Wikipedia
A garde champêtre is the combination of a forest ranger, game warden and police officer in certain rural communes in France. Their job is to report to the local mayor.
Many of these officers carry firearms (they commonly face poachers, many of whom are themselves armed) and other weapons. Mayors decide which weapons to provide them with, but gardes champêtres can purchase, retain and carry a much wider range of weapons than the urban police (police municipale) are allowed.
Their uniforms are not regulated and are at the mayor's discretion; they are traditionally green. The only compulsory element of their dress is a metal plaque or cloth escutcheon bearing the words: "LA LOI" (the law), the name of the commune and that of the garde champêtre. They cannot legally wear the dress attributed to the police municipale (marine blue with a clear blue trimming).
They are not under the supervision of the Gendarmerie but under the mayor's, their employer.