A German-US team of scientists has demonstrated how threshold values for wildfires exist and could help to set standards in order to improve predictions about how and when these fires can change. These findings put forward by EU-funded project PATRES may also help to reconsider fire fighting strategies.

Scientists from the Helmholtz Centre for Environmental Research (UFZ) in Germany and the University of Michigan in the United States have demonstrated how threshold values for wildfires exist. This conclusion will help science to understand how the mechanisms which shape these wildfires work in order to be able to make predictions on what will change in future.

The research is an outcome of the PATRES ('Pattern resilience') project, which received €1.2 million under the 'New and emerging science and technology' (NEST) Cross-cutting Activity of the EU's Sixth Framework Programme (FP6). The team used a minimal model of fire dynamics that describes fire spread as a 'stochastic birth-death process'. This fire spread is similar to that of an epidemic spread. Using this model, the researchers replicated multiple regional patterns in fire regimes, enabling them to classify different regions in terms of their proximity to a critical threshold.

They evaluated the time series for large fires from the Canadian Boreal Plains, which have moved from being a subcritical regime to a critical regime and suggests that large forest regions in Canada are on the cusp of rapid change. These areas may even surpass the threshold value due to climate change. Finally, the scientists say strategies for fighting wildfires in extensive parts of Canada must be reconsidered.