The palm grove was planted in 1069, when the town was founded, to ensure its subsistence. For centuries, farmers irrigated their fields using sophisticated pipe systems that drew water from the water table. Year on year, the palm grove has shrunk to just 3 000 hectares, compared with 10 000 at the beginning of the 20th century. Since the early 2000s, the authorities have launched reforestation programmes, the effects of which remain limited.