On the lower and drier islands the vegetation, before human colonization, consisted of savanna or steppe vegetation, with the flattest inland portion supporting semi-desert plants. At higher altitudes, a form of arid shrubland was also present. These islands were covered with savanna on the plains and arid shrubland on the mountainsides, but after over 500 years of human habitation (after Portuguese colonisation) nearly all the original vegetation has been cleared in favour of widespread agriculture including the grazing of goats, sheep and cattle and the planting of imported crop species. There are some remaining patches of dry forest high on steep mountainside including a number of endemic plant species, but these are inaccessible and hard to study.