Searching for unifying principles in soil ecology

The field of soil ecology has relatively few fundamental unifying principles that can be used to explain and predict patterns and processes in belowground ecosystems. Here we propose that a first step towards developing a more comprehensive set of unifying principles in soil ecology is to identify and understand the characteristics shared by a wide range of soils, the common mechanisms driving soil biogeochemical processes, and the biogeochemical constraints imposed on soil biota regardless of soil type. Very often, soil ecologists focus on the differences between soils when, in fact, many soils share a common set of ecological mechanisms that govern biogeochemical processes. Here we explore evidence for the existence of unifying principles in soil ecology, highlighting some of the similarities in carbon dynamics and soil communities across widely different soil types and examining the various mechanisms that may drive these similarities. Given that soils are extremely complex environments that exhibit substantial spatial and temporal heterogeneity, defining overarching principles is, arguably, more challenging in soil ecology than in other disciplines. However, recent methodological advances hold great promise for testing and formulating unifying principles, particularly when such methods are used consistently, in concert with other interdisciplinary approaches, and across a range of sites. Soils are not identical, but they do exhibit consistent patterns and processes that, if explored more intensively, will affirm the existence of unifying principles in soil ecology. (C) 2009 Elsevier Ltd. All rights reserved.