A first joint work in my new lab of Jordie Bascompte got published in Nature Communications few weeks ago. By simulating mutualistic communities of 57 empirical plant pollinator and plant seed-disperser networks we identify scenarios where species’ tolerance is extremely sensitive to the direction of change in the strength of mutualistic interaction, as well as to the observed mutualistic trade-offs between the number of partners and the strength of the interactions.
After an invitation by Alan Hastings (editor-in-chief) and a year of preparation, the current issue of Theoretical Ecology is dedicated on Early Warnings and Regime Shifts.
The issue contains 11 original research papers from key contributors of the topic ranging from data analysis, to theoretical considerations, lake ecosystems to disease epidemics. We hope it will have a strong impact in the further development of anticipating regime shifts in complex systems.
There is a lot of interest on the limits of resilience indicators and on whether they are uniquely associated with catastrophic transitions. We tried to shed light on that question in a short piece that just appeared in Oikos. There, we show that the same early warnings may signal non catastrophic transitions, but the same transitions are as well bifurcation points. Thus, it is not surprising that the same expectations for signals of deteriorating resilience are universal prior to any (local) bifurcation. The challenge remains in finding signals that would be specific to the catastrophic, unexpected, and irreversible shifts.
highlighted in Editor’s choice in Oikos
Our long lasting project with the RAYS cohort just got appeared in a review/synthesis paper where we try to summarize basic principles that so far have been widely proposed to be fundamental for supporting the resilience of ecosystem services. Important part of this work is that we try to identify gaps in the existing research on resilience factors based on literature and expert opinion. This effort received quite some enthusiasm so that we decided to extent it into a book.
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. This is also going to be the official kick-off of SparcS – the Synergy Program for Analyzing Resilience and Critical transitionS: an initiative on getting people to work on issues of critical transitions and resilience in a broad range of scientific fields.
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.