Alsace is a region with a great diversity of natural environments characteristic of a continental climate. It is home to many mountains, hills, rieds (forests that grow over rivers or meadows liable to flooding), or cultivated plains. The French government has provided for the creation of green networks. The aim is to allow unhindered circulation of animals and plant species thanks to hedges and grass strips. Alsace initiated it in 2003 with an area of 370,658 acres (150,000 ha) in the plain.