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ForestGALES is a computer-based decision support system that assesses the risk of wind damage to conifer forests in Britain and compares the impacts of different silvicultural practices. ForestGALES is recommended for use at forest scales, rather than for individual stands, because of inherent variability in predictions.

How ForestGALES works

Calculating wind risk

ForestGALES calculates the probability of wind damage to a stand in two stages by looking at information from the trees and the site.

Using information from the trees:

  • species
  • height
  • diameter
  • age

and then the site:

  • soil type
  • rooting depth
  • spacing
  • thinning

ForestGALES then calculates the critical wind speed at which trees will be damaged, either by uprooting or stem breakage, and its likely return period based on stand location.

Detailed Aspect Method of Scoring (DAMS)

The probability of damaging winds occurring is then calculated using information on the wind climate throughout Britain as classified in the DAMS scoring system. DAMS is a modelled windiness score calculated from tatter flag observations, elevation, aspect, topographical exposure, valley shape and direction.
DAMS values can be:

  • Calculated for a specific location directly; or
  • Looked up from the DAMS scores for the whole of Britain.

DAMS scores are available to download

This information can be used to assist stand management decisions, for example felling age, silvicultural practice and cultivation.

Using ForestGALES

Throughout its development, ForestGALES was designed in consultation with representatives of both private and state forestry organisations and is designed to be easy to use and includes extensive on-line help.


Latest version ForestGALES

ForestGALES 2.5 is now available for download.

The current version is ForestGALES 2.5, which is the upgrade to ForestGALES 2.1 and replaces all previous versions of the ForestGALES software, incorporating research done since the last upgrade. The main changes are:

Damage is less likely to be predicted

Users’ experience indicated that ForestGALES 2.1 tended to predict more damage than was observed. A comparison with actual storm damage, and ongoing research into the science of wind risk in forests, has supported this. As a result, in ForestGALES 2.5 the estimated critical wind speeds for damage are higher, and stands are now predicted to be less at risk of damage.

Change to inputs

In ForestGALES 2.5, the effects of cultivation and drainage on anchorage have been combined and replaced by rooting depth. A Soil and Rooting Helper is provided to help users decide on the correct combination of soil and rooting for a given site.

Crown size calculations

The calculations of crown size within ForestGALES have been revised and are now based on a much larger data set than before. For most species this makes little difference. Crown size calculations are substantially improved for western hemlock, Douglas-fir and lodgepole pine.

Research capability

ForestGALES 2.5 has a Research mode which has added features that make ForestGALES more flexible for research users. Species-specific external parameter files make it easier to alter parameters such as crown relationships or anchorage coefficients. New species can also be added. Weibull parameters describing the wind regime can be entered directly rather than being calculated from DAMS. A wide range of outputs is now optionally saved to a file.


fgr – the ForestGALES R package

A version of the ForestGALES wind risk model is available for use by forestry and land-use change scientists and specialists, ecologists and meteorologists, in a format that is flexible and fully customisable. This is designed to meet the needs of users for application in any forested landscape, and to encourage international collaboration on forest wind risk research.

Since the release of ForestGALES version 2.5, the tree stability team at Forest Research have used the R programming language for all further model development. The model fgr, the ForestGALES R package, is the product of the latest research and development.

R is widely used in the forestry and land-use change research sectors in Britain and throughout the rest of the world. Many models and utilities are available as R packages, thus providing the opportunity for relatively straightforward integration between tools within a common platform. R packages can also be used as a plugin within the QGIS software, as we have done with fgr in the FOSPREF-Wind project.  

What’s new in fgr?

This latest version of ForestGALES, fgr, features a series of modifications and improvements from ForestGALES 2.5, and as such fgr represents the cutting edge of forest wind risk modelling.  Two sets of changes have been made:

  • Firstly, improvements have been made to the ‘roughness’ method which underpins calculations of wind loading in uniform forest stands.
  • Secondly, we have introduced the “’turning moment coefficient’ (TMC) method for calculating risk to individual trees in mixed forest stands.

