The Nguu Mountains are a dissected range covering area of 1591 km2.[1] The highest elevation is 1550 meters.[2] The range lies in the watershed of the Wami River and its tributaries. The Nguru Mountains lie to the south, across an expanse of hilly country. The Maasai Steppe lies to the north and west.
The Nguru mountains intercept moisture-laden winds from the Indian Ocean, which provide most of the rainfall in the mountains. Most of the rainfall occurs in the November-to-May wet season, although mist and light rain occur at higher elevations during the dry season months. Rainfall is higher on the southern and eastern slopes, and lower in the mountains' rain shadow to the north and west. Temperatures are cooler and rainfall is higher at higher elevations.[3]
The Nguu Mountains, along with the others in the Eastern Arc, are made up of ancient crystalline Precambrian rocks that were uplifted over millions of years along fault lines. The most recent period of uplift started 30 million years ago, but the fault system and uplift process may be far older. Soils derived from these ancient rocks are not as fertile as the younger volcanic soils of mountains to the north and west.[4]
About thirty million years ago, the area was covered by extensive rainforest. During a cooler and drier period some ten million years ago, the lowland forests were converted to savanna, leaving the mountain ranges as "islands" where the tropical forests continued to flourish. The long-term persistence of a humid climate and the isolation of each mountain range has led to a great deal of endemism, and a very diverse flora and fauna.[5] The Nguu and other Eastern Arc mountains have extremely high biodiversity with numerous endemic species (more than 25 percent of the vertebrate species).[6]
The forests from 1000 to 1500 meters elevation are principally evergreen submontane forests, with characteristic Afromontane species. Newtonia buchananii is the dominant tree, with Albizia gummifera and other species.[11] An analysis of satellite images taken between 1999 and 2003 found 188 km2 of the mountains were still covered in evergreen forest.[12]
^N. D. Burgess et al. (2007). "The biological importance of the Eastern Arc Mountains of Tanzania and Kenya". Biological Conservation 134 (2007) pp. 209–231.
^Newmark, W. D., 2002, Conserving Biodiversity in East African Forests, a Study of the Eastern Arc Mountains. Ecological Studies 155. Springer-Verlag, Berlin, pp. 197
^N. D. Burgess et al. (2007). "The biological importance of the Eastern Arc Mountains of Tanzania and Kenya". Biological Conservation 134 (2007) pp. 209–231
^N. D. Burgess et al. (2007). "The biological importance of the Eastern Arc Mountains of Tanzania and Kenya". Biological Conservation 134 (2007) pp. 209–231
^N. D. Burgess et al. (2007). "The biological importance of the Eastern Arc Mountains of Tanzania and Kenya". Biological Conservation 134 (2007) pp. 209–231
^BirdLife International (2019) Important Bird Areas factsheet: Nguu Mountains. Downloaded from http://www.birdlife.org on 22/09/2019.