Microbe—Plant Interactions in Mediterranean-Type Habitats: Shifts in Fungal Symbiotic and Saprophytic Functioning in Response to Global Change

In any terrestrial ecosystem, the major allocation of carbon and the largest carbon sink is into components in soils responsible for the acquisition of nutrients and water. Although generally unappreciated, soil microbes are the dominant consumers of carbon. Mycorrhizal fungi are estimated to be the largest consumer group because of their large mass and direct access to the host carbon (Figure 14-1). Both these organisms and all others ultimately end up in decomposer mass, with most plant mass going directly to decomposers without passing through animals. Mediterranean-type habitats are semiarid regions that accumulate significant quantities of carbon below ground (e.g., Kummerow et al., 1978). Because of the arid conditions and the sclerophyllous nature of much of the plant tissue, decomposition tends to be very low. Therefore, the dynamics of microbes and their responses to change in the global environment are critical to predicting changes in ecosystem processes that will affect the regions of interest.