Mechanistic soil-landscape modelling as an approach to developing pedogenetic classifications

Pedologists classify soil individuals into groups in order to communicate with each other about the properties of the soil individuals. Ideally, the classification should be meaningful, and not arbitrary. Some argue that it should be based on the genetics or evolutionary history of soil, such that it predicts properties of newly discovered or poorly known soil individuals. Here we propose pedogenetic systematics, which is an attempt to understand the pedogenetic interrelationships, trying to interpret the way in which soil has diversified and changed over time. Pedogenctic systematics may be defined as the reconstruction of the pattern of events that have led to the distribution and diversity of soil. This paper presents a mechanistic model for soil formation which considers the weathering of the bedrock and soil distribution by erosion. Using this model, we simulated soil development in a landscape. The simulated soil genetic properties at different times were grouped into numerical soil classes. This allows us to follow the evolution of the soil classes with time. Starting with a single soil class (thin soil), soil individuals in the landscape develop into more complex and diversified soil classes. This paper presents our first attempt to build a soil phylogenetic tree which allows us to begin formalising the concept of pedogenctic systematics. (c) 2006 Elsevier B.V. All rights reserved.