9 - Herbivory

Summary

African savannas are famous for the diversity and abundance of large mammalian herbivores that they support. However, over large parts of Africa the wild herbivores have been replaced by cattle, sheep and goats. Domestic livestock and wildlife form the basis of the present-day economic use of savannas, through meat production and tourism respectively. There has been considerable debate over the relative merits of ‘indigenous’ ungulates versus ‘introduced’ cattle (Dasmann 1964; Johnstone 1975; Walker 1979; Goodman 1985) in terms of economic return, protein production efficiency, ecological impact and disease tolerance. The Nylsvley programme included studies of both domestic and wild herbivores, often in comparative experiments.

The Nylsvley study also permitted comparisons to be made between mammalian and invertebrate herbivores, and within the invertebrates, between caterpillars and grasshoppers. Among the mammalian herbivores, the differences between predominantly grass-eaters (grazers) and predominantly tree-leaf eaters (browsers) are of scientific and commercial interest.

The work on herbivory performed at Nylsvley focused on two broad areas of interest. The first relates to secondary production in an infertile savanna system, and includes concepts such as forage consumption, carrying capacity, secondary production and conversion efficiency. These topics are addressed in this chapter. The second focus relates to plant–herbivore interactions, and is dealt with in Chapter 15. In brief, this chapter describes who eats what and how much, while Chapter 15 asks why.

Many people contributed to the research reported in this chapter.