Katonga Wildlife Reserve - Frontier-publications.co.uk

Katonga Wildlife Reserve 22to maintain the Combretum sp., which are fire resistant (Buechner & Dawkins, 1961), in theface of Acacia gerradii, but caused sufficient seedling mortality to keep the woodedgrasslands open (5-25% tree cover (Langdale-Brown, 1960)). The effects of fire would havebeen compounded by the presence of high numbers of elephant, which would have causedsignificant mortality of adult trees (Buechner & Dawkins, 1961; Spence & Angus, 1971;Harrington & Ross, 1974; Pellew, 1983). Conditions of moderate grazing pressure andfrequent fire would have promoted valuable pasture species such as Themeda triandra andBrachiaria platynota which are highly palatable (Eggeling, 1941; van Oudtshoorn, 1992) butsusceptible to overgrazing (Edroma, 1981), and other fire resistant species such asHyparrhenia filipendula (Edroma, 1984).Through the 1970s and 80s grazing pressure in the reserve increased enormously, reducingthe fuel load available for grass fires during the dry season. This would have allowed someareas to escape burning long enough for woody plants, particularly Acacia sp. to establishthemselves, especially as the number of elephant declined dramatically through this period.Species typical of overgrazed areas such as Dichrostachys cinerea and Acacia hockii(Katende et al., 1995) would have invaded or increased in abundance, along with firesensitive grasses such as Brachiaria eminii and Panicum maximum (Harrington, 1974;Edroma, 1984) and Cymbopogon afronardus, which is distasteful to grazers (Eggeling, 1941),and thus flourishes in areas of heavy grazing as the more palatable species are preferentiallyconsumed.Cattle densities are now low by sustainable livestock production standards for the region(11ha per cow, using population estimates from Lamprey & Michelmore (1996), as opposedto 2ha per cow as recommended by the Department of Agriculture for the Ankole grazinglands, cited in Infield (1993)). This should allow for more frequent grass fires, and halt thewoodland and thicket regeneration and progression towards the climax types, but, with thecontinued low numbers of elephant, fire alone may not be enough to reverse the trend.Cymbopogon afronardus is difficult to get rid of as each clump must be dug out by hand(Infield, 1993), and so is likely to remain a feature of the reserve, as suggested by Langdale-Brown’s (1960) diagram of the relationships amongst vegetation types.2.5.2 DisturbancePatterns of human use and disturbance over time reflect the recent history of the reserve (seesection 1.3 for more information). Evidence of disturbance was found throughout the reserve,but particularly around Oburama in the north-west. This is similar to the distribution of bothhuts and cultivation reported in 1995 by Lamprey & Michelmore (1996) (Figs. 2.5 and 2.6).The large area under cultivation in the north-east of the reserve depicted in the ForestDepartment’s National Biomass Study land cover map (Fig. 2.3) could still be detected on theground, but had been largely abandoned following the repatriation of the Rwandan refugeesof the Kyaka I Refugee Settlement in 1994. There was no direct evidence of the 2,300 hutsdetected by Eltringham et al. (1992) in 1982 (Fig. 2.4), when the particularly high densities ofhuts to the west of the Kabega River reflected the different management of the two halves ofthe reserve.Frontier-Uganda Wildlife Protected Areas Project September 1997Baseline Surveys Programme Report No. 9