Why manage woodlands?
There are no wildwoods in Britain and every woodland has been influenced to some degree by centuries of exploitation. From the last glaciation onward people have cleared woodland to grow food, and harvest wood for building and heat. Our woodlands have been tamed and the wildlife associated with them adapted to these managed conditions, to the point where they have become largely dependent on manmade change (especially for ‘letting the light in’). If woodland management activities change, then we must expect the wildlife dependent on these practises to change too.
There has been a tendency to leave some broadleaved woodlands alone, or ‘non-intervention management’, partly because it was seen as non-economic to manage as a timber crop, but also because of a misguided intention to ‘help wildlife’. Meanwhile, “there is strong evidence from studies of plants, insects and birds that some of our best-loved woodland wildlife is in crisis”: woodland plant species richness has declined by 19%, woodland butterfly populations declined by 74% and birds 32%*.
In addition, in the last two decades alone, there have been 14 new diseases (including the devastating Chalara ash dieback that threatens up to 95% of our ash trees) and five new major pest outbreaks that threaten our woodlands. A sustainable approach to woodland management could substantially mitigate these threats.
Key aspects of management include:
Light: woodland plants, including trees, shrubs and ground flora, require sufficient light for germination, establishment, flowering and seed production. In turn, these plants are the food source for many woodland insects, animals and birds. Therefore, management of light ensures healthy ecosystems and biodiversity.
Age, size and shape: woodlands where trees are all the same age, size and shape offer a limited range of habitats and are likely to be less resilient than a well-managed woodland. Diversity of age, size and shape within a woodland can provide protection against extreme events (e.g. outbreak of a pest), openings in the canopy and along rides provide light, promoting biodiversity, while veteran trees can be managed sensitively by allowing them space to thrive.
Benefits to the environment:
Healthy woodland provides multiple environmental benefits. It cleans our air (on average one hectare of UK woodland stores around 5.4 tonnes of carbon dioxide) and can mitigate flooding since trees intercept or use water in many ways – depending on species and size. Woodlands are recognised as providing a wide range of important habitats for wildlife. Many of the species associated with these habitats are dependent on woodland condition. Active management—which may include preserving ancient trees and deadwood, or thinning to allow light to reach the woodland floor—is essential to conserve and enhance biodiversity.
Benefits to society
Links between human health and wellbeing, and access to the natural world, are well-known and continue to influence forestry policy. Examples include tackling obesity, social isolation and improving mental health. There are clear links between active management and the appeal of woodlands: from the opening up of large coniferous woodlands for recreation, to tourism linked to bluebell woodland visits in the Spring. Unmanaged woodlands can be dark places and unappealing to people, and sometimes unsafe (e.g. dangerous trees). Climate change is predicted to have a severe impact on future society. Our woodlands are likely to play an ever-more important role in sheltering us from the effects of climate change (e.g. controlling flood run-off in water catchments, and reducing urban heat island effects). To achieve this woodlands themselves need to be resilient to environmental change (e.g. climate, new pests and diseases). Active management of woodlands will ensure a wide range of species, genetic diversity and age structure; the main elements essential to ensure resilience.
* Wildlife & Countryside LINK statement: http://www.wcl.org.uk/docs/2009/Link_position_statement_Woodfuel_Strategy_03Jul09.pdf
The Sylva Foundation has produced a very helpful booklet ‘Why manage woodland and who benefits?’