Abstract
Altitudinal changes in the vegetation of the Montane Forest Belt of Mt. Elgon, East Africa, were investigated by analysis of aerial photographs and by sample plots along two transects, one on a relatively wet, and the other on a relatively dry aspect.
Classifications for both tree and herb/shrub plots show that the forests along the two transects become increasingly similar floristically with altitude. The total number of tree species recorded is greater for the transect on the moister aspect. The mean altitudinal range for tree species increases on both transects with altitude, while that for herb/shrub species remains constant. It is suggested that the upper altitudinal limits of many species are determined principally by temperature-related factors, while the degree to which species extend their ranges downwards is much influenced by competition.
Structural heterogeneity is particularly well marked at altitudes corresponding to the bamboo zone on the wetter slopes and, even in the absence of bamboo, tree density here is much reduced. it is suggested that thicket-forming species, including bamboo, have enhanced competitive ability in intermediate altitude montane forests.
Previously advanced classificatory schemes for montane forest vegetation in eastern Africa are examined in the light of the findings.
Similar content being viewed by others
References
Agnew, A. D. Q., 1974. Upland Kenya wild flowers. Oxford University Press, 827 pp.
Atlas of Uganda, 1967. Department of Lands and Surveys, Uganda, 2nd ed. 81 pp.
Brock, P. W. G. & MacDonald, R., 1969. Geological environment of the Bukwa mammalian fossil locality. Eastern Uganda. Nature, Lond. 223: 593–596.
Chapman, J. D. & White, F., 1970. The evergreen forests of Malawi. Commonwealth Forestry Institute, University of Oxford. 190 pp.
Clifford, H. T. & Stephenson, W., 1975. An introduction to numerical classification. Academic Press, London & New York. 229 pp.
Coe, M. J., 1967. The ecology of the Alpine Zone of Mount Kenya. W. Junk, The Hague. 136 pp.
Coetzee, J. A., 1967. Pollen analytical studies in East and Southern Africa. Palaeoecology of Africa 3: 1–146.
Coetzee, J. A., 1978. Phytogeographical aspects of the chain of mountains on the castern side of Africa. pp. 482–494 in ‘Geoecological relations between the southern temperate zone and the tropical mountains’,.ed. C., Troll & W., Lauer. Erdwissenschaftliche Forschung, 11, Steiner, Wiesbaden.
Crawford, R. M. M., Wishart, D. & Campbell, R. M., 1970. A numerical analysis of high altitude serub vegetation in relation to soil erosion in the Eastern Cordiella of Peru. J. Ecol. 58: 173–191.
Dale, I. R., 1940. The forest types of Mount Elgon. Jl E. Africa Uganda nat. Hist. Soc. 9: 74–82.
Dale, I. R. & Greenway, P. J., 1961. Kenya trees and shrubs. Buchanan's Estates, Nairobi. 654 pp.
East African Meteorological Department, 1968a. Summary of rainfall in Uganda for the year 1967. Meteorological Dept., East African Community, Nairobi. 50 pp.
East African Meteorological Department, 1968b. Summary of rainfall in Kenya for the year 1967. Meteorological Dept., East African Community, Nairobi. 37 pp.
Ellenberg, H., 1979. Man's influence on tropical mountain ecosystems in South America. J. Ecol. 67: 401–416.
Grubb, P. J., 1974. Factors controlling the distribution of forest-types on tropical mountains: new facts and a new perspective. pp. 13–45 in ‘Altitudinal zonation in Malesia’, ed. J. R. Flenley. Dept. Geography, University of Hull.
Grubb, P. J., 1977. Control of forest growth and distribution on wet tropical mountains. Ann. Rev. Ecol. Syst. 8: 83–107.
Hamilton, A. C., 1972. The interpretation of pollen diagrams from highland Uganda. Palacoecology of Africa 7: 45–149.
Hamilton, A. C., 1975. A quantitative analysis of altitudinal zonation in Uganda forests. Vegetatio 30: 99–106.
Hamilton, A. C. & Perrott, R. A., 1978. Date of deglacierisation of Mount Elgon. Nature, Lond. 273: 49.
