Technical Abstract: The soil microbial community is more diverse than any other group of organisms, The functions of these diverse communities range from nutrient cycling and residue decomposition, to soil structural component, to plant growth effects. Soil crusts provide a source of added carbon and nutrients in arid soils as well as protecting the soil from wind and water erosion. Management can have a large effect on microbial processes and community structure. While only a small portion of the microorganisms in soil can be collected and studied, new methods are available that will enhance our knowledge of what is happening underground. Community and process level studies, as well as investigations at the ecosystem and functional level, are needed to develop management systems that include soil biota for successful sustainable systems. Research is needed to increase our understanding of the diversity and function of microbial communities in ecosystems. Identification of functional genes and their use in diversity studies will assist in more meaningful assessments of soil health. Before soil microbial communities can be used as indicators we need to identify, for a given soil, the level of microbial diversity and community composition that withstands stress and maintains a quality ecosystem. Ecological investigations will enhance the understanding of microbial diversity and increase our knowledge of the functional roles of microbial communities in ecosystem health and productivity.