Ecological variation, institutional adaptation, and long-term social-ecological change: Lessons from the past

Background/Question/Methods

Societies frequently generate infrastructure and institutional
adaptations in order to mediate short-term environmental fluctuations.
However, the social and ecological consequences of activities directed
at dealing with short-term disturbances may, in fact, increase the
vulnerability of social-ecological systems to infrequent events or to
long-term change in patterns of higher frequency variability.
Understanding how the adaptation of economic, institutional, and
ecological systems to particular disturbance regimes may generate
fragilities requires the study of long-term change in social
ecological systems. The Hohokam, who occupied the Phoenix Basin for
over a thousand years and developed a complex irrigation society,
provide an excellent case study of such change. This paper presents a
simple bioeconomic model of Hohokam subsistence practices and explores
the relationship between key events in the Hohokam cultural sequence
and economic practices aimed at coping with environmental
fluctuations. The paper explores two key questions: how do decisions
about resource use strategies affect the capacity of the system to cope
with shocks?, and, based on reconstructed climate data, are there particular
frequencies of climatic shocks to which the system may have become
exceptionally vulnerable as it evolved over time?
Results/Conclusions
The analysis of the model illustrates how combining irrigated
agriculture with hunting and gathering can, as would be expected,
increase the robustness of the system to shocks in the wild resource
base (e.g. drought). However, the model illustrates the more subtle
trade-off between robustness to higher frequency, moderate-sized
shocks and lower frequency, larger shocks. Interestingly, combining
irrigated agriculture and hunting and gathering opens up the
possibility that both the wild and agricultural resource bases can be
severely degraded-something that is not possible for hunting and
gathering alone. Finally, by employing reconstructed climate data,
the model is used to show the importance of the temporal structure of
shocks in exceeding the capacity of the system to cope with
variation.