Research Letter #1


As a contribution to the workings of Council, I thought that I would attempt to present research news or commentary on matters of interest to members from time to time. The comments or opinions expressed are not necessarily those of my employer.

The words we use depend on who they are intended to reach but they also reflect our understanding of the subject matter. Words describe. In science, the ways we use words are most important and we try to be as precise as possible. Many of the terms used in fire ecology (and fire science) originated from encounters with fires in the field. These terms may vary from place to place and be general rather than precise. However, generating technical terms as replacements for common terms can raise many difficulties for the users of the scientist's information. Thus, technical words can become a barrier to communication, rather than an aid. It may be an impossible task to define all words precisely but, as we learn more, our language can become more precise yet not confined to specialists; effective communication is the aim.

We belong to the "Bush Fire Council" (not the "Bushfire" - one word - "Council"). What is a "bush fire" or "bushfire"? Is a "bush fire" a fire that burns bushes and only bushes? There is potential for confusion but the term "bush fire" probably comes from fires burning in the "bush", in the same way as we say we live in the "bush" capital. We use the term "bushfire" generally for fires spreading through "natural" fuels, including shrubs, that occur outside urban areas.

It has been interesting throughout the summer to hear how people refer to fires. The area burnt (not "destroyed"!) is a prominent reference point. The numbers of fire fighters attending a fire is another measure, eg. "One hundred fire fighters are at the fire front". Similarly, the numbers of fire fighting vehicles can be used as a way to describe the fire. Following one way of viewing the term "bush" fire, however, we might prefer to refer to the nature of the fuel in our talking about a fire.

Two main types of fuel produce quite different sorts of fires from the point of view of suppression and fire effects, even emission of greenhouse gases. They are the above- surface fires (usually called "surface" fires) and below-surface fires (usually called "peat", "ground" or "humus" fires). The below-surface fires are usually ignited by the above-surface fires.

We, in the A.C.T. are normally confronted with above-surface fires burning in litter, grass, shrubs or trees. Sometimes we see "crown fires". Can we have "crown fires" in shrubberies? It seems to me that describing an above-surface fire by the fuels that it burns is the most logical, as we have done for the main types of fires. Thus we could can have "litter" fires and "grass" fires. Fires that burn shrubberies often do so with the aid of burning litter or grass but we can call these "shrub" fires because shrubs are the least likely of these materials to burn; the other materials can be assumed to burn. Similarly, if the tree canopies burn (usually called a "crown" fire) we could, for consistency, call the fire a "tree-crown" fire because all the above-surface components of the forest contribute fuel. In using "tree" in "tree-crown", we avoid possible difficulties with the use of the word "crown".

I am sure that some people will say that what I have suggested is much the same as the normal practice for fire people. This may be so but what would you call a fire burning through grassy fuels on the forest floor? Is this a grass fire? If we follow the suggestions made above, it is a "grass fire" burning in a forest.

My aim here is not to suggest that the Council adopt a new title nor for Council to immediately adopt a new set of terms for fire fighters in the field. However, the names we use can lead to misunderstandings - especially internationally. May be there is more to a name than we think!

Malcolm Gill
Division of Plant Industry, CSIRO
29 January 1998