- Forest ecology
- Population ecology
- Plant functional traits and ecophysiology
- Population genetics
- Statistical modeling
- Biodiversity conservation and management
Understanding the structure, function and persistence of relict populations under climate change
Funded by: EU − Marie Skłodowska-Curie Individual (IF-EF) Fellowship (H2020-MSCA-2014; Project 656300-PERS‒RELICT‒CLIM).
Climate change-type drought is disrupting population performance and the distribution of tree species across the globe. Biogeographical theory suggests that rising global temperatures should drive species to move poleward and upward in elevation as they track the climates to which they are adapted. Consequently, one fundamental climate change prediction is that population loss and regional extinctions of tree species should occur in the most drought prone areas of their ranges (i.e. the rear range-edge). This prediction assumes that rear-edge populations are marginal with higher risk of extinction than those populations at the core of the species' because they occur at reduced population sizes along less favorable habitats for the species. This assumption is supported by a broad range of studies in the literature that document altered tree growth and mortality in response to increased drought conditions. However, evidence of rear-edge populations persisting in the most marginal and drought-prone habitats is increasingly accumulating. For example, relict populations are one of the most impressive cases of rear-edge population persistence as they persist geographically isolated in marginal climates significantly hotter and dryer than that tolerated by the species. The disparity of documented responses at species rear range-edges is potentially a result of complex ecological and evolutionary factors that determine population dynamics, and points out the need for a proper understanding and assessment of marginality and the identification of the key mechanisms implied in population persistence.
In this project we aim to propose a framework for research design and analysis at species' rear range-edges, and we then aim to demonstrate how the framework improves our understanding of marginality and rear-edge population dynamics. In order to put into practise the framework we have established our study system at the rear range-edge of the European beech tree (Fagus sylvatica L.), a species with a high ecological importance yet highly drought sensitive. The species occurs along the transition between the Mediterranean and temperate biomes, where beech populations are distributed across a fragmented landscape and along highly heterogeneous ecological conditions. In this region, relict beech populations persist geographically isolated in marginal habitats out of the species' physiological tolerances. This project represents a significant advance in population ecology and biogeography, while the information gained will be relevant to improve our ability to understand the impacts of climate change at the rear-edge of species distributions and to predict their consequences, from regional extinctions and trophic cascades to carbon and water dynamics.