The role of mycorrhizal symbiosis has been usually related to its impact on the plant mineral nutrition and consequently on the development of the plant species. However, it has been demonstrated that this symbiotic process has a key role in ecosystem stability. Numerous recent studies have outlined the major role of mycorrhizal symbioses in ecosystem functioning and the necessity to manage this soil microbial component in order ensure the productivity of plant ecosystems and to maintain plant diversity. The main objectives of this book are to present recent results showing the expected benefits in managing the mycorrhizal symbiosis in order to ensure the conservation of endemic plant diversity and to rehabilitate degraded soils in Mediterranean areas.