Ecological thresholds and regime shifts: approaches to identification. Trends Ecol Evol

Department of Biology, University of Oslo, P.O. Box 1066, Blindern, N0316 Oslo, Norway.
Trends in Ecology & Evolution (Impact Factor: 16.2). 11/2008; 24(1):49-57. DOI: 10.1016/j.tree.2008.07.014
Source: PubMed


There is an apparent gap between the prominence of present theoretical frameworks involving ecological thresholds and regime shifts, and the paucity of efforts to conduct simple tests and quantitative inferences on the actual appearance of such phenomena in ecological data. A wide range of statistical methods and analytical techniques are now available that render these questions tractable, some of them even dating back half a century. Yet, their application has been sparse and confined within a narrow subset of cases of ecological regime shifts. Our objective is to raise awareness on the range of techniques available, and to their principles and limitations, to promote a more operational approach to the identification of ecological thresholds and regime shifts.

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    • "The detrended Cd concentrations in Fig. 4 were calculated by subtracting the Pc2 scores of individual sediment slices to the long-term trend modeled by a linear regression equation and are expressed as standardized residuals. The Sequential Regime Shift Detection software (significance level = 0.1; Rodionov, 2004; Andersen et al., 2009) was used to detect discontinuities in the first principal component (Pc1) scores, signaling at the regime shifts in the concentrations of chemical elements. Sequential Regime Shift Detection identified three periods: "
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    ABSTRACT: The study of a Posidonia australis sedimentary archive has provided a record of changes in element concentrations (Al, Fe, Mn, Pb, Zn, Cr, Cd, Co, As, Cu, Ni and S) over the last 3000years in the Australian marine environment. Human-derived contamination in Oyster Harbor (SW Australia) started ~100years ago (AD ~1900) and exponentially increased until present. This appears to be related to European colonization of Australia and the subsequent impact of human activities, namely mining, coal and metal production, and extensive agriculture. Two contamination periods of different magnitude have been identified: Expansion period (EXP, AD ~1900-1970) and Establishment period (EST, AD ~1970 to present). Enrichments of chemical elements with respect to baseline concentrations (in samples older than ~115calyears BP) were found for all elements studied in both periods, except for Ni, As and S. The highest enrichment factors were obtained for the EST period (ranging from 1.3-fold increase in Cu to 7.2-fold in Zn concentrations) compared to the EXP period (1.1-fold increase for Cu and Cr to 2.4-fold increase for Pb). Zinc, Pb, Mn and Co concentrations during both periods were 2- to 7-fold higher than baseline levels. This study demonstrates the value of Posidonia mats as long-term archives of element concentrations and trends in coastal ecosystems. We also provide preliminary evidence on the potential for Posidonia meadows to act as significant long-term biogeochemical sinks of chemical elements.
    Science of The Total Environment 01/2016; 541:883-894. DOI:10.1016/j.scitotenv.2015.09.017 · 4.10 Impact Factor
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    • "(2) We also used the empirical fluctuation processes tested by the cumulative sums of scaled residuals (OLS-based CUSUM test). These methods have been successfully used for time series analysis of fire and ecological data (Andersen et al. 2009, Pausas and Fernández- Muñoz 2011, Loepfe et al. 2012 "
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