These changes are described in more detail:

Stand-level calculations

fgr represents an improvement on the traditional stand-level approach used in previous ForestGALES releases.  Several scientific advances have been incorporated into the calculations of critical wind speed in uniform stands:

  • We use new equations for more precise calculation of stem volume, based on the work of Fonweban et al. (2012);
  • The calculations of the effects of wind gusts, upwind gaps, and newly formed (brown) edges have been improved;
  • We have revised the method of calculating the contribution of the mass of canopy to the critical bending moment of the tree;
  • We have improved how the distribution of drag across the forest canopy is represented;
  • We have added more species to the ForestGALES parameterisation, including alternative conifer species (jack pine, white spruce, black spruce, balsam fir, maritime pine, radiata pine) and some broadleaved species (beech, birch, oak, and Eucalyptus globulus).

Individual-tree calculations

The traditional roughness method of ForestGALES calculates vulnerability and risk of the average tree in a stand.  Based on the innovative work published in Hale et al. (2012) and Hale et al. (2015), fgr allows the calculation of individual-tree vulnerability, and the associated risk of wind damage, in stands of mixed-species and irregular structure. This allows easier and more confident risk and vulnerability assessments in complex stands. The effect of complex stand dynamics on wind risk can be accounted for with the TMC method if tree-level competition indices are available. While still in a developmental stage, provisional tests have shown that results are consistent with observed damage.

Where can I download fgr?

The first release of fgr can only be downloaded from the Forest Research website.

This on-line form will capture your contact details. Terms and conditions must be accepted.

Once the form is complete, an email with four attachments will be sent to the email provided in the form. All personal data are treated in compliance with GDPR regulations.

What’s in the package

Once the form has been submitted, you will receive an email with four attachments:

  1. The Windows binary fgr package in a compressed archive (in .zip format)
  2. The fgr package User Manual in a PDF file
  3. A PDF file containing a copy of the fgr package Licence terms
  4. A text file with simple instructions to install the fgr package within your R library.

The fgr package is built in a modular way, so that not only wrapper functions for the two methods (‘roughness’ and ‘TMC’) are available for standard use, but all the individual functions are also available for advanced users. The simulations are fully customisable: all species parameters can be changed (including mechanical properties of wood, wood density, etc.), parameter sets for new species can be added and stored, and the values of physical constants (e.g. air density, snow density amongst many others) can be changed and stored for future use.

Model outputs can be produced in a compact form that is suitable for most standard use and contains calculated vulnerabilities and risks of uprooting and stem breakage, or in an extended format reporting the outputs of all advanced calculations. Example datasets are provided to help users familiarise with the functionality of fgr. All functions and datasets are documented. Working in batch mode in fgr is easy, since it takes advantage of all standard R practices for vectorised functions.

The fgr manual is a PDF document that details and explains the functionalities of the package and provides extensive background to the numerous aspects of wind damage risk research that went into the creation of fgr. Worked examples based on the provided datasets are included in the manual to provide further assistance, together with an extensive bibliography.

DAMS scores: a measure of windiness for the UK

As a hybrid-mechanistic model, fgr is designed to be able to simulate most forestry conditions, anywhere in the world. The windiness of a site is typically described with the scale and shape parameters of a Weibull distribution of mean wind speeds, as per standard meteorological practice.

In the UK, information on the wind climate throughout Britain is classified in the DAMS scoring system. DAMS scores in raster format (as GeoTIFF) are available to download in a coordinate reference system (CRS) compatible with Ordnance Survey data (EPSG: 27700), or alternatively in a CRS compatible with Google Maps, OpenStreetMap, etc. (EPSG: 3857).

Assistance with fgr

For technical support and enquiries relating to fgr, please contact Forest Research at: forestgales.support@forestresearch.gov.uk


How to Access ForestGALES

ForestGales can be installed on your computer (installation version) or run directly from the internet (web-based version).

