There are reports that a mountain bike’s disc brake, which has overheated from a rapid descent, is enough to start a forest fire. The discarded wheel initially ignites dry grass on the ground, without suitable countermeasures the flames quickly spread to the undergrowth and can quickly cover the entire forest.
But what if there is no dry grass and little undergrowth? Thinning out the undergrowth is a tried and tested fire protection measure – and a task that in many regions of the world can confidently be left to herbivores such as sheep, goats or wild herbivores. This shows an overview in the trade journal Journal of Applied Ecology.
In particular, where the land was once cultivated by humans, large herbivores are effective fire brakes, according to the conclusion of the work. The overgrown areas gradually grow over with bushes and trees, and combustible material accumulates. This increases the risk of forest fires and leads to more intense fires. “Herbivores cannot completely prevent forest fires, but they can influence their frequency and intensity,” says Julia Rouet-Leduc, lead author of the study and doctoral candidate at the German Center for Integrative Biodiversity Research (iDiv) in Leipzig.
Do you graze intensively for a short time or permanently with fewer animals? The results are different
Many trees are not damaged if only the undergrowth burns away. However, if the fire gets too big, the tree tops also go up in flames, and the damage to the ecosystem quickly becomes considerable. This can be counteracted if an area is regularly grazed by herbivores, says Rouet-Leduc. The suitable animal species depend on the respective ecosystem. “In Turkey and Greece, for example, sheep and goats could do the job,” says Rouet-Leduc. These would be traditionally kept there anyway and could move quickly through the landscape in herds. It is also optimal to mix animal species with different preferences, those that decimate the ground vegetation with those that are interested in undergrowth, bushes and trees.
In their paper, the researchers differentiate between different ways of keeping the vegetation short with the help of animals. Short-term intensive grazing of an area could, for example, together with other protective measures, create firebreaks that slow down the spread of the fire because there is no combustible food there. Less intensive grazing can also have this effect, but does not lead to homogeneous and low vegetation. Fire protection and environmental protection could work together, says Rouet-Leduc. “At the same time, we have to accept that fires are natural processes that are important for many ecosystems. And we have to learn to live with them to a certain extent.”
Together with her colleagues, Rouet-Leduc evaluated various older studies that examined the relationships between herbivores, vegetation structure, fire risk, fire frequency and fire damage. The international team found out that herbivores can reduce the damage caused by forest fires. The researchers therefore recommend promoting grazing in areas “that are no longer in use due to land abandonment”. Overall, “fire prevention with animals” should be financially supported, writes the team. Letting animals do the work is a cost-effective way of managing land.