Hamilton, A. C. & Perrott, R. A., 1979. Aspects of the glaciation of Mt. Elgon, East Africa. Palacoecology of Africa 11: 153–161.
Hedberg, O., 1951. Vegetation belts of the East African mountains. Svensk Bot. Tidskr. 45: 140–202.
Hedberg, O., 1964. Features of Afroalpine plant ecology. Acta Phytogeogr. Suec. 49: 1–144.
Langdale-Brown, I., Osmaston, H. A. & Wilson, J. G., 1964. The vegetation of Uganda. The Government Printer, Entebbe. 159 pp.
Lind, E. M. & Morrison, M. E. S., 1974. East African vegetation. Longman, London, 257 pp.
Mabberley, A., 1973, Evolution in the Giant Groundsels. Kew Bull. 28: 61–96.
Moreau, R. E., 1966. The bird faunas of Africa and its islands. Academic Press, London & New York. 424 pp.
Morrison, M. E. S., 1968. Vegetation and climate in the uplands of south-western Uganda during the later Pleistocene period, I. Muchoya Swamp, Kigezi District. J. Ecol. 56: 363–384.
Morrison, M. E. S. & Hamilton, A. C., 1974. Vegetation and climate in the uplands of south-western Uganda during the later Pleistocene period, 2. Forest clearance and other vegetational changes in the Rukiga Highlands during the past 8 000 years. J. Ecol. 62: 1–31.
Mucller-Dombois, D. & Ellenberg, H., 1974. Aims and methods of vegetation ecology. Wiley, New York. 547 pp.
Peet, R. K., 1974. The measurement of species diversity. Ann. Rev. Ecol. Syst. 5: 285–307.
Pennington, T. D. & Styles, B. T., 1975. A generic monograph of the Mcllaceae. Blumea 22: 410–540.
Richards, P. W., 1964. The tropical rain forest. The University Press, Cambridge. 450 pp.
Riley, D. H., 1976. Magilligan Dunes, County Londonderry: classification of the vegetation. D. Phil. thesis. New University of Ulster.
Smith, J. M. B., 1977. Vegetation and microclimate of east-and west-facing slopes in the grassland of Mt. Wilhelm, Papus New Guinea. J. Ecol. 65: 39–53.
Sokal, R. R. & Sneath, P. H. A., 1963. Principles of numerical taxonomy. Freeman, San Francisco & London 350 pp.
Synnott, T. J., 1968. Working plan for Mount Elgon Central Forest Reserve. Forest Department, Uganda. 54 pp.
Tweedie, E. M., 1965. Foriodic flowering of some Acanthaceae on Mt. Elgon. Jl E. Africa nat. Hist. Soc. 25: 92–94.
van, Zinderen Bakker, E. M., 1962. A late-glacial and postglacial climatic correlation between East Africa and Europe. Nature, Lond. 194: 201–203.
Weatherby, J. M., 1962. Inter-tribal warfare on Mount Elgon in the 19th and 20th centuries. Uganda J. 26: 200–212.
Williams, W. T., Clifford, H. T. & Lance, E. N. 1971. Groupsize dependence: a rationale for choice between numerical classifications. Computer J. 14: 157–162.
Author information
Authors and Affiliations
Additional information
Nomenclature follows Agnew (1974) and Dale & Greenway (1961) with minor modifications after Chapman & White (1970), Mabberley (1973) and Pennington & Styles (1975).
The work was funded by a grant from the Natural Environment Research Council (U.K.). We are grateful to the Government of Kenya and to the Forest Department, Kenya, for permission to work on Mt. Elgon. Dr. A. D. Q. Agnew and Miss C. Kabuye very kindly identified some of the plant specimens. The illustrations were drawn by Mr. J. Shaw and the manuseript was critically read by Dr. D. Riley.
Rights and permissions
About this article
Cite this article
Hamilton, A.C., Perrott, R.A. A study of altitudinal zonation in the montane forest belt of Mt. Elgon, Kenya/Uganda. Vegetatio 45, 107–125 (1981). https://doi.org/10.1007/BF00119220
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00119220