International Journal of Wildland Fire International Journal of Wildland Fire Society
Journal of the International Association of Wildland Fire

Using visual obstruction to estimate heathland fuel load and structure

G. M. Davies A B , A. Hamilton C , A. Smith B and C. J. Legg A D
+ Author Affiliations
- Author Affiliations

A Centre for the Study of Environmental Change and Sustainability, University of Edinburgh, Crew Building, King’s Buildings, West Mains Road, Edinburgh, EH9 3JN, United Kingdom.

B The Game and Wildlife Conservation Trust, Drumochter Lodge, Dalwhinnie, Inverness-shire, PH19 1AF, United Kingdom.

C Centre for Environmental History, University of Stirling, Stirling, FK9 4LA, United Kingdom.

D Corresponding author. Email:

International Journal of Wildland Fire 17(3) 380-389
Submitted: 6 February 2007  Accepted: 10 December 2007   Published: 23 June 2008


We present a simple non-destructive technique for assessing fuel load and critical aspects of vegetation structure that play important roles in determining fire behaviour. The method is tested in a Scottish Calluna vulgaris (L.) Hull heathland but could be applied to any vegetation up to ~1 m high. Visual obstruction of a banded measurement stick (the FuelRule) placed vertically through a stand of vegetation is governed by a combination of the height of the vegetation and its density. The vertical distribution of visual obstruction is calibrated to give estimates of total fuel loading, the loading of separate size categories and the vertical distribution and horizontal heterogeneity of fuels. The present paper provides a quick and simple method for estimating total aboveground biomass and structure that may be useful not just in studies of fire behaviour but where non-destructive assessment of biomass, vegetation density or canopy structure is needed. Calibration equations can be rapidly created for use in other vegetation or fuel types.

Additional keywords: biomass estimation, bulk density, Calluna vulgaris, canopy density, fine fuels, moorland, observer error, Scotland, shrub.


We thank the owners and gamekeepers of Ralia Enterprises for fieldwork access to Crubenmore, Ralia and South Drumochter Estates: Alistair and Michael Findlay, John and Ira Drysdale, Alistair Lyon and Ken Dakers, and the RSPB for access to the Abernethy Forest Reserve. Mark Hancock (RSPB), Michael Bruce and Gary Servant (Glen Tanar Estate) made helpful comments on the design of the FuelRule. Angus MacDonald of SNH gave extremely helpful comments on the manuscript. Three anonymous reviewers provided useful advice for which we are grateful. The present work was funded by NERC, The Game and Wildlife Conservation Trust and Scottish Natural Heritage.


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