The Guardian ran a profile of William Simpson, a California activist who argues that wild horses can play a part in wildfire mitigation by reducing forests' flammable biomass through grazing. Link here.
Simpson argues that the steep decline of herbivores in the region – the deer population in California has shrunk to less than 500,000 from an estimated peak of about 2m in 1960 – is a factor in the state's overgrown forests and grasslands, which in turn feeds increasingly extreme wildfires.
"We've lost our herbivory so now we have abundant, abnormally high levels of vegetative materials – that is what's driving the fires," says Simpson.
Simpson has taken on the management of about 180 wild horses on and near his land, and is studying the effect that grazing has on managing grass and brush. His project is called the Wild Horse Fire Brigade.
In fact, two years ago, the Journal of Applied Ecology published a paper titled "Effects of large herbivores on fire regimes and wildfire mitigation." Its authors concluded:
[H]erbivores have the capacity to mitigate wildfire damage, and we provide guidance for grazing management for wildfire mitigation strategies. As areas undergoing land abandonment are particularly prone to wildfires, the maintenance or promotion of grazing by domestic or wild herbivores is a promising tool to reduce wildfire risk in a cost-effective way, while also providing other ecosystem services.