Herbivore-environment relationships in the Rwenzori National Park, Uganda

Abstract

The Rwenzori National Park lies astride the equator in the Western Rift Valley of Uganda. The Park contains a variety of plant communities, including forests, swamps and several kinds of grassland. The grasslands are noteworthy in that they support the highest recorded large mammal biomass of any natural area of the world (Bourlière, 1965; Coe, Cumming & Phillipson, 1976). An estimate of 294.9 kg ha⁻¹ for the average year-round standing-crop herbivore biomass is given by Field and Laws (1970). Interrelationships between the herbivore species, in particular, and their environment — vegetation, climate, soils and other animal species — have been studied by Field and Laws (1970). Herbivore distribution was found to show considerable heterogeneity in relation to the occurrence of different plant communities, the presence of standing water and the incidence of fire. Table 2 of Field and Laws’ (1970) paper gives estimates of the mean density km⁻² of nine herbivore species in ten sites or study areas. These data provided the starting point for the present investigation. Proceeding along different lines from Field and Laws, the data were analyzed in an attempt to clarify relationships within and between herbivores and study areas. Two methods were employed for the purpose — dual scaling and the contingency table analysis of E.J. Williams (1952). At a more fundamental level, the aims of the study were to illustrate the use of canonical analysis in an ecological context involving two categorial variables and to verify connections between dual scaling and contingency table analysis described in Sect. 5.5.1.