Download ForestGales

To download ForestGALES you need an access code. New users of ForestGALES will need to purchase an access code which costs £50 + VAT.

To purchase an access code, contact:

Forestry Commission Publications (CST)
Chetham House, Bird Hall Lane, Cheadle Heath, Cheshire, SK3 0Z3.

0161 495 4845
forestry@theapsgroup.com 

Current users of FG will be sent an access code. If you have not received your code, please contact ForestGALES support: forestgales.support@forestresearch.gov.uk

Download ForestGALES now with your access code

By downloading ForestGALES 2.5, you agree to the terms of our licence agreement.

Web-based ForestGALES

ForestGales is also available as software that you operate through your web browser. The web-based version calculates the probability of wind damage for a single stand.

The web-based version of ForestGales is free

If you encounter any problems during registration or whilst logging in, please email us at: forestgales.support@forestresearch.gov.uk

Contact

If you encounter any problems please email us at: forestgales.support@forestresearch.gov.uk


ForestGALES – FAQ

Does ForestGALES work with mixtures?

The current version of ForestGALES models the effect of the wind on stands that are assumed to consist of identical trees. It’s suggested that in mixtures that the risk of wind damage to each component is calculated separately, using the top height and mean diameter of the component, and the average spacing based on the whole crop (i.e. all components of the mixture). The risk to the stand as a whole can be considered to be the highest risk for any component, since if one species is damaged then the resulting gaps will increase the risk of damage to the remaining trees.

Does ForestGALES work outside Britain?

The mechanisms by which trees are damaged by the wind are similar throughout the world. However the relationships between diameter and crown size, the resistance of trees to overturning and the wind climate will differ from country to country.

The current version of ForestGALES was designed for British conditions, but it has been successfully adapted for use in New Zealand, south-west France, Denmark, Canada (Quebec and British Columbia), and Japan. ForestGALES 2.5 includes a research mode that allows input parameters and wind climate to be easily modified for other countries.

What does ForestGALES calculate?

ForestGALES calculates the probability of average trees being damaged within a stand. Damage to the average tree will, by implication, mean that the stand as a whole will be substantially damaged.

How does ForestGALES compare to the Windthrow Hazard Classification (WHC)?

ForestGALES estimates the chance (or probability) of windthrow or stem breakage, rather than stating a precise height at which damage will occur as in the WHC. Probabilistic predictions are more realistic than precise heights since the occurrence of damaging winds varies from year to year, which has a powerful influence on the occurrence and spread of damage. The risk of damage is dependent on the windiness of the site. In the WHC the measure of windiness is much coarser than is used in ForestGALES. This allows ForestGALES to discriminate several levels of risk for trees in similar WHC classes. A study of actual storm damage indicated that stands can be grown for longer than if they were managed using the WHC.


ForestGALES – Technical support

For technical support and enquiries relating to ForestGALES, please contact Forest Research at the following address or email forestgales.support@forestresearch.gov.uk

Bruce Nicoll

Forest Research, Northern Research Station, Roslin, Midlothian, EH25 9SY

Tel: 0300 067 5287
Fax: 0131 445 5124


More about Forest Gales

Conference-workshop confirms Forest Research’s leading role in international wind risk modelling – Forest Research

Interview: how ForestGALES is the essential tool for wind risk – Forest Research


ForestGALES further reading

Achim, A. and Nicoll, B.C. (2009). Modelling the anchorage of shallow-rooted trees. Forestry 82: 273–284.

Albrecht, A., Hanewinkel, M., Bauhus, J. and Kohnle, U. (2012). How does silviculture affect storm damage in forests of south-western Germany? Results from empirical modeling based on longterm observations. European Journal of Forest Research 131: 229–247.

Anon (2006). Forest mensuration: a handbook for practitioners. Forestry Commission

Belcher, S.E., Harman, I.N. and Finnigan, J.J. (2012). The Wind in the Willows: Flows in Forest Canopies in Complex Terrain. Annual Review of Fluid Mechanics 44: 479–504

Björheden, R. (2007). Possible effects of the Hurricane Gudrun on the regional Swedish forest energy supply. Biomass and Bioenergy 31: 617–622.

