direction); however, time and space both share the common characteristics of preferentiality (preference for different spatial locations and preference for different stable states through time) and thresholds (abrupt changes) that govern soil functions and soil evolution.
Lin admits that there are many unknowns in the workings of the soil system, but he argues that his three principles offer useful perspectives for modeling and predicting soil change and pedogenesis. They are certainly areas where the systems approach may provide new pedological insights that build upon the foundations laid by Dokuchaev, Jenny, Simonson, and the other giants of the discipline.
ACKNOWLEDGMENTS
I would like to thank Allen G. Hunt for inviting me to write this chapter and two anonymous reviewers for their helpful and encouraging comments. My doctoral thesis dealt with soil‐landscape systems, but my interests have shifted to other areas during my career, mainly to aspects of ecology and geomorphology, so revisiting the old soil literature (including my own!) and updating myself on the latest research has proved to be at once a nostalgic, educational, and rewarding adventure.
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