Damage by non-native grey squirrels is a major risk to the health of woodland.
Grey squirrels have an appetite for stripping the bark of young trees, an act which can kill the trees outright or damage them enough to allow infections in.
A new report by some of England and Wales’s largest forestry organisations, estimates grey squirrels will cost the sector at least £1.1 billion over the next 40 years – in damaged timber, lost carbon revenue, and tree replacements.
Land managers report a trend to avoid planting broadleaved tree species that are most vulnerable to grey squirrel damage, including oak, beech and sycamore. They argue the risks of grey squirrel damage and cost of mitigation can be too high to justify against final timber values for trees which often take 80-100 years to mature. This shift could also have impacts for woodland biodiversity.
Woodland owners have named the grey squirrel as the number one threat to their broadleaf woods, and the organisations say previous calculations of the costs of squirrel damage (£6-10m per annum) are a huge underestimate.
The report, Analysis of the Costs of Grey Squirrel Damage, was commissioned by the Royal Forestry Society (RFS) in partnership with Forestry Commission, National Resources Wales, the National Forest Company and Woodland Trust. It developed a repeatable methodology for calculating grey squirrel damage by taking into account not just lost timber value but reduced carbon capture, as well as damage mitigation and the costs of trees to replace those have died as a result of grey squirrel bark stripping.
The results show a wide range of values depending on assumptions. The ‘probable scenario’ estimates that grey squirrels are costing a total of £37m a year to the sector in England and Wales. Even this does not include a range of more hard-to-measure impacts such as on landscape, public health or treasured wildlife caused by tree loss and damage.
Posted on: 21 January 2021