On the Origin of Structure by Means of Pedology.

Soil structure varies in form and degree of expression in different climatic regimes,  vegetation communities, geologic substrates, geomorphic surfaces, and disturbance regimes.  Soil structure can vary greatly with depth in mineral soils, and in many ecosystems is affected primarily by biological processes in near-surface horizons, shifting to physical processes in deeper horizons.  Careful examination of the variation in soil structure through space and time can provide insight to the origin of structure in different ecosystems.   This paper illustrates the variation of soil structure observed in the field across climatic, geological, and ecological gradients, and reviews key pedological studies on the origin of soil structure.  The goal of this paper to present some general hypotheses on the origin of soil structure that can facilitate future investigations on the function of soil structure in various ecosystems and disturbance scenarios.