Smoldering ground fire in pine forest during a fire experiment
Source: BAM
Forest fires have been occurring in Germany for decades, not just since the major fires of 2017 and 2022. In Lower Saxony, there were already major forest fires in 1975 and in the 1990s. The effects of such fires are devastating, as they not only destroy large amounts of forest and vegetation, but also cause smoke that can sometimes be detected up to 100 km away. Forest fires can also have an impact on forestry and tourism. In the last 30 years, forest fires in Germany have caused 1.76 million euros in damage per year over an area of around 776 hectares.
The smoke from vegetation fires leads to higher air pollution and can cause respiratory diseases. It is therefore of great importance to understand the causes and effects of forest fires and to take preventive measures to prevent or at least minimize such disasters. This includes basic research, knowledge about the origin and spread of fires and about smoke gases, which are necessary to develop recommendations.
In order to achieve this goal, the EU project TREEADS has developed a comprehensive methodology to experimentally examine forest and vegetation samples from Saxony-Anhalt and Brandenburg with the project partner Otto-von-Guericke University at the Institute for Apparatus and Environmental Technology. The methodology includes elemental analysis, thermogravimetric analysis (TGA), smoldering tests in a tube furnace test, evaluation of the organic content and analysis using a hot storage furnace. The findings on self-ignition behavior and the resulting smoke gases serve as the basis for the recommendations to be developed in the project for emergency services and decision-makers regarding forest fire detection, control and prevention.
In summary, it can be said that spontaneous combustion is possible for various types of forest soil as long as the organic content of the forest soil is high enough.
The determined self-ignition temperature can serve as a control value for post-extinguishing measures: if the current soil temperature is below the self-ignition temperature, it can be assumed that the risk of self-ignition and re-ignition of the fire is low. However, if the ground temperature is above this value, further extinguishing or cooling measures can be initiated to minimize the risk of forest fires.
Self-ignition of forest soil samples demonstrated through hot storage tests.
Piechnik K, Hofmann A, Klippel A.
Fire and Materials. 2024, Volume 48, Issue 4, 495-507.