Monday, August 6, 2007 - 4:00 PM

COS 7-8: Indicators of catastrophic regime shifts in ecological systems

Vishwesha Guttal and C. Jayaprakash. The Ohio State University

Instances of ecological systems undergoing catastrophic regime shifts have

been well documented. Such shifts may have serious ecological as well as

economic implications. An important problem in this context is to devise

indicators that can serve as warning signals of decreasing resilience and

hence, proximity to an impending transition. Some of the diagnostic measures

suggested include increase in the recovery time of the system (Ref: Held et

al., 2004, Geophysical Research Letters, Vol. 31, L232207) and an increase

in variance near a transition point (Carpenter et al, 2006, Ecology letters,

Vol. 9, 311-318). In this work, we suggest from studies of models that

asymmetry in the recovery time of the system and asymmetry in the time

series distribution can be used as warning signals for a catastrophic regime

shift. The limitations of various indicators and the conditions under which

they can be useful in real ecological systems will be discussed.