The Ecology of the Kafue Lechwe: As Affected by the Kafue Gorge Hydroelectric Scheme

Abstract

(1) The average biomass of Kafue lechwe at Lochinvar National Park, Zambia, is 66 kg. (2) Inadequate food, poor quality or insufficient quantity, can be an important mortality factor in lechwe. (3) An estimate of the number of lechwe that termitaria, water-meadow and floodplain grassland stands could carry at different times of the year was obtained using grass leaf standing crop, percentage of digestible dry matter of each sample, area of each stand and 3100 J M.E./24 h as the maintenance requirement of an average lechwe. (4) Under natural conditions the flood regime exerted the major influence on the lechwe habitat. The time of flood, speed of flooding and withdrawal and the depth and duration are the main factors which determined the floristic combinations in the area. Large numbers of herbivores utilized the area due to the apparent extension of the wet season through clear water flooding followed by the continuous uncovering of nutritious herbage throughout the dry season. The lechwe sub-population appeared to be above the carrying capacity of the habitat during the first half of the dry season if the flood water remained high. The digestibility and protein content of the herbage were sufficient, but the quantity was limiting. Throughout the wet season, the amount of available herbage was sufficient, but at times low digestibility levels may have limited intake. During the latter half of the dry season the quality and quantity of the herbage were adequate. (5) With the completion of the Kafue Gorge dam, temporary utilization of extra water storage is expected to cause the main adverse effects at Lochinvar. During the most critical months for lechwe survival the situation will be exacerbated. (6) The Iteshiteshi regulation will reduce the extremes and duration of the flood water and alter the speed of flooding and withdrawal. It will effect the floristic combinations in the area and modify the continuous availability of nutritious herbage throughout the dry season. The outlook for the only population of the semi-aquatic antelope, the Kafue lechwe, is bleak.