Geology
The high number of endemic species in the Usambaras is not an accident. It follows from old rock, tectonic isolation and a climate that has stayed moist for a very long time.
Ancient crystalline rock
The Eastern Arc is carved from Precambrian metamorphic and crystalline basement, among the oldest rocks of East Africa.
Sky islands
Block-faulting lifted the range into steep, isolated massifs. Each became a forest island, and isolation is the classic driver of endemism.
An unbroken climate
Facing the Indian Ocean, the mountains have caught moist sea winds for millions of years. The forests are regarded as refugia through global ice ages.
What this means at Nilo
Nilo rises from the foothills to Nilo Peak at 1,506 m, the highest point of the East Usambaras. Rain falls in every month, 1,200 to 2,200 mm a year, and the reserve is the water catchment for more than 30,000 people in 17 villages. Slope, soil and cloud base shape where the forest belts lie and where clearing on the edge causes erosion. None of this has been measured at Nilo in recent years.
Field placement at Nilo Forest
Three to six months at the reserve boundary, own project, data for your thesis. Start possible now, rolling intake.