‘Centres of diversity’ considers the Earth’s biodiversity hotspots and the benefits derived from this biodiversity. Conservation International has identified thirty-four ‘biodiversity hotspots’, twenty-five of which are wholly or partly in mountainous areas, particularly in the tropics. Tropical mountain forests are the most biodiverse ecosystems on Earth. The key factors for mountain biodiversity are the rich variety of habitats at all scales, both horizontal and vertical; species exploiting ecological niches as they emerge in mountain development; isolated species evolving in different ways; and the impact of human activities such as animal grazing and fire. Mountain areas are also centres of cultural diversity, and these are often closely related with biodiversity hotspots.