Montane woodlands and savanna occur in three locations of Africa: Angola (Bie-Serra de Mocaba Escarpments), Nigeria (Jos Plateau) and Ethiopia (Eastern and Western Ethiopian mountain massifs). The escarpments of Angola lie between sea level and 1,000 m (3,281 ft) above sea level and the area is considered one of the most biologically diverse and rich regions of the world. The region is home to 14 endemic bird species, which are under conservation threat due to deforestation, fire and increased economic pursuits, such as mining and agriculture. The political reformation of the region after the devastating Angolan Civil War has been crucial to land changes. The Jos Plateau of Nigeria is primarily composed of shallow sandy soils overlaying granite parent material. Savanna woodland systems are believed to be the potential natural vegetation community, but only remnant areas restricted to slopes too steep for agriculture remain. A matrix of woodland, forest and shrubland depending on precipitation lie below the alpine levels that top the Ethiopian mountain massifs. This area has been heavily impacted by high population densities (100 to 400 people per square kilometer) and a growing need for timber and agricultural development.