Rwenzori Mountains - Flora and Fauna

Flora and Fauna

The Rwenzori are known for their vegetation, ranging from tropical rainforest through alpine meadows to snow; and for their animal population, including forest elephants, several primate species and many endemic birds. The range supports its own species and varieties of giant groundsel and giant lobelia and even has a six metre high heather covered in moss that lives on one of its peaks. Most of the range is now a World Heritage Site and is covered jointly by The Rwenzori Mountains National Park in Uganda and the Parc National des Virunga in Congo.

Although the flora in the Rwenzori is closely related to that of other East-African high mountains it is much more luxuriant here. This is mainly a result of the high and regular rainfall in the area. The distribution of vegetation is for a good deal determined by the altitude. At higher elevations, certain genera of plants grow unusually large. Most surprising are the giant heathers, senecios and lobelias, to which the Swedish botanist Olov Hedberg from the Uppsala University referred to as “botanical big game”. As the altitude increases, temperatures drop. The air also grows thinner, provoking intense radiation, even on clouded days. During the day the incoming radiation of ultraviolet and infrared light is fierce, while at night the outward radiation under a clear sky has a considerable cooling effect. The equatorial location dictates marked diurnal variations in temperature, whereas the seasonal differences are less important, as if it were summer every day, winter every night.

There is no water shortage in the Rwenzori. Yet several members of the afroalpine family bear resemblance with species that normally thrive in desert climates. The reason lies in their similar water economy. Although abundantly present, water is not always readily available to the afroalpine plants when they need it. The nightly frosts affect the sap transport in the plants, and the intake of water by its roots. As the day begins, the air temperature and radiation level rise rapidly, putting strenuous demands on the exposed parts of the plants. It is vital to meet the transpiration demands of the leaves, and maintain a proper water balance. To counter the effects of freezing, the afroalpine plants have developed the insulation systems which give them such a striking appearance. As a rule, these adaptive trends become more prominent as the altitude rises.

Vegetation zones

There are 5 different vegetation zones found in the Rwenzori Mountains. These are grassland (1000–2000m), montane forest (2000–3000m), bamboo/mimulopsis zone (2500–3500m), heather/Rapanea zone (3000–4000m) and the afro-alpine moorland zone (4000–4500m). At higher altitudes some plants reach an unusually large size, such as lobelia and groundsels. The vegetation in the Rwenzori Mountains is unique to equatorial alpine Africa.