Biosphere Reserves are areas of terrestrial or coastal/marine ecosystems, or a combination of both, recognised as such at international level under UNESCO’s Man and the Biosphere (MAB) Programme. It normally applies to territories that are home to natural values in line with their cultural heritage and where the population freely expresses the will to implement a sustainable development model that respects these values.

There are currently two Biosphere Reserves in the west of the Iberian Peninsula: Sierras de Béjar y Francia and Monfragüe.