Ecosystem functioning is affected by warming, but the number of studies analyzing multiple aspects interactively is very limited. The aims of the workshop were to analyse impacts on ecosystem functioning from various disciplines and to derive a conceptual framework on the joint mechanisms at work, to evaluate available data to provide a quantitative backbone to the framework and to identify knowledge gaps in current research activities.
After bringing data on different aspects together, it seems that at extreme temperature rise, forests seem more susceptible to warming than grasslands. An important tangible outcome is that a scientific paper will be written to describe this phenomenon and to hypothesise about the mechanisms involved. This manuscript is currently being prepared. The intention to write several other manuscripts was expressed.
An important scientific breakthrough is the conclusion from discussions and when comparing available data that die-back of forests at extreme temperature rise is not directly through warming impacts, but seems due to carbon starvation, because warmer conditions in roots lead to enhanced root respiration, which is not compensated for by increased photosynthesis. If this is a general phenomenon, and if it can be proven eco-physiologically, then it will have major impacts for the understanding of the global carbon balance. Another important scientific insight was gained when compared systems that have been warmed for a few years vs. those warmed for decades to centuries as this aids differentiating between effects on intermediate to long term. This comparison suggests that ecosystems may be relatively stable against (extreme) warming, while it is expected that the soil carbon balance may shift. In terms of global carbon sequestration, also this may have important implications.
An important aha moment was when comparing shifts in the microbial communities to warming with those of vegetation, they seemed to be completely decoupled from each other. However, those shifts seemed to be entirely explained by the range of thermal acclimation potential measured by other microbial ecologists. There was almost a perfect match.
We highly enjoyed the format of the workshop. All participants were highly enthusiastic. The high proportion of time dedicated to discussions, the use of walls to draw conceptual diagrams and ideas and to integrate research results and the combination of subgroups and plenary discussions helped to frame ideas and to exchange concepts among disciplines. In addition, we invited a well-known scientist to provide a synthesis presentation at the end of the workshop (Howard Epstein) which was conceived as extremely stimulating to wrap up ideas and to provide alternative views on the topic. We would certainly advice others, who aim for hands-on workshop to follow a similar format.
We do not have other comments, except for a great thank you for all support by the Lorentz Center and additional financial support by KNAW.
Peter van Bodegom (Amsterdam, Netherlands)
Bjarni Sigurdsson (Agricultural University of Iceland)
Ivan Janssens (Antwerp, Belgium)
Hakan Wallander (Lund, Sweden)
Christian Korner (Basel, Switzerland)