Supplementary material from "Crop booms as regime shifts"

A crop boom is a sudden, nonlinear, and intense expansion of a new crop. Despite their large impacts, boom-bust dynamics are not well-understood; booms are largely unpredictable and difficult to steer once they unfold. Based on the striking resemblances between land regime shifts and crop booms, we apply complex systems theory, highlighting the potential for regime shifts, to provide new insights about crop boom dynamics. We analyze qualitative and quantitative data of rubber and banana plantation expansion in two forest frontier regions of northern Laos. We show that preconditions, including previous booms, explain the occurrence (why) of booms, and triggers like policy and market changes explain their timing (when). Yet the most important features of booms, their intensity and nonlinearity (how), strongly depended on internal self-reinforcing feedbacks. We identify two types—built-in (neighborhood effects, imitation) and emergent (land rush) feedbacks—and show that they were social in nature, multi-scale from plot to region, and subject to thresholds. We suggest that these are regular features of booms and propose a definition and causal-mechanistic explanation of crop booms, examine the overlap between booms and regime shifts and the role of frontiers, and identify opportunities for management interventions before, during, and after booms.