PriOrity Effect Mechanisms (POEM): interactive effects of assembly history and weather conditions on the creation and persistence of priority effects in dry acidic grasslands

• Applicant: Professorin Vicky Martine Temperton, Ph.D.
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 420444099

Recent ecological research has highlighted that history in ecology matters more than we previously thought. Evidence shows that the order and timing in which different species join communities can significantly alter interaction outcomes, a phenomenon known as priority effects. Within the POEM project we have set up a long-term field experiment that investigates the role of order of arrival of different plant functional groups and year of initiation on biodiversity and ecosystem function outcomes in dry acidic grasslands. Here we set up the exact same experiment in consecutive years, to allow us to study effects of weather in interaction with priority effects. We have found effects of order of arrival pf plant functional groups on belowground rooting dynamics, whereas aboveground outcomes are less clear (except on community composition) so far. The year in which each sub-experiment is established (year of initiation effect) is expected to affect plant assembly outcomes and hence also ecosystem functions and biodiversity. Understanding the temporal dynamics and underlying mechanisms of priority effects is an essential next step to improve our ability to predict community changes in the context of global environmental change (especially climate change), and thus to contribute to successful restoration strategies. To date, evidence from most priority effect experiments is based on short-term responses often not in the field, with a strong focus on aboveground community characteristics rather than belowground. In addition, hardly any field experiments exist that study the interactive effect of year of initiation with priority effects. In POEM II we will make use of the existing POEM platform by prolonging our time-series and by adding new components that allow us to better understand the relative importance of initial weather conditions during the year of initiation for community trajectories and ecosystem functions. Specifically, we aim at exploring temporal shifts in the direction and strength of priority effects on above- and belowground response and how they are modulated by varying weather conditions. The POEM platform allows us to focus on the persistence of both below- and aboveground responses over longer time periods as well as elucidating year of initiation effects on establishment and hence priority effects.

• DFG Programme: Research Grants