Blennow, K. and Olofsson, E. (2008). The probability of wind damage in forestry under a changed wind climate. Climatic Change 87: 347–360.

Blennow, K., Andersson, M., Bergh, J., Sallnäs, O. and Olofsson, E. (2010). Potential climate change impacts on the probability of wind damage in a south Swedish forest. Climatic Change 99:261–278.

Blennow, K., Persson, J., Wallin, A., Vareman, N. and Persson, E. (2014). Understanding risk in forest ecosystem services: implications for effective risk management, communication and planning. Forestry 87: 219–228.

Cook, N.J. (1985). The designer’s guide to wind loading of building structures. Part 1: Background, damage survey, wind data and structural classification. Butterworths, London pp 371.

Coutts, M.P. (1986). Components of tree stability in Sitka spruce on peaty gley soil. Forestry 59: 173-197.

Coutts, M. P. and Grace, J. (Eds). (1994). Wind and wind-related damage to trees. Cambridge University Press.

de Langre, E. (2008). Effects of wind on plants. Annual Review of Fluid Mechanics 40: 141–68

Dhote, J-F. (2005). Implication of forest diversity in resistance to strong winds. In: M. Scherer-Lorenzen, C. Korner, and E-D. Schulze (eds.) Forest Diversity and Function: Temperate and Boreal systems. Springer. Pp. 291–307.

Dobbertin, M. (2002). Influence of stand structure and site factors on wind damage comparing the storms Vivian and Lothar. Forest, Snow and Landscape Research 77:187–205

Drouineau S., Laroussinie O., Birot Y., Terrasson D., Formery T. and Roman-Amat B. (2001). Joint evaluation of storms, forests vulnerability and their restoration. EFI Discussion Paper 9. European Forest Institute. 39 p.

Edwards, P.N. and Christie, J.M. (1981). Yield models for Forest Management. Forestry Commission Booklet 48. Forestry Commission, Farnham.

Fraser, A. I. and Gardiner, J. B. H. (1967). Rooting and stability in Sitka spruce. Forestry Commission Bulletin. 40, HMSO, London.

Gardiner, B.A., Stacey, G.R., Belcher, R.E. and Wood, C.J. (1997). Field and wind-tunnel assessments of the implications of respacing and thinning on tree stability. Forestry 70: 233-252.

Gardiner, B., Peltola, H. and Kellomäki, S. (2000). Comparison of two models for predicting the critical wind speeds required to damage coniferous trees. Ecological Modelling 129: 1–23.

Gardiner, B.A. and Quine, C.P. (2000). Management of forests to reduce the risk of abiotic damage – a review with particular reference to the effects of strong winds. Forest Ecology and Management 135: 261–277.

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

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

Gardiner, B., Blennow, K., Carnus, J-M., Fleischer, M., Ingemarson, F., Landmann, G., Lindner, M., Marzano, M., Nicoll, B., Orazio, C., Peyron, J-L., Reviron, M-P., Schelhaas, M-J., Schuck, A., Spielmann, M. and Usbeck, T. (2010). Destructive storms in European forests: past and forthcoming impacts. Final report to DG Environment (07.0307/2009/SI2.540092/ETU/B.1).

Gardiner, B., Schuck, A., Schelhaas, M-J., Orazio, C., Blennow, K. and Nicoll, B. (eds). (2013). Living with Storm Damage to Forests: What Science Can Tell Us 3. European Forest Institute.

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. European Journal of Forest Research 131: 203-217.

Hale, S.E., Gardiner B., Peace, A., Nicoll, B., Taylor, P. and Pizzirani, S., 2015. Comparison and validation of three versions of a forest wind risk model. Environmental Modelling and Software 68, 27-41.

