[willdough]

The linked article is about deforestation by humans and is irrelevant to the fact that huge parts of Spain have long been deserts.

[drabadur]

Deforestation is the only major relevant factor that led to the formation of any desert in Spain, and this started a "long" time ago, and is purely and simply controlled by humans. For example, the famous Tabernas desert is the result of deforestation, followed by intensive erosion.