In this video from BBC News, a French council has an inexpensive and environmentally friendly solution for managing overgrown lots on abandoned land: Soay sheep. The sheep's incredible appetite offer a natural alternative to costly and harmful alternatives like chemical weed killers or large machinery.
According to BBC News, the endangered animal is a descendant of early domesticated sheep, though much smaller than modern common breeds. Farmers had all but given up on the Soay for a variety of reasons -- they aren't good producers of wool or mutton, and are difficult for herders to manage.
Fortunately, the sheep's ability to eat almost anything and go anywhere make it a perfect candidate for clearing disused urban land that has been reclaimed by nature, and is giving the species a new valuable function in French cities.