Editor’s choice May

Oikos will publish synthetic meta-analyses open access and with high priority, and has assigned Christopher Lortie as deputee editor responsible for handling and inviting such contributions.  Jodi Price and Meelis Partel used meta-analyses to examine experimental evidence that functional similarity between invaders and resident communities reduces invasion. They found evidence for forb species but not for grasses, but equally important, their study highlights the fact that such patterns are more prominent in artificially assembled communities than in more natural communities with species or functional groups removed. Only by synthesing data from multiple studies the authors can unambiguously demonstrate that ecological mechanisms that are both theoretically and empirically underpinned may be only limited expressed under natural settings.

As a second editor’s choice we selected a theoretical study by Sonia Kefi and co-authors exploring to which degree critical slowing down is a key phenomenon to measure the distance to a tipping point in ecosystems. Tipping points are abrupt, unexpected and irreversible shifts within ecosystem. Specific ecosystem characteristics like spatiotemporal changes in biomass or population sizes may provide hints or early warning signals about an approaching shift. There is indeed a quickly expanding literature suggesting the presence of such early warning signals. By using analytical modelling, the authors demonstrate that -contrary to the ruling perspective- early warning signals based on critical slowing down are representative for a broader class of situations where systems experience increasingly sensitivity to perturbation. They are hence not solely specific to catastrophic shifts. This study consequently warns for a careful interpretation of critical slowing down as an early warning signal. It thereby stimulates further research aiming at developing and interpreting alike indicators to catastrophic ecosystem shifts whose occurrence may be extremely important for the livelihood of people living in such threatened ecosystems.

Editor’s Choice papers are freely accessible online for three months.