Carmarthenshire Habitats

CARMARTHENSHIRE WOODLANDS

Woodlands and forests cover about one-seventh of Carmarthenshire. Pick one and you will usually find that it falls into one of two quite separate groups. These two types of woodland have different types of tree, different uses and different histories.

Plantations of introduced conifers (and occasionally non-native broadleaves like red oak) make up about 70% of the total area. Most of these woodlands have been planted since 1940. They cover large areas in the uplands, have replaced native woodlands along some valley sides and have been planted on reclaimed industrial land.

More than half of the trees are Sitka spruce. The rest include Norway spruce (the traditional Christmas tree), larches, pines and Douglas fir. More than half are owned and managed by Forestry Commission Wales on behalf of the Welsh Assembly Government.

Native woodlands make up the remaining 30% of our woodlands. They are scattered throughout the Welsh countryside, often on land that was too difficult or too poor to clear for agriculture. Many are the remnants of the native, broadleaved woodland that once covered much of Wales. Oak is the commonest tree, with ash, beech, sycamore, birch and alder making up most of the rest. Yew, the only conifer native to Carmarthenshire, is found wild in a few woodlands. Most native woodlands are privately owned, many by farmers. They are often small, covering just a few hectares. In the past many were intensively managed for a wide range of products.

Our forests and woodlands do much more than provide us with timber. Much of our wildlife depends upon them. Carmarthenshire has Habitat Action Plans for Upland Oakwood, Upland Mixed Ashwoods, Wet Woodland and Lowland Wood-pasture and Parkland. There are Species Action Plans for some of our rarest woodland species including dormouse, red squirrel and red kite.

Woodlands and forests are also valuable places for recreation and education and are an important part of the Carmarthenshire landscape. They generate employment and, by absorbing and storing carbon dioxide, play their part in fighting climate change.

WOODLAND MANAGEMENT

Coniferous and broadleaved woodlands have traditionally been managed in different ways.

Conifer forests have usually been planted, left to grow for between 40 and 60 years, clear felled and then replanted. The huge expansion of this type of woodland during the 20th Century followed timber shortages during the two World Wars. Today most coniferous timber (often called softwood) is used to manufacture chipboard, paper and cardboard and by local businesses producing sawn timber, fencing and other products. Although originally established to grow timber many of these forests are now managed for recreation and wildlife too.

Our native, broadleaved woodlands were an important part of the local economy for hundreds of years. They provided our ancestors with timber for building, materials for craftspeople, charcoal for smelting, oak bark for tanning, firewood and much more. Most have now lost that role and often have been unmanaged for many years. Many were felled during the first half of the 20th Century, then cleared for agriculture, replanted with conifers or left to regrow unmanaged from stumps or seed. Initiatives such as Coed Cymru and a range of grants from Forestry Commission Wales have encouraged many woodland owners to managing their native woodlands. Some of the woodlands felled and planted with conifers in the last century are now being restored as native woodland.

Managing a woodland can be a great help to biodiversity. Thinning will produce bigger trees more quickly, help to improve the balance of tree species and let in more light to encourage woodland plants and young trees. Coppicing will open up temporary glades in the woodland and encourage birds, butterflies and other wildlife. Management needs to be carefully controlled. New track routes need to be cut where they will do the least damage. Old, dead and dying trees, vital for woodpeckers, beetles and other woodland wildlife need to be kept wherever possible. The best woodland for biodiversity is often one with a bit of everything – trees of all ages from seedling to veteran, plenty of different species, damp areas, dark areas, sunny areas, grasses, brambles, spring flowers, dry banks, stony banks, mossy banks.

NEW WOODLANDS

NATIVE WOODLAND TREES

Oak

Sessile oak (Quercus petraea) and pedunculate or English oak (Quercus robur) are our two native oaks. They are common throughout Wales, although sessile oak is more associated with the western uplands. They are slow growing, light demanding and dislike frost and exposure. They will grow in most soil types, provided the soil is deep enough to root in. Initially growth is slow, so oak tends to suffer from competition from other plants during its early life.

Oak responds very well to thinning and will develop and build a crown if other trees do not crowd it. Both species begin to yield seed between the ages of 35-50, and oak coppice shoots can produce acorns 20 years after the stools are cut. Most prolific seeding occurs when the trees are 80-120 years old depending on site and climatic conditions. Seed is not produced prolifically every year, rather at intervals of 3-4 years for pedunculate oak, and 4-5 years for sessile oak. These seed years are termed 'mast' years, and seed produced between mast years is often poor, or absent altogether.

Ash

Ash (Fraxinus excelsior) is found throughout Wales, and is a very important woodland species. It occurrs mostly in lowlands, but it will survive at higher altitudes than oak. It prefers moist, deep, fertile, freely draining calcareous soils, or peat-free hillsides over limestone and base-rich fenland.

