Improving existing windthrow models for application to continuous cover silviculture

Clocaenog wind study Wind damage Wind damage


To produce a wind risk model that can be applied to any stand structure.


Existing work on the stability of forests has concentrated on the risk of wind damage to even-aged stands (Gardiner et al., 2008).  Little work has been done studying within-stand variability of risk, either of even-aged stands, or within stands with a complex structure such as those found under Continuous Cover Foresry (CCF) (Gardiner et al., 2005).

In order to understand the stability of forests being transformed and managed under CCF, there needs to be a change in emphasis from stand-level to tree-level risk (Cucchi et al., 2005).  A combination of experimental and theoretical work will be used to improve existing wind risk modelling for even-aged stands, and extend it to stands with a complex structure (Hale et al., 2010).

ForestGALES (Dunham et al., 2000; Gardiner et al., 2004) is a PC-based wind risk model that predicts the risk of wind damage to the average tree in an even-aged stand.  To enable the use of this model to be extended to stands with a complex structure it needs to be adapted to:

  • Improve some of the basic assumptions and relationships used within the model
  • Include the risk of damage to trees of different sizes within a stand.

These changes will first be incorporated into the 'Research version' of ForestGALES, which has been developed to enable users to change parameters within the model.

Current and future work areas

  • Provide advice, based on current knowledge, to forest managers on stability aspects of transformation to continuous cover including complex structures
  • Develop and test a methodology for calculating risk to individual trees
  • Incorporate this methodology into a new version of ForestGALES capable of working at single-tree level.

Main contact

Sophie Hale.

This is a joint project with the Tree stability and climate programme.


Cucchi, V., Meredieu, C., Stokes, A., de Coligny, F., Suárez, J. and Gardiner, B. (2005). Modelling the windthrow risk for simulated forest stands of maritime pine (Pinus pinaster Ait.). For. Ecol. Manage. 213, 184-196.

Dunham, R., Gardiner, B., Quine, C. and Suarez, J. (2000). ForestGALES - A PC-based wind risk model for British forests.  User Guide. Forestry Commission, Edinburgh.

Gardiner, B., Marshall, B.J., Achim, A., Belcher, R.E. and Wood, C.J. (2005). The stability of different silvicultural systems: a wind-tunnel investigation. Forestry 78, 5, 471-484.

Gardiner, B., Suarez, J., Achim, A., Hale, S. and Nicoll, B. (2004). ForestGALES 2 – A PC-based wind risk model for British forests (PDF-689K).  User Guide. Forestry Commission.

Gardiner, B.A., Byrne, K., Hale, S.E., Kamimura, K., Mitchell, S., Peltola, H. and Ruel, J.-C. (2008). A review of mechanistic modelling of wind damage risk to forests. Forestry 81, 3, 447-463.

Hale, S.E., Gardiner, B.A., Wellpott, A., Nicoll, B.C., and Achim, A. (2012). Wind loading of trees: influence of tree size and competition. Eur J For Res 131: 203-217.

What's of interest

ForestGALES brochure
PC-based decision support tool that enables forest managers to estimate the probability of wind damage to any conifer stand in Britain.

Further details about ForestGALES