The ecology of the Kafue lechwe: the food supply.
Abstract
Changes in floristic composition were studied in 9 plant stands in the area utilized by lechwe (Kobus leche kafuensis) in Lochinvar National Park, Zambia. Perennial grasses tend to decrease under excessive grazing, often combined with insufficient rainfall or flood water, whilst annual grasses and dicotyledons increase. Climatic and hydrological differences between 3 yr appeared to exert a strong influence over the representation of the different spp. and, in some stands, may have masked differences due to grazing. The soil compaction was less in areas protected from grazing in one of the floodplain grassland stands, but no differences were detected in the other stands. The monthly variations in standing crop, amount of herbage produced and the amount removed were assessed in each of the 9 plant stands. The floodplain grassland stands were utilized by lechwe as soon as they became accessible, during the latter half of the dry season; they produced comparatively large amounts of herbage which were removed until they became flooded again. Proportionally more leaves were removed than the stems. The water-meadow grasslands were an important source of lechwe food during the rains and the beginning of the dry season. Again leaves were removed in preference to stems. The amounts removed from the termitaria stands, when the standing crop was high, were always proportionally lower than from the water-meadow communities. The digestibility of the stems of Panicum repens, Oryza barthii, Paspalum orbiculare and Echinochloa colonum was greater than that of the leaves; the relatively high levels of Si in the leaves may be a contributory factor. The N content of grasses was generally low, though the grasses probably provide sufficient available digestible protein to satisfy the maintenance requirements of adult lechwe. Neither the P requirement of grasses nor of the animals appear to be met. K, Mg and Fe levels seem adequate for both plants and animals, whilst Zn may be limiting to both. The Mn and Ca requirements of the lechwe may not be met in some cases.