The ash, like the oak, is frost tender and light demanding. It regenerates prolifically, coppices freely and grows well in mixtures with oak, beech and sycamore. Ash grows quickly as a young tree with the growth peaking at age 20-25 years, stabilising at 40-45 and slowing to a minimum at 60 years and beyond. Seed production follows a similar pattern, with the first good crop of winged ash 'keys' coming at age 25-30 reaching a maximum at 40-60 years. The production of keys is not cyclical and good seed is produced in most years. Ash seedlings can withstand moderate shade but the growing tree is light demanding requiring overhead light and side shelter. Unlike oak it will not respond well to thinning if the crown has been restricted by competition. Ash is susceptible to frost damage, which causes forking in the mature tree and bacterial cancer which leads to degradation of the stem&.

Birch

Both silver birch (Betula pendula) and downy birch (Betula pubescens) are native to Wales and are widespread colonising waste ground, felled woodlands, heath and moorland. Birch is renowned for its pioneering light demanding habit, and its ability to grow on a multitude of soil types and locations.

Slower growing downy birch appears more suited to the poorly drained peaty soils of the Welsh uplands. Birch is extremely frost hardy and tolerant of exposure. It acts as a soil improver and the leaf litter reduces soil acidity. Young trees coppice freely and will usually recover from fire damage by producing new basal shoots. Young trees are vulnerable to browsing damage by farm stock, deer and small mammals. Birch produces large quantities of seed from a young age. It is light and airborne which enables it to colonise bare sites readily but it struggles to compete with existing ground vegetation except heather. Birch is a fast growing, short lived species, growing rapidly for the first 20 years reaching maturity at 40-50 years and slowing to death at 60-80 years. Areas of pure birch have the tendency to self-thin and do not respond well to thinning operations after canopy closure.

Beech

Although a native of southern England and south east Wales, beech (Fagus sylvatica) can be found throughout Wales where it has become naturalised from planted stock. Beech is tolerant of shade, it is frost tender and dislikes waterlogged conditions.

It is often associated with alkaline soils, but it will tolerate a wide range of soils and sites. It regenerates freely under the canopies of other trees and is often found in dense groups growing very slowly in extremes of light and nutrient competition. Seeding is also poor under a closed canopy, with little seed produced before the tree is 60 years old, sooner in an open grown tree. Production of seed reaches a maximum at age 80-140 and seeding may continue until the tree is 200 years of age. Mast years occur at irregular 5-15 year intervals and are believed to be associated with warm dry summers. Because of its need for the shelter of other trees and frost tenderness beech is not an ideal species for planting on open ground. It is better as an understorey crop. It responds well to thinning, providing the crowns are big enough to recover. Young beech tends to hold its leaves during the winter which along with its shade bearing qualities and ability to withstand exposure make it ideally suited to shelter belts and windbreaks. Planting of beech in large quantities is not recommended as it suffers from a variety of fungal and bacterial diseases. It is often attacked by grey squirrels which strip the bark, causing serious timber defects and opening wounds for invasion of bacteria and fungi.

Sycamore

Sycamore (Acer pseudoplatanus) is a non-native tree, probably introduced to Wales before the 17th Century and has now become naturalised. It is moderately shade bearing as a sapling, requiring full light as it grows. It can tolerate exposure to wind, salt spray and air pollution hence its suitability for use in shelterbelts and wind breaks.

It will survive on most soil types but prefers deep well drained soils over chalk or limestone or acid brown earth. It is moderately susceptible to frost damage. Sycamore coppices well and regenerates freely, growing rapidly in the first 25 years of its life. It is often found in mixture with wild cherry, beech and ash or as a single species. Sycamore responds well to regular thinning to keep the crown deep and the growth vigorous. It is longer lived then other maples reaching maturity at 75+ years and can live well into its 100's. Grey squirrels will strip the bark and damage to the tree and timber can be significant if uncontrolled. The invasive nature of the regeneration can stifle the growth of other saplings particularly oak, and mature trees cast heavy shade which suppresses ground flora. It should not be introduced into native broadleaf woods where it is not already present.

Alder

Alder (Alnus glutinosa) is found naturally throughout Wales usually on wet sites besides streams and marshes on soil of most types although it grows poorly on acidic peaty ground. Alder is able to fix its own nitrogen using micro-organisms that live in its root nodules. It is therefore a very important species on industrial reclamation sites and soils where nitrogen is lacking. Alder is a light demander which regenerates freely on wet exposed soil. It grows well in mixtures with ash, hazel and birch or will grow as a pure stand.

It is a useful nurse to oak on heavy soil, coppices well, is hardy to frost and is deep rooting and wind firm. These characteristics make is a useful tree in shelter belts particularly as it is not that palatable to grazing animals.

Alder seedlings require moisture to establish, so regeneration is only successful in areas that remain damp through the spring and summer months. Growth is rapid for the first 20 years with maturity reached at 30-40 years. Growth is negligible at 60 years and above. Planted alder also does well on drier sites.

Wild cherry

Wild cherry or gean (Prunus avium) is native to Wales occurring as a minor component on the edge of existing woodland, particularly with oak and ash. It is light demanding, frost hardy and shallow rooting and is better suited to deep fertile and well-drained soils with minimal exposure.

Cherry regenerates in the wild from seed and from suckering from parent trees. It grows rapidly on weed-free open sites to reach maturity in 55-65 years. Cherry sometimes dies for no apparent reason, followed by decay of the timber. Trees should therefore be kept vigorous by regular thinning carried out during the summer to minimise the chances of disease.