Ecohydrology and Biogeochemistry of the Rhizosphere in Forested Ecosystems

Abstract

The rhizosphere, defined as the narrow zone within the soil centered on the root–soil interface, has long been recognized as a hotspot for biogeochemical cycling within the soil (Richter et al. 2007). Life on earth is directly dependent upon processes occurring within the small volume of soil surrounding roots (Hinsinger et al. 2009), making the rhizosphere the epicenter of the critical zone, where soil weathering, biogeochemical cycling, and root uptake of water and nutrients take place. The physical dimensions of the rhizosphere should be considered in mechanistic rather than in absolute terms, as its width (measured as the distance outward from the center of the root) varies in scale from sub-micron to supra-centimeter depending on the process considered (Hinsinger et al. 2009). For most considerations related to ecohydrology and soil water dynamics, the width of concern for the rhizosphere is on the order of several (<5) centimeters.