Hanewinkel, M., Hummel, S. and Albrecht, A. (2011). Assessing natural hazards in forestry for risk management: a review. European Journal of Forest Research 130: 329–351.

Jactel, H., Nicoll, B.C., Branco, M., Gonzalez-Olabarria, J.R., Grodzki, W., Långström, B., Moreira, F., Netherer, S., Orazio, C., Piou, D., Santos, H., Schelhaas, M.J., Tojic, K. and Vodde, F. (2009). The influences of forest stand management on biotic and abiotic risks of damage. Annals of Forest Science 66:71.

Kennedy, F. (2002). The identification of soils for forest management. Forestry Commission Field Guide

Lavers, G.M., (1969). The strength properties of timbers, For. Prod. Res. Lab. Bull. 50 (2nd edition), HMSO, London.

Levy, P.E., Hale, S.E. and Nicoll, B.C. (2004). Biomass expansion factors and root:shoot ratios for coniferous tree species in Great Britain. Forestry 77: 421-430.

Lindroth, A., Lagergren, F., Grelle, A., Klemedtsson, L., Langvall, O., Weslien, P. and Tuulik, J. (2009). Storms can cause Europe-wide reduction in forest carbon sink. Global Change Biology 15: 346–355.

Mason, W. L. and Quine, C. P. (1995). Silvicultural possibilities for increasing structural diversity in British spruce forests: the case of Kielder forest. Forest Ecology and Management 79:13–28.

Mason, W.L. (2002). Are irregular stands more windfirm? Forestry 75: 347–355.

Mayhead, G.J. (1973). Some drag coefficients for British forest tree derived from wind tunnel studies. Agricultural Meteorology 12: 123-130.

Miller, K. F. (1985). Windthrow Hazard Classification. Forestry Commission Leaflet 85, HMSO, London.

Neild, S.A. and Wood, C.J. (1999). Estimating stem and root-anchorage flexibility in trees. Tree Physiology 19: 141-151.

Nicoll, B.C. and Ray, D. (1996). Adaptive growth of tree root systems in response to wind action and site conditions. Tree Physiology 16: 891-898.

Nicoll, B.C., Gardiner, B.A., Rayner, B. and Peace, A.J. (2006). Anchorage of coniferous trees in relation to species, soil type and rooting depth. Canadian Journal of Forest Research 36: 1871-1883.

Nicoll, B.C., Gardiner, B.A. and Peace, A.J. (2008). Improvements in anchorage provided by the acclimation of forest trees to wind stress. Forestry 81: 389-398.

Peltola, H., Gardiner, B.A., Kellomäki, S., Kolström, T., Lässig, R., Moore, J. and Quine, C.P. and Ruel, J-C (Eds). (2000). Wind and other Abiotic Risks to Forests. Forest Ecology and Management, Special Issue.

Petty, J.A. and Swain, C. (1985). Factors influencing stem breakage of conifers in high winds. Forestry 58: 75-84.

Pukkala, T. and Kangas, J. (1996). A method for integrating risk and attitudes towards risk in forest planning. Forest Science 42:198–205.

Quine, C.P. (2000). Estimation of mean wind climate and probability of strong winds for wind risk assessment. Forestry 73: 247-258.

Quine, C.P. and Miller, K.F. (1991). Windthrow – a factor influencing the choice of silvicultural systems. In: Silvicultural Systems, Ed: P. Gordon, ICF, Edinburgh, pp 71-81.

Quine, C.P. and Gardiner, B.A. (1992). Incorporating the threat of windthrow into forest design plans. Research Information Note 220. Forestry Commission Research Division, Farnham.

Quine, C.P. and White, I.M.S. (1993). Revised windiness scores for the Windthrow Hazard Classification. Forestry Commission Research Information Note 230, FC, Edinburgh.

Quine, C.P., Coutts, M., Gardiner, B. and Pyatt, G. (1995). Forest and Wind: Management to Minimise Damage. Forestry Commission Bulletin 114, HMSO, London.

