Doctoral defence: Slendy Julieth Rodríguez Alarcón “Intraspecific trait diversity in plants: characterizing effects of trait variation on community assembly and ecosystem functioning”

On September 6 at 14:15 Slendy Julieth Rodríguez Alarcón will defend her doctoral thesis “Intraspecific trait diversity in plants: characterizing effects of trait variation on community assembly and ecosystem functioning” for obtaining the degree of Doctor of Philosophy (in Botany and Mycology).

Supervisors: 
Professor Carlos Pérez Carmona, University of Tartu
Research Fellow Riin Tamme, University of Tartu

Opponent: 
Senior Research Fellow Mar Sobral, University of Santiago de Compostela (Spain)

Summary
Climate change will intensify droughts, threatening ecosystem functions and plant diversity by altering species composition and trait values. This highlights the importance of studying plant functional traits, which shape individual performance and ecosystem functioning. Traditionally, ecology has focused on trait differences among species, but intraspecific trait variation (ITV) is crucial in ecological strategies, individual performance, formation of communities (community assembly), and ecosystem functioning. This thesis contributes to the knowledge of ITV above- and belowground and its implications under drought. In a greenhouse experiment with herbaceous species, ITV was greater belowground than aboveground. The roots of individuals within the same species probably differ from each other due to soil heterogeneity. Although ITV remains stable with drought, it triggers changes in values of several traits which reduce the functional space among species, suggesting a convergence towards mixed strategies to withstand drought, knowledge that is essential for understanding community assembly. Extending within-species trait exploration to a natural environment with drought conditions, no strong predictive relationship was found between woody plant traits and individual growth in the Colombian tropical dry forest, as each plant responds uniquely to microenvironmental variation. In these forests, precipitation seasonality and high temperatures select species adapted to these conditions, and it is important for studies to consider trait interactions, especially for deciduous species (those dropping their leaves in the dry season). Overall, the results of this thesis enhance our understanding of the complex dynamics shaping plant strategies above- and belowground in response to water availability. This knowledge is crucial for guiding conservation strategies and predicting the impacts of climate change on the ecosystem functioning.