Species interactions

This chapter starts by examining a simple classification of interaction between just two species into +, 0, or -. This produces a 3x3 matrix which reduces to six possible interactions. Only three have been studied by ecologists in any detail. These three are the following; (+ -) interactions: this covers grazing, browsing, and parasitism as well as traditional predator-prey interactions. The question is asked, are these savannah systems top-down or bottom-up regulated? To what extent are interactions important in the migration of ungulates? This chapter also examines the idea of multiple stable states and cycles, using the ‘fire, elephants, and trees’ interaction; (- -) interactions: usually called interspecific competition. Do the herbivores compete for resources? How important is kleptoparasitism between the major carnivores and is it responsible for the demise of such species as wild dogs in some areas? What is the evidence for resource partitioning?; (+ +) interaction: traditionally called mutualism. The ant-acacia interaction and the browsing ungulates. Is the so-called grazing succession real? Vultures, carnivores and carrion. How important are these mutualisms in the dynamics of the savannah systems?