The afroalpine plant communities of Mt. Kenya (Kenya)
Rehder, H.; Beck, E.; Kokwaro, J. O.
The plant communities of the alpine and nival zones of Mt. Kenya, i.e. the vegetation above timberline of the montane Hagenia-Hypericum rain forest was studied by quantitative analysis of the species composition of about 150 typical plots which cover some 100 species of flowering plants. The analyses were arranged to yield 16 plant communities which, in turn, could be comprehended in representative vegetation types. In the lower alpine zone (which is commonly known as moorland) and immediately adjacent to timberline, Ericaceous bush as well as pure tussock moorland vegetation were encountered, each of which, in accordance with soil moisture is dominating wide areas or was found to interdigitate closely with the other. The main plant community of this zone is the Philippia-Pure Moorland-Community. The upper region of the lower alpine zone is a domaine of the Dendrosenecio brassica-Moorland-Community which contains two conspicuous giant-rosette plants, namely Dendrosenecio brassica (cabbage groundsel) and Lobelia keniensis. The most important communities of the upper alpine zone is the Dendrosenecio brassica-Lobelia keniensis-Community as a representative of the upper wetland and the Lobelia telekii-Dendrosenecio keniodendron-Community, well-known as the Dendrosenecio woodland which generally covers the steeper part of the slopes of the valley walls. In contrast to the literature, this community was not subdivided with respect to its field layers because the latter were understood as to result from a cyclic sequence of Alchemilla argyrophylla and Festuca pilgeri, respectively, each of which is capable of producing more or less closed and monotonous field layers. The Festuca pilgeri-Alchemilla agryrophylla-Community was established as another important community of the upper alpine zone, representing the vegetation type 'Upper tussocks and dwarf shrubs' which is characteristic of the upper boundary of the alpine belt. In the nival zone the vegetation peters out and genuine plant communities are difficult to abstract. The most widespread one is dominated by the herbaceous Senecio keniophytum, Festuca abyssinica and Alchemilla argyrophylla. Solifluction rather than frost itself or deficiency of moisture appears as the most serious environmental factor limiting higher plant life in the nival zone of Mt. Kenya. The plant communities, by inspecting the whole area of respect, which is represented by the map 'Mt. Kenya, 1: 25000', were localized and a vegetation map (1: 25000) was drawn which is available from the Survey of Kenya, Nairobi, Kenya.