There is increasing awareness among biologists that mutualistic interactions play a key role in natural communities. One of the best-known examples of a mutualistic interaction is the mycorrhizal symbiosis formed between soil fungi and the majority of plants. These symbioses are present in almost all terrestrial ecosystems and yet, until recently, their contributions to the functioning of those ecosystems have been poorly understood. This multi-authored book gives an overview of recent advances and breakthroughs. The contributions of all the major mycorrhizal types to plant population biology, multitrophic interactions, biological diversity, ecosystem functioning, global change and evolution are given. This volume shows that collaboration in the rhizosphere is essential for plants, microbes, plant communities and ecosystems. It has been written with ecologists in mind, giving them easy access to an understanding of how these important interactions could shape our ecosystems.