Quine, C.P. and Bell, P.D. (1998). Monitoring of windthrow occurrence and progression in spruce forests in Britain. Forestry 71: 87–97.

Quine, C.P. and Gardiner, B.A. (2007). Understanding how the interaction of wind and trees results in windthrow, stem breakage and canopy gap formation. In Johnson, E. and Miyanishi, K. (Eds) Plant disturbance ecology: the process and the response. Academic Press. 698p. Burlington, MA, USA.

Raupach, M.R. (1994). Simplified expressions for vegetation roughness length and zero-plane displacement as functions of canopy height and area index. Boundary-Layer Meteorology 71: 211-216.

Raupach, M.R., Finnigan, J.J., and Brunet, Y. (1996). Coherent eddies and turbulence in vegetation canopies: the mixing layer analogy. Boundary-Layer Meteorology 78: 351–382.

Ray, D., White, I.M.S. and Pyatt, D.G. (1992). The effect of ditches, slope and peat thickness on the water regime of a forested gley soil. Soil Use and Management 8: 105-111.

Ray, D. and Nicoll, B.C. (1998). The effect of soil water-table depth on root-plate development and stability of Sitka spruce. Forestry 71: 169-182.

Rudnicki, M., Mitchell, S.J. and Novak, M.D. (2004). Wind tunnel measurements of crown streamlining and drag relationships for three conifer species. Canadian Journal of Forest Research 34: 666-676.

Ruel, J.-C., Achim, A., Espinoza, R.H., Cloutier, A. and Brossier, B. (2010). Wood Degradation after Windthrow in a Northern Environment. Forest Products Journal 60: 200-206.

Savill, P.S. (1983). Silviculture in windy climates. Forestry Abstracts 44: 473-488.

Schelhaas, M.J., Nabuurs, G-J. and Schuck, A. (2003). Natural disturbances in the European forests in the 19th and 20th centuries. Global Change Biology 9: 1620–1633.

Schelhaas, M.-J., Hengeveld, G., Moriondo, M., Reinds, G.J., Kundzewicz, Z.W., Maat, H.t., and Bindi, M. (2010). Assessing risk and adaptation options to fires and windstorms in European forestry. Mitigation and Adaptation Strategies for Global Change 15: 681–701.

Seidl, R. and Blennow, K. (2012). Pervasive growth reduction in Norway spruce forests following wind disturbance. PLoS ONE 7:1–8. http://dx.plos.org/10.1371/journal.pone.0033301.

Somerville, A. (1980). Wind stability: forest layout and silviculture. New Zealand Journal of Forestry Science 10: 476-501.

Suárez, J.C., Gardiner, B.A. and Quine, C.P. (1999). A comparison of three methods for predicting wind speeds in complex forest terrain. Meteorological Applications 6: 1-14.

Telewski, F.W. and Beals, W.J. (1995). Wind induced physiological and developmental responses in trees. In: Wind and wind related damage to trees. (Ed) Coutts and Grace. Cambridge University Press, 485 pp

Thom, A.S. (1971). Momentum absorption by vegetation. Quarterly Journal of the Royal Meteteorological Society 97: 414-428.

Troen, I. and Petersen, E.L. (1989). European Wind Atlas. Risø National Laboratory, Denmark.

Usbeck, T., Wohlgemuth, T., Dobbertin, M., Pfister, C., Bürgi, A. and Rebetez, M. (2010). Increasing storm damage to forests in Switzerland from 1858 to 2007. Agricultural and Forest Meteorology 150: 47–55.

Valinger, E. and Fridman, J. (2011). Factors affecting the probability of windthrow at stand level as a result of Gudrun winter storm in southern Sweden. Forest Ecology and Management 262:398–403.

Vollsinger, S., Mitchell, S.J., Byrne, K.E., Novak, M.D. and Rudnicki, M. (2005). Wind tunnel measurements of crown streamlining and drag relationships for several hardwood species. Canadian Journal of Forest Research 35: 1238-1249.

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