Species Diversity of Browsing and Grazing Ungulates: Consequences for the Structure and Abundance of Secondary Production

Abstract

There are two fundamentally different ways to look on the way consumers use their resources. The first is that different species partition the resource in a particular manner, so that some species get a particular part and other species another part. In this view, the sum of the shares is equal to the total. The second way of looking at resource partitioning is shaped by thoughts about niche differentiation: species differ in their ability to extract particular resources from a continuum, and because they are different there is an additive effect if different species utilise an area together. Specialization leads to increased partitioning of resources which leads to a higher total offtake. We are interested in the question, then, whether increased species richness of vertebrates that make use of the vegetation—that is, ungulate grazers and browsers—leads to an increased offtake of the plant biomass in an area, and subsequently whether, if true, this translates into higher herbivore biomass and/or productivity.