Every summer the Jewish National Fund sends a herd of around 500 sheep to the fields surrounding the Israeli city of Modi’in. The sheep help prevent fires by eating dried grass and thistles. They also lower the herbarium, giving smaller plant species the opportunity to develop and blossom.
http://www.modiinfo.com/newstop/item/5357-sheep-in-the-city-to-help-prevent-the-spread-of-fires