Natural history of Mount Kenya

The timberline forest is commonly in cloud

Mount Kenya has several distinct ecological zones, between the savanna surrounding the mountain to the nival zone by the glaciers. Each zone has a dominant species of vegetation. Many of the species found higher up the mountain are endemic, either to Mount Kenya or East Africa, and are highly specialised.

There are also differences within the zones, depending on the side of the mountain and aspect of the slope. The south-east is much wetter than the north, so species more dependent on moisture are able to grow. Some species, such as bamboo, are limited to certain aspects of the mountain because of the amount of moisture.

Zones

The climate of Mount Kenya changes considerably with altitude. Around the base of the mountain is fertile farmland. The tribes living around the mountain have cultivated this cool relatively moist area for centuries.

Mount Kenya is surrounded by forests. The vegetation in the forests depend on rainfall, and the species present differ greatly between the northern and southern slopes. As time has passed the trees on the edge of the forest have been logged and the farmland has encroached further up the fertile slopes of the mountain.

Above the forest is a belt of bamboo. This zone is almost continuous, but is restricted to samll isolate bunches in the north because of low rainfall. The bamboo is natural, and does not require forest disturbance. Tracks are common through the bamboo. Bamboo suppresses other vegetation, so it is uncommon to find trees or other plants here.

Above the bamboo is the timberline forest. The trees here are often smaller than the trees in the forests lower down the mountain. The forest here is more intact, because it is less accessible and better protected.

When the trees can no longer grow the vegetation changes into heathland and chaparral, at around 3,000 m (9,800 ft). Heathland is found in the wetter areas, on the west side of Mount Kenya, and is dominated by giant heathers. Chaparral is found in the drier areas and grasses are more common. and bush fires are still frequent.

As the altitude increases the temperature fluctuations become extreme and the air becomes thinner and drier. This region is known as the Afro-alpine zone. The environment here is very isolated, with the only similar area nearby being the Aberdares, which are 80 km (50 mi) away. Many of the species here are endemic, with adaptations to the cold and fluctuating temperatures. Typical plants here include giant groundsels (senecios) and giant lobelias.

The region where the glaciers have recently retreated from is nival zone. It is the area that plants have not yet been able to colonise.