Soil is a fundamental and critical, yet often overlooked, component of terrestrial ecosystems. It is an extremely complex environment, supporting levels of diversity far greater than any ecosystem above ground. Bringing together existing knowledge in the areas of soil biology and physics, this book explores the key characteristics of soil spatial architecture, including how it develops and the consequences this has for life underground. The effects of soil's physical and biological components on their interactions and functions are used to demonstrate their roles in ecosystem dynamics.