• Managing wind risk to forests in northern Europe

Managing wind risk to forests in northern Europe

The STORMRISK project

In January 2005, a catastrophic storm damaged 85 million cubic metres of timber across northern Europe – ten times the annual production of UK forests. The STORMRISK project, funded by the EU through the Interreg North Sea Programme, was established to gather knowledge of managing forest wind damage, and to make it accessible to forest owners, managers and planners.

The project is a partnership of forestry companies and research organisations from Sweden, the UK, Germany and Denmark. Forest Research was invited to participate because of its experience in modelling and mitigating the effects of wind on forest stands.

Using the ForestGALES wind risk model

A version of Forest Research’s successful ForestGALES wind risk model can now be applied in other countries bordering the North Sea. This system can be accessed via the internet and calculates risk to forest stands based on local wind data and user-provided stand characteristics. Outputs include critical wind speeds expected to overturn trees, and the likely return period of such wind speeds.

During 2007, ForestGALES was applied at the landscape scale for a STORMRISK case study in Glen Affric, Scotland, using data from the Forestry Commission’s sub-compartment database to predict current and future risk (Figure 1). This risk assessment has since been used in the local design planning process.

To improve calculations of wind risk to stands with an uneven structure, and to develop a method of assessing risk using remote sensing data, Glen Affric has also been scanned using air-borne LiDAR (light detection and ranging). This technique uses laser pulses that can ‘see’ through forest canopy (Figure 2).

Figure 1
Geographic information system (GIS) map of wind risk in Glen Affric (areas of highest risk are shown in red)
Figure 2
Three-dimensional view constructed from air-borne LiDAR data, showing a section of forest in Glen Affric

The resulting data were analysed to provide the tree dimensions required by ForestGALES. Development of this link between remote sensing data and ForestGALES provides a method for detailed assessment of wind risk in complex forest structures.

Impacts of a changing climate

Forest wind risk management must consider a changing climate. Predictions of climate change for northern Europe include an increased frequency of extreme wind events and increased rainfall. Together these are expected to increase the risk of windthrow over the next fifty years. Advice on management of forests for wind risk in a changing climate, based on experiences from each participating country in STORMRISK, as well as the latest developments in wind-risk modelling, is available in an online toolbox.