Short-rotation forestry, by which fast-growing trees are cultivated and harvested between eight and 20 years after planting, appears to have potential as a source of renewable fuel for heat and power generation in Great Britain, according to a study undertaken for the Forestry Commission and Defra.

However, the study authors advise that a number of issues need to be addressed before short-rotation forestry could be widely established.

The two departments commissioned the review of possible environmental impacts of short-rotation forestry (SRF) as part of ongoing investigations and development of the wider mix of contributions that forestry can make to climate change mitigation and sustainable energy production. This mix includes energy crops, sawmill residues, and wood from existing forest and woodland.

Interest in SRF has been growing as part of the drive to develop renewable, carbon-lean alternatives to non-renewable fossil fuels such as oil, gas and coal. The build-up in the atmosphere of greenhouses gases, such as carbon dioxide, as a result of humans burning non-renewable fossil fuels is widely accepted as contributing to climate change.

The study looked at the potential impacts of SRF on biodiversity, soils, hydrology, pests and diseases, archaeology and the landscape. The study, the report of which which has been published on the Forestry Commission website, looked at 10 species of trees: four native species - alder, ash, birch and poplar; one naturalised species - sycamore; and five non-native species - three of Eucalyptus and two of southern beech.

Among the issues that the authors recommend should be examined further were:

• impacts on biodiversity, archaeology and the landscape. They recommend that clear guidance should be provided through a code of practice on how growers could establish and manage their SRF crops in ways that would minimise the effects on these aspects; and
• the high water use by some species, particularly eucalypts, which in certain parts of Britain could threaten water supplies. Further research is recommended to develop clear guidance for potential growers and land-use authorities on the areas where SRF would and would not be acceptable.

The study concludes,

“Overall, SRF appears to have potential ... as a source of renewable fuel. There are potential negative impacts from SRF, but these may be controlled and minimised by application of a creative, integrated code of practice to ensure that SRF operates in an optimal way to secure the positive impacts.”

The report recommends further research on three main areas: the growth rates and yields that might be achieved in Britain from SRF; the economics of SRF, particularly for the grower; and the water use of SRF stands.

The Forestry Commission's environment and operations advisor, Dr Helen McKay, said the report was a valuable contribution towards the possible development of SRF as part of a wood-fuel industry in Britain, adding,

"Because wood is a renewable, clean, carbon-lean fuel, short-rotation forestry could have a valuable role to play in Britain's contribution to climate change mitigation as part of a wider wood-fuel industry. This report has, importantly, given us a better insight into the potential for SRF, and has clear advice on further research.

“We will carefully consider all the recommendations and put in hand some of the research and development work. We recognise that there are potential problems as well as gains from expanding this type of woodland, and the report confirms this. Forestry operates within a well developed regulatory framework that includes safeguards to protect the environment and landscape, and the report shows where we have to do some work to make sure that SRF fits into this.”

The report can be downloaded from the Forestry Commission website at

http://www.forestry.gov.uk/pdf/SRFFinalreport27Feb.pdf/$FILE/SRFFinalreport27Feb.pdf .

NOTES TO EDITOR:

1. Short-rotation forestry is the practice of cultivating fast-growing trees that reach their economically optimum size between eight and 20 years old. Conventional forestry rotations in Britain vary between 40 and 150 years, depending on species. When felled, SRF trees are replaced by new planting or, more usually, allowed to regenerate from the stumps as coppice. It is a very old system of woodland management that has received recent attention because of the potential new market for its products.
2. Short-rotation coppice (SRC) uses even faster-growing tree species such as willows and poplars that, after harvesting, are not replanted, but sprout multiple new shoots from the stumps that grow on to form the next crop in as little as three years. It is also long-established, having provided “ withies” for uses such as basket making for a very long time.
3. Sustainably grown “biomass” fuels such as wood make only very small contributions to atmospheric carbon. The same amount of carbon that is released into the atmosphere when one crop is burned is reabsorbed by the plants grown for the next crop, and the carbon emitted by the machinery used to establish, grow, harvest and transport the biomass is very small. Where they replace fossil fuels, biomass fuels result in fossil fuel emissions to the atmosphere being avoided.
4. The eucalyptus species studied were Eucalyptus gunnii, E. gunnii x dalrympleana, and E. nitens . Eucalypts are a genus of trees that occur naturally mostly in the Southern Hemisphere, notably in Australia, where they are commonly known as "gum trees”. Eucalypts have been planted as ornamental trees in Britain for more than 150 years.
5. The southern beech species studied were Nothofogus nervosa (= procera ), or rauli beech, and N. obliqua , or roble beech, which have been grown in Britain on an experimental scale for many years. Southern beech is a genus whose natural range is also mostly in the Southern Hemisphere; these two species come from South America.
6. Besides short-rotation crops, forestry has the potential to provide wood fuel through traditional management practices. Sources already include small-diameter logs from forest thinning operations, the off-cuts from logs at sawmills, and the branches that are removed from harvested trees when they are being converted into logs for other uses.
7. Wood fuel, whether grown in SRF or SRC plantations or derived from traditionally managed woodland, could be used in different ways: in heating systems, electricity-generating plants or combined heat-and-power generating systems. Wood fuel is particularly suited to medium-sized buildings or groups of buildings that need a constant source of heat, such as schools, office blocks, factories, care homes, farms and hotels.
8. The study was undertaken and the report prepared by resource management consultants LTS International of Edinburgh.
9. Defra is the UK Government's Department of Environment, Food & Rural Affairs for England. It leads on the environment, food and rural affairs on behalf of all four countries of the UK in international affairs, and on UK-level matters affecting all four countries.
10. The Forestry Commission is the government department for forestry in Great Britain. Forest Research is the Commission's agency that conducts scientific research and technical development relevant to forestry. For further information, visit www.forestry.gov.uk and www.forestresearch.gov.uk .

NEWS MEDIA CONTACT: Charlton Clark, Forestry Commission press office, 0131 314 6500; mobile: 07810 181067