Organism interactions and soil processes

This chapter illustrates how the activities of soil biota, especially their trophic interactions, influence the processes of decomposition and nutrient cycling, and examines the significance of this for material flow and plant production in terrestrial ecosystems. The focus is on the availability of nitrogen and phosphorus since they are the two nutrients that most limit primary productivity in natural and managed terrestrial ecosystems. First, the issue of how soil microbes regulate the internal cycling of nutrients in terrestrial ecosystems is discussed. This is followed by a discussion of how soil animals influence nutrient cycling and plant growth through their feeding activities on microbes and other fauna.