Amani Nature Reserve is a centre for biological diversity. The floristic composition is very diverse and there are 2012 vascular plants species per hector. Thus a large proposition of the endemic species is found within Amani Natural Reserve. The Reserve has been likened to the African equivalent of the Galápagos Islands in terms of their endemism and biodiversity. Therefore it is considered one of the most important forest blocks in Africa.
Approximately 3450 species of vascular plants recorded in the Usambara Mountains, over one quarter are likely to be endemic or near-endemic. In addition to the variety of plants, the mountains host a number of endemic or rare fauna species, including the Usambara eagle owl and a viviparous frog.