Mariposa Monarca Biosphere Reserve

UNESCO Biosphere Reserve, inscribed 2006, in Mexico. The natural protected area belongs to the physiographic province of Eje Volcánico Transversal, which marks the extreme south of the Mexican Altiplain and separates it from the Balsas depression. It is a discontinuous mountain system, deeply dissected by strong tectonic processes, composed of a group of mountain ranges and hills that take up 77 per cent of the total surface, grouped in the south-centre portion, and separated by small intermountain valleys, 12 per cent, and plains, 6 per cent. It comprises five types of vegetation: sacred fir forests, characterised by the predominance of sacred fir (Abies religiosa), which constitute the characteristic habitat of the monarch butterfly (Danaus plexippus), pine–fir forests, pine forests, oak forests and cedar forests.