Investigating the importance of extreme climatic events on plant species temporal turnover: A study of European alpine ecosystems.

Climatic extremes, (i.e. perturbations in the climatic environment relative to the norm) can have strong ecological consequences on plant assemblages and ecosystem function, facilitating species temporal replacement patterns. The influence of climatic extremes is increasing in importance. Near to mid-term climate forecasts (50 - 150 years) anticipate a decline in climatic stability as periods spent under unusual climatic events increase in frequency. Climatic extremes have however received less focus relative to the study of climatic long-term trends and variation in governing vegetation dynamics and structure. Improving our understanding therefore, of how extreme climatic events influence vegetation dynamics, in particular compositional changes via temporal species replacements requires investigation. This project intends to bridge this knowledge gap. With a focus specifically on European alpine ecosystems, of which contain a large part of the global biodiversity and also make up large proportions of the Norwegian landscape, the project proposes to model the frequency of extreme climate events across geographically distinct European mountain ranges. This will be achieved thorough exploring a simple yet novel means for quantifying the frequency of extremes (i.e. fat-tails of temporal distribution patterns). Climatic perturbations should consequently feedback to individual species and functional responses over time but exactly how is not obvious a priori. To study these processes across a broad latitudinal gradient, the project will synthesise existing alpine vegetation datasets, quantify temporal beta diversity and use the climate extreme model as an explanatory factor. Beta diversity will be explored using a partitioning framework, disentangling processes influencing richness gradients and true replacement patterns. The result will be a better understanding of causes and the drivers of change in alpine plant diversity and community composition.