A Study in Altitudinal Zonation in South Kigezi and on Mounts Muhavura and Mgahinga, Uganda

Publisher Website
Google Scholar
Abstract
South Kigezi, in the southwest corner of Uganda, is a mountainous region mainly over 6000 ft. in altitude, with many ridges 7000 to 8000 ft., dominated in the extreme southwest by the 3 most easterly peaks of the Mufumbiro mountains (of volcanic origin). The soils are mainly derived from clay rocks of the argillite series and correspond to the red loams and immature red loams of Shantz and Marbut. The country is well watered by numerous rivers and lakes, the largest of the latter being Lake Bunyoni. The vegetation formations recognized are (1) East African mountain forest containing (a) the subtropical zone (6000 to 7500 ft.), characterised by the almost complete absence of palms, the wild date palm, Phoenix reclinata, reaching its lowest boundary whilst its upper limit is marked by the entrance of the hollow-stemmed bamboo (Arundinaria alpina), Hagenia abyssinica, and Hypericum lanceolatum. The climax of this zone is subtropical forest which is gradually being replaced by meadow and pasture lands owing to felling and burning. Pennisetum clandestinum Hochst. is one of the dominant and most nutritious fodder grasses in the moist meadow lands. (b) The temperate zone (7500 to 10,000 ft.) is distinguished by forests of Arundinaria alpina together with Erica arborea, Hagenia abyssinica, and temperate genera of grasses such as Bromus, Festuca, Calamagrostis, and Avenastrum. (2) The subalpine and alpine formation contains (a) the subalpine zone (10,000 to 12,000 ft.) which is marked by the cessation of the bamboos and large trees, the increasing number of Ericaceous shrubs such as Erica arborea and Philippia johnstonii, together with the appearance of the arborescent Senecio and Lobelia Community, the grasses Andropogon amethystinus, Festuca abyssinica, and Poa spp. with abundant ground mosses and Helichrysum spp. (b) The alpine zone (12,000 ft. to the region of ice and snow) has a groundwork of Alchemilla aberdarensis, Helichrysum newii, Luzula volkensii, Festuca abyssinica, Deschampsia ruwenzorensis, Anthoxanthum nivale, with numerous mosses, including Breutelia subgnaphalea and Stereodon cupressiformis, above which rise Senedo alticola, rarely exceeding 5 ft. high in this zone, while unidentified lichens encrust the exposed rocks.