this woodland type in the more upland parts of the country. It is the most common woodland type in Wales.

Upland oakwoods are usually dominated by oak, usually sessile oak but sometimes pedunculate oak, or a hybrid of the two, with downy birch and varying amounts of ash and sycamore. Where an understorey exists this is usually a mix of hazel, holly and rowan. The ground flora varies with the underlying soils and amount of grazing, from bluebell, bramble and ferns on richer soils, to grassy swards where grazing is more intense. Heather, bilberry and mosses dominate on more acidic soils.

Many of these woodlands also contain a range of other habitats such as streams and gullies with more alkaline soils where ash may occur. Alder may be present on wetter soils, and peaty hollows are often characterised by carpets of bog mosses.

The most oceanic of these woodlands (and these include some of the Carmarthenshire upland oak woods) are particularly rich in mosses, liverworts and lichens. They also have a distinctive range of breeding birds with redstarts, pied fly catchers and wood warblers. In Wales these woods are the principal breeding areas for the red kite.

Current Status in Carmarthenshire

Carmarthenshire has 15–18% of this habitat in Wales. Most sites tend to be on the higher land in the north of the county. Particularly good examples can be found to the north of Rhandirmwyn where woods here provided a refuge for the red kite, a bird once widespread in Britain.

The demand for smelting charcoal and tan bark meant that many of these woods were intensively managed until the late 1800s. Many were felled in the two World Wars. Today, the trees in many oakwoods are nearly the same age throughout the wood – dating from the time when the wood was ‘clear felled’, then allowed to regrow without management.

At least three SSSIs in Carmarthenshire have areas of upland oakwood, including the large Cwm Doethi-Mynydd Mallaen SSSI in north Carmarthenshire. Cwm Doethi-Mynydd Mallaen SSSI also includes Allt Rhydygroes National Nature Reserve which has a fine example of upland oakwood. The RSPB Dinas Reserve near Rhandirmwyn has a good walk through the habitat.

Current Factors Affecting the Habitat

• Overgrazing by stock resulting in a decline of the ground flora and a lack of regeneration.
• Invasion by species such as rhododendron and sycamore. Rhododendron shades out the ground flora, eliminating much of its conservation interest. Invasion by sycamore can also lead to a decline in the integrity of a site.
• Unsympathetic forest management, such as restocking with inappropriate species, and failure to remove conifers where these have been planted in the past.
• Effects of air pollution especially on lichen and bryophyte communities.

Wet Woodland

Wet woodland occurs on poorly drained or seasonally wet soils, usually with alder, birch and willows as the predominant tree species, but sometimes including ash, oak and beech on the drier riparian areas. The soils that support these woodlands range from nutrient-rich mineral soils to acidic, nutrient-poor soils. Wet woodland occurs in a variety of settings: as a successional habitat on fens and bogs and around waterbodies; along streams and hillside flushes; and in floodplains. Floodplain woodland in particular is now highly fragmented through past clearance for agriculture. A long history of coppice management appears to have maintained some alder-dominated woods. Other wet woodlands have developed through natural succession on open wetlands where active management such as grazing has been abandoned.

The high humidity of some wet woodlands and the presence of saturated ground with quantities of dead wood often favours the development of rich bryophyte (moss) and invertebrate communities. Wet woodland can also provide cover and breeding sites for otters.

Current Status in Carmarthenshire

Scattered areas of wet woodland are found in the county, typically dominated by alder and various willows. Previous surveys suggest that much of this occurs as small linear stands along stream sides, often within larger blocks of drier woodland. Extensive areas of wet woodland are rare and floodplain woodland is very fragmented. It is likely that much of the wet woodland in Carmarthenshire is relatively recent.

On riverbanks wet woodlands are a retreat for otters and feeding flocks of redpolls and siskins. Rotten trees are used by the scarce lesser spotted woodpecker and their nest holes are subsequently used by other birds and bats. More extensive areas are found on hillside flushes or on ungrazed wet dunelands; indeed, the young wet woodlands on the dune system between Pendine and Laugharne may be of national significance, as wooded sand dunes are rare in western Europe.

Some wet woodlands have a long history of management – making clog soles from coppiced alder was once an important rural industry. Wet woods need careful management – modern heavy machinery can do unacceptable damage to the soil and plant life. Small-scale management for firewood, charcoal, alder poles or willow rods is often the best option.

