While the importance of biodiversity in ecosystem function has been accepted for some time (Tilman & Downing 1994), only recently has the relative importance of the diversity of functional characteristics of the biota been recognised (Grime 1997). Studies of above ground diversity predominate in the literature (Loreau et a1 2001). Little is known of diversity in soil. Soil is more complex and biologically diverse than above ground ecosystems (Wardle & Giller 1997). Thus it might be argued that the loss of a small number of taxonomic groups from a complex substrate such as soil will have little impact because many different microbes would contribute to the functions of soil and therefore, many species would be functionally redundant. However, research has found that high biodiversity may be considerably more important in complex ecosystems, such as soil, than in simple systems (Grime 1997) especially when changes over time and space affect the system (Loreau et al. 2001). Soil is the location for mineral cycling, decomposition of organic materials, and flow of energy. Understanding the processes regulating these functions, and their affect on plant growth, justifies understanding the biological diversity housed in soil