Feb. 25, 2011 European forests are regularly attacked by fire with often disastrous environmental, economic and social consequences.The most common reaction has been to fight fires at all costs because the negative impacts have been the primary concern.But now, a new approach to territorial management and to fire prevention and fighting is indispensable if we are to sustainably attenuate the intensity and severity of fires in Europe.Cemagref participates in the European Fire Paradox project to improve our knowledge on fire, which is in fact both a friend and foe, and can be used to prevent and fight forest fires.
Humans have used fire for ages to manage vegetation and adapt nature to their purposes, for example by controlled burning. But when fire is no longer controlled, it often leads to human, economic and ecological catastrophes that harm environments and threaten species. "Fire is a bad master, but a good servant." This Finnish expression sums up our paradoxical relation with fire. The paradox lies in the fact that by hindering forest fires at all costs, the potential damage of the next fire increases over time because the accumulation of plant biomass represents an increase in fuel that can cause and feed fires. However, the "let it burn" policy implemented in the large forests of North America cannot be used in Europe due to the presence of many homes in wooded mountain areas.
Reinstating fire in its role
To permanently reduce the intensity and frequency of forest fires in Europe, e.g. the terrible fires in Spain, France and Portugal in 2003 (1), and attenuate their economic and social impact, a new approach to territorial and fire management is indispensable. The Fire Paradox project (2) addressed precisely this topic with scientists from Cemagref and their partners from a total of 16 European countries. The central concept of this unusual project is "learning to live with fire" through integrated management, i.e. gaining better knowledge on fire, how it starts and spreads, but also viewing it as a means to prevent and fight fires by reducing the available fuel.
Learning about fire and how it works
At Cemagref, scientists have characterised the biological mechanisms governing flammability and combustibility of trees and plants. That information is used to develop methods to describe in detail the various plant species (bushes or trees, with or without branches, needles or leaves, etc.) and to rank stands according to their flammability and combustibility. That work, carried out with INRA and MDTA, helped in developing VESTA, a software simulator for large-scale fires in the European and Mediterranean context. Based on a physical approach to fire, it enables forest managers, researchers, fire brigades and forestry trainers to predict how a fire will spread on the basis of the available information (topography, wind, stand combustibility, etc.).
Identifying zones at risk
In parallel, work has been carried out on human dwellings or infrastructure in close contact with forests or natural areas. Due to urbanisation, habitat-forest interfaces have grown considerably over the last decades, thus vastly enhancing the conditions conducive to more frequent fires caused by human activities. In addition, the presence of combustible vegetation between built areas increases the vulnerability of residential areas. The researchers have developed a method to assess and map fire risks in the interface zones using an overall risk indicator calculated on the basis of past fires (density of fire starts and of full-blown fires, surface areas burnt). Using spatial analysis and satellite-image processing, the method serves to identify the interfaces that, due to residential characteristics, surface areas occupied, vegetation characteristics (types of stands, density, continuity), etc., are exposed to a high risk of fire and to act accordingly. A methods guide (3) has been drafted on interface mapping in Mediterranean regions to put territorial authorities and forest managers in a better position to anticipate and prevent fires.
Climate change and greater urbanisation are factors that will increase the frequency and intensity of forest fires in southern Europe. Thanks to the Fire Paradox project, scientific knowledge and technical means are now available to attenuate the consequences of fire.
Using fire against fire
Controlled burning means starting and controlling a fire to reduce plant biomass and thus limit extension of an uncontrolled fire to treetops. This technique, the topic of a good-practices guide drafted for the Fire Paradox project, is now used in regions of Europe where it was never used before. This technique also reduces the quantities of CO2 released to the atmosphere in that it limits the risks of uncontrolled fires that are a major source of CO2.
Counter-fire tactics, already used in Portugal, consist of setting up a controlled fire in front of a forest fire. This technique requires excellent knowledge on fire characteristics and behaviour. The Fire Paradox project was a chance to carry out the first digital simulations of counter-fire tactics using a digital model for fire spreading, called FIRETEC, and to produce training tools for subsequent users (forest managers, fire-fighting personnel, etc.).
(1) In France, the 2003 fires killed ten people, damaged dozens of homes and burnt over 600 square kilometres of territory, spanning 15 departments in southern France.
(2) The research project was launched in 2006 as part of the Sixth European framework programme for research and technological development (FP6) and ended in 2010. A total of 36 partners from 16 countries were involved.
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