Gabon has a land area of 26.8 million hectares and an estimated population in 2010 of 1.5 million people (United Nations Population Division 2010). It is ranked 103rd out of 182 countries in UNDP’s Human Development Index (UNDP 2009). The country is in the western part of the Congo Basin and is characterized by three biogeographic regions: a coastal sedimentary basin containing forest and savanna; a medium-altitude Precambrian plateau (averaging 600 m above sea level), which covers about two-thirds of the country and is largely forested apart from savanna in the east; and almost entirely forested granite massifs in the north and south – Cristal Mountains, Mayombe and Chaillu – where altitudes range between 800 m and 1000 m.