Twiglet: UK woodlands and forests

The social and environmental value of woodlands and forests in the UK is estimated to be in the region of £1bn, states a postnote from the UK Parliamentary Office of Science and Technology.

Once, most of the UK was covered in woodland but the cover was gradually depleted as the demand for timber, fuel and agriculture grew.

By the beginning of the 20th Century, woodlands made up about 5% of the mainland.

Following the sharp increase in demand for wood products during World War One, the government established the Forest Commission. Its aim was to build a strategic timber reserve.

This was achieved by a large scale planting programme, mainly involving non-native conifers, such as North America’s Sitka Spruce (Picea sitchensis). The plantations were established on marginal agricultural land.

Overall, the UK has quite a diverse wooded landscape; the majority of the native trees are broadleaves. The nation has three native conifers: Scots pine, yew and juniper.

Woodland is considered “semi-natural” if it is composed of locally native species. A small proportion of the remaining woodlands are considered “ancient”, because their origins can be traced back to before 1600AD.

In recent years, a growing awareness for the need to conserve certain habitats and biodiversity has led to a shift in management practices.

From the primary concern being the production of timber, the focus is now on “sustainable forest management”.

This aims to provide social and environmental goods while maintaining an economically viable forest, protecting it for future generations.

The forestry and timber industry is estimated to contribute £7.2bn a year to the UK economy.

It produces nine billion cubic metres of wood products annually, however this is still less that a fifth (18% in 2007) of the total wood products used in the UK each year.

Most wood in imported. The majority of the imports come from Europe, however a sizeable minority comes from further afield.

Campaigners have identified that some of this wood is harvested from old-growth tropical forests, resulting in the loss of valuable habitat and biodiversity.

Looking more detail at the environmental value of a woodland or forrest, a number of “ecosystem services” can be identified, including:

  • protecting soil from erosion
  • reducing flooding in some catchment areas by intercepting rainwater and reducing run-off in stormy weather
  • helping reclaim contaminated land
  • proving shelter, shade and cooling in urban areas, and wind shelters on farmland
  • conserving biodiversity (broadleaved woodlands contain more than twice the number of rare species, according to the UK BAP, than any other habitat
  • conifer plantations also have role to play in conserving rare species, because they offer protection to species like the red squirrel and the capercaille.

Looking at the role of the UK forest and woodland cover in carbon sequestration, it is probably safest to state that it does have a role to play in mitigating the impacts, but it can never replace a broad strategic effort to decarbonise the UK’s economy and activities.

The UK has adopted a number of international forestry agreements – it was a signatory of the Statement for Forest Principles at the Rio summit in 1992. It also agreed to the general declaration on the Protection of Forests in Europe, which was presented at the 1993 European Ministerial Conference in Helsinki, Finland.

These agreements basically enshrine sustainable forestry measures into a policy framework. Hard to believe, but the European Union has no direct jurisdiction over forestry policy. Instead it is formulated at a member state level.

But there are some EU legislation that has an influence on forestry matters. These include CAP, EU Habitats and Species Directive, Environmental Impact Assessments, and the Water Framework Directive.

Within the UK, forest policy has been devolved to the national administrations. Policy in Scotland and Wales is decided by the national Forestry Commissions on behalf of the national political executives.

Since the widespread adaption of conifer plantations in the UK, most are same-age stands, which are felled in large areas in one go.

This is considered to limit or damage the social and environmental value of the plantations and local habitat, so there are plans to consider alternative management techniques, including:

  • Continuous Cover Forestry – smaller areas are felled in one go, allowing the overall habitat to remain largely undisturbed, and also allowing a mixed-age stand to develop)
  • PAWS restoration – some conifer plantations were created on ancient broadleaved woodlands, so there is a growing commitment to restore “PAWS” (Plantation on Ancient Woodland Sites)

Even though there is increased protection measures for semi-natural and ancient woodlands (such as SSSIs etc), their wildlife could still be under threat as a result of human activities. Recent surveys show that many woodland species have declined dramatically since the 1970s. One theory for this worrying trend is because it is the result of changes in the structure of the woodlands, stemming from the lack of management.

Threats to the woodland and the species within them include:

  • increasing fragmentation: small patches of woodland, isolated by other land use changes, are more vulnerable to change and can support fewer species
  • decline in woodland management: over the past century, active management of woodlands for timber has declined. This has led to a reduction in open areas within woodlands, on which many species depend, contributing to a decrease in biodiversity.
  • Overgrazing: Increasing deer numbers (including four introduced species) are an issue across the UK. Deer are a part of the woodland ecosystem, but overgrazing affects tree seedlings, ground flora and other wildlife. In upland areas, sheep can also cause overgrazing.
  • Pollution (and other external influences): the threat from acid rain has decreased over the years as the result of tighter emission controls of coal-fired power stations. However, localised air pollution can still be a problem. Fertiliser and pesticide drift from adjacent farmland is an issue on woodland edges.
  • Invasive species: some non-native species (such as rhododendron and grey squirrels) pose threats to woodland ecosystems by damaging or out-competing native species.
  • impact from recreational users: trampling can have a locally significant impact on woodland ground flora. Disturbance by humans and dogs may also affect other wildlife, such as breeding birds.

The future of woodlands is ultimately at the mercy of climate change. Changes are already being observed within the woods in the UK, Oak buds are opening up to two weeks earlier than what they were in the 1950s, probably as a result of warming temperatures.

There is one school of thought that suggests that increased levels of CO2 in the atmosphere will lead to plants and trees increase the rate at which they convert the gas and nutrients, leading to an increased growth rate.

However, other factors need to be taken into account, such as changes to precipitation or water tables.

All projections and models have a degree of uncertainty within them, so there is not a clear picture of how the nation’s woodlands will look in the future. The only certainty is that they are not going to remain static and change is occurring.

Source: UK Parliamentary Office of Science and Technology (Post)

Date: 02/02/2009 (however the postnote was first published in 2007)

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