Between 1980 and 2004, there were approximately 380,000 fires in Spain. The majority of these were caused by people, whether unintentionally or not. As well as the tragic loss of life, there is considerable damage to the environment and property.
Using information from 6066 Spanish municipalities, the researchers combined socio-economic and political information with the 'ignition danger' index used by the Spanish Forest Service to determine which human factors increase the risk of wildfires. The study was partly conducted under the EU-funded SPREAD project1.
One of the benefits of the method used by the researchers was the ability to integrate physical risk factors, such as climate and vegetation (for example the probability of lightning strikes, the dryness of the vegetation) with historical data on the risk of human-related causes of wildfires, to derive the risk index. A number of key factors that affect the frequency and distribution of wildfires caused by humans were identified:
- The density of agricultural machinery.
- The density of agricultural plots as a measure of agricultural land fragmentation. This is because fires are used in land management to prepare land for ploughing, increasing the risk of wildfires.
- Managing livestock in a traditional manner, where pasture is regenerated by burning.
- The unemployment rate which might promote intentional fires.
- A sharp decline in rural populations between 1950 and 1991. The value of rural land decreased as land was abandoned, and material which could act as fuel for wildfires built up.
- Increased urbanised human presence near forest areas.
- Density of roads and density of railways, both of which are related to accidental or negligent fires.
- Increased agricultural holdings, which reduce the risk of forest fire through irrigation.
- Greater numbers of risky infrastructures such as waste dumps, mines, quarries and areas under construction close to forest areas.
- The percentage of municipal land in protected natural areas as conflicts can arise over conservation goals.
- Agricultural areas which became forest land between 1970-1990, and increased fire risk through the accumulation of combustible materials.
- Of these, fragmentation of the agricultural landscape, abandoning agricultural land and modern developments and more people living near forested areas have the greatest impact on the risk of a wildfire.
Only the increase in agricultural holdings reduced the risk of human-caused wildfires. Larger land holdings are associated with a greater use of irrigation and mechanised farming methods, as opposed to traditional farming methods. Similar trends are seen in other Mediterranean countries.