A Compass for Nature? Entropy in Watershed Responses to Disturbances

For many years, scientists have used Shannon’s entropy as a measure of complexity. However, the most elemental behavior of Shannon’s entropy, as related to variability in ecosystem properties, have been completely overlooked. Here, we explore information theory as a conceptual framework to understand the complexity associated with watershed responses to disturbances. By measuring the entropy in ecosystem response signals, all the possible system trajectories are constrained to that that satisfies the maximum entropy requirement. This trajectory is the entropy curve, defined by Shannon in 1948. We have performed an entropy analysis of hydro-biogeochemical signal components (such as discharge, suspended sediments and POM), in two mountainous watersheds in western Oregon.  We found that that specific curve segments correspond to a particular set of watershed responses to climate and/or human-induced disturbances. Interpreting Shannon’s entropy as uncertainty in hydro-biogeochemical signals in particular, and in watershed processes in general, might have profound implications in understanding their responses to disturbances. The analysis of entropy allows the study of changes in variability as an ecosystem response. We consider that these approach provides fundamental insight about the behavior of complex systems.