The methodological paper that we worked on during the Santa Fe Institute workshop last October became available few weeks ago. It presents a suite of most developed methods for identifying early-warnings and provides clear step-by-step examples on how to apply them, in an attempt to offer a protocol to the uninitiated into the field. Most of the content of the paper is presented in simple form- together with more supporting material- on the newly launched Early Warning Signals Toolbox. This website accompanies the paper and aims to be a source of existing methods, newly developed methods, and a repository of case studies. Have a look and if you are interested to contribute, don’t hesitate to contact me!
In a recent work with Tony Ives, we showed how modified linear models with time-varying parameters can be used to extract an indicator of instability for a time series that may be drifting towards a regime shift. The paper is available online in Ecosphere. The idea is simply that instead of fitting an autoregressive model and finding a fixed value for its parameters, to fit an autoregressive model with parameters that change based on the point one is along the time series. This is possible due to a Kalman filter fitting proceedure and seems to not require a too much long time series. We also show that fitting threshold autoregressive models can distinguish alternative attractors in a flickering time series. The code to execute all this is currently in Matlab, but we aim in converting it to an easy to use routine in the R environment.
The paper we were working on within the EUR-Oceans group for the Baltic Sea just appeared in PLoS One. We show for the first time how different methods for identifying regime shifts can be applied in the marine environment and how they can be interpreted. Hopefully this study will pave the way for same sort of applications in coastal and marine ecosystems.
Our paper with Jiangfeng Feng and Egbert van Nes in Theoretical Population Biology just appeared online http://dx.doi.org/10.1016/j.tpb.2012.06.003 . We show that predator interference has a dual effect on the dynamics of multispecies predator prey communities: on one hand it increases their dynamical stability (in the sense of leading to stable equilibrium dynamics), while on the other hand it decreases their resilience (in the sense of increasing the number of alternative stable states that these communities may end to).
My PhD thesis “Expecting the Unexpected: indicators of resilience as early-warning signals for critical transitions” received the SENSE PhD Award for 2012.
Together with Elisa Benincà from the University of Amsterdam and Chih-hao Hsieh from the National Taiwan University, we are putting together a special session on
in coming July during the ASLO Aquatic Sciences meeting in Japan. George Sugihara of Scripps Institution of Oceanography is going to kick start our session on a tutorial on nonlinear dynamics and the broad spectrum of the rest of the speakers will ensure an interesting and lively session!
Session Topic: Under global environmental pressure, the risk of unwanted changes in aquatic systems is high. Such changes occur across different scales and take a variety of forms depending on the properties of the ecosystem itself. For example, regime shifts may occur among multiple states, communities may change in composition and structure, ecosystem dynamics can shift from stable states to oscillatory regimes. As we still lack proper understanding of the mechanisms behind these phenomena, predicting system changes, anticipating their risk, and above all identifying their main drivers have a crucial role for the conservation and the management of aquatic ecosystems. This session will draw upon the expertise of empirical and theoretical aquatic ecologists to present methods, theories and evidence of understanding and anticipating changes in aquatic systems.
Our colloquium and masterclass on ‘Early-warning signals for critical transitions: bridging the gap between theory and practice’ will be hosted by the Dutch Royal Science and Arts Society (KNAW) from 10 to 12 of October 2012 in Amsterdam.
We have now opened the registration for the masterclass till the end of August!
I just moved to Sevilla in Spain for a postdoc in the lab of Jordi Bascompte http://bascompte.net/