title: Prolonged instability prior to a regime shift.
abstract: Regime shifts are generally defined as the point of 'abrupt' change in the state of a system. However, a seemingly abrupt transition can be the product of a system reorganization that has been ongoing much longer than is evident in statistical analysis of a single component of the system. Using both univariate and multivariate statistical methods, we tested a long-term high-resolution paleoecological dataset with a known change in species assemblage for a regime shift. Analysis of this dataset with Fisher Information and multivariate time series modeling showed that there was a∼2000 year period of instability prior to the regime shift. This period of instability and the subsequent regime shift coincide with regional climate change, indicating that the system is undergoing extrinsic forcing. Paleoecological records offer a unique opportunity to test tools for the detection of thresholds and stable-states, and thus to examine the long-term stability of ecosystems over periods of multiple millennia.
authors.affiliation: Department of Earth and Atmospheric Sciences and School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America.
authors.forename: Trisha L
authors.initials: TL
authors.lastname: Spanbauer
authors.affiliation: U.S. Geological Survey, Nebraska Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America.
authors.forename: Craig R
authors.initials: CR
authors.lastname: Allen
authors.affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: David G
authors.initials: DG
authors.lastname: Angeler
authors.affiliation: Office of Research and Development, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio, United States of America.
authors.forename: Tarsha
authors.initials: T
authors.lastname: Eason
authors.affiliation: Department of Earth and Atmospheric Sciences and School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America.
authors.forename: Sherilyn C
authors.initials: SC
authors.lastname: Fritz
authors.affiliation: Office of Research and Development, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio, United States of America.
authors.forename: Ahjond S
authors.initials: AS
authors.lastname: Garmestani
authors.affiliation: Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.
authors.forename: Kirsty L
authors.initials: KL
authors.lastname: Nash
authors.affiliation: Department of Earth and Environmental Systems, Indiana State University, Terre Haute, Indiana, United States of America.
authors.forename: Jeffery R
authors.initials: JR
authors.lastname: Stone
mesh_terms: D057231:Climate Change; D017753:Ecosystem; D060106:Lakes