In Carmarthenshire three SSSIs have been notified for their wet woodland; these include a total area of approximately 13 ha of wet woodland vegetation. A number of other woodland SSSIs, notified mainly for dry woodland communities, also include small stands of wet woodland.

Current Factors Affecting the Habitat

• Clearance and conversion to other land uses, particularly in woods recently established on wetland sites.
• Habitat fragmentation and loss of plant and animal species dependant on larger tracts of wet woodland.
• Abandonment of coppice management can encourage succession to drier woodland types.
• Inappropriate grazing and poaching by stock, leading to changes in the woodland structure, ground flora impoverishment and poor regeneration.
• Invasion by non-native species (e.g. Himalayan balsam) and diseases such as Phytophthora root disease of alder.
• Lowering of water tables by drainage or water abstraction, resulting in a change to drier woodland types.
• Flood prevention measures, river control and canalisation, leading to a loss of dynamic disturbance–succession systems, as well as possible reductions in the extent of individual sites.
• Poor water quality arising from eutrophication and effluents, leading to changes in the composition of ground flora and invertebrate communities.

Wood-pasture and Parkland

Wood-pastures and parklands are the products of historic land management systems, and represent a vegetation structure rather than a particular plant community. Typically they consist of large, open-grown or high forest trees – many of which are of veteran age – over a grassland habitat often grazed by cattle, deer or, sometimes, sheep. The invertebrate assemblage associated with decaying timber can be very diverse and often of exceptional value for conservation. The long-term continuity of ‘dead wood’ niches in lowland wood-pastures and parklands has resulted in significant numbers of localised or rare invertebrates being dependent upon such habitats. The lichen assemblage can also be of importance, particularly where sites are free from atmospheric pollution. Furthermore, wood-pastures and parklands are often highly valued for their historic, cultural and landscape interests.

Current Status in Carmarthenshire

The county has limited areas of wood pasture and parkland. Dinefwr Park with its veteran oaks in the Tywi Valley is the most well known, but there are others at Gelli Aur and Dan y Parc near Cynghordy. These havens for veteran trees are crucial for the rare invertebrates and lichens that only live on these aged trees. At Dinefwr, some particularly rare beetles and the pollution-intolerant lichen, lungwort, are found. Old timber, whether standing or fallen is of vital importance for wildlife.

There are also a number of smaller parkland sites which are considered to be of county importance, including Gelli Aur and Middleton Estate. Single and small aggregations of veteran trees are also considered to be of local significance.

The Dinefwr Estate is an SSSI and NNR, which is owned and managed by the National Trust and the Wildlife Trust of South and West Wales.

Current Factors Affecting the Habitat

• Loss of trees through old age and/or neglect.
• Inappropriate tree management, removing decayed limbs or whole trees, often for safety reasons.
• Lack of appropriate new plantings.
• Lack of continuity of dead wood habitat may also result in the loss specialised dependent species.
• Pollution – either remotely from atmospheric sources or directly from fertiliser or pesticide application – can also damage epiphytic lichen assemblages.

Lowland Mixed Deciduous Woodland

Lowland mixed deciduous woodland is usually dominated by pedunculate oak or ash. The soils vary from light sandy loams to heavy clays. In these woods you may come across trees not often found in the uplands – wild cherry, sweet chestnut, lime and field maple. The more acid soils often have a less varied flora – bluebell, wood anemone, honeysuckle, bramble and bracken are the commonest species. Dog’s mercury is a characteristic plant on lime-rich soils, along with enchanter’s nightshade, wood avens and arum lily.

Following centuries of management for timber, coppice products, and firewood many of these woods are now neglected. They have the potential to supply high value timber – from oak, ash and cherry which are native to these woods – and from introduced sycamore, sweet chestnut and beech which now regenerate naturally. There is however no doubt that the area of this priority type on ancient woodland sites has declined in area by clearance, overgrazing and replanting with non-native species over the last 50 years.

Current Status in Carmarthenshire

Carmarthenshire has a good proportion of this habitat in Wales. An excellent example is Castle Woods in Llandeilo. Here you can find a good range of breeding birds including great spotted, lesser spotted and green woodpecker, treecreeper, nuthatch, redstart, pied and spotted flycatcher. Resident birds of prey include sparrowhawk, buzzard and tawny owl.