Thresholds Database > Society: collapse of society in the Puna de Atacama, Chile

Background

The area is located between the Salar de Atacama and the high elevation plateau, the Altiplano, between 3800 and 4000 metres altitude. The change from very arid to humid conditions began around 12,000 B.C. and lasted until 7,500 B.C. During this period, plant cover and diversity were high with the lake shorelines up to 70 metres above current levels.

Alternate Regimes

1. Glaciation, no human occupation (before 11,000 B.C.)

2. Humid environment, human occupation at elevations above 3,600 metres, lakes on high plains
- Early Holocene (11,000 - 7,500 B.C.)

- After 2,500 B.C.

3. Arid environment, human abandonment (Mid Holocene 7,500 - 2,500 B.C.)

Mechanism

This example demonstrates a shift in both the ecological system (climate, plant abundance and diversity) and the social system (human occupation). On this high altitude plateau, fluctuations in human occupation and abandonment correspond with changes in climate and lake levels. Periods of sparse flora and fauna and the lack of human occupation correspond to periods of glaciation (Regime 1) and aridity (Regime 3). More humid conditions (Regime 2) correspond with a productive lake system, abundant flora and fauna and human occupation. This example shows environmental thresholds that determine whether people can survive based on factors such as water availability and agricultural productivity.

Management Decisions in Each Regime