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Understanding the distribution of tree species in relation to abiotic conditions is central to community ecology. Forest habitats are widely recognized to filter trait variation and according to their habitat preference, with tree species exhibiting different functional strategies in contrasting habitats. With increasing severity and frequency of drought events with climate change, it is crucial to evaluate how tree species from different habitats will respond to drought. We expect tree species specialized in a given habitat to share similar functional strategies that optimizes their local performance, while generalist tree species would express a higher intraspecific trait variability (ITV) that reflects their adaptability across environments. To better understand the interplay between habitat and drought, we suggest a fine ecophysiological approach to discriminate drought vulnerability of tropical tree species depending on habitat preferences. In French Guiana, two main forest habitats co-occur at local scale : terra firme (TF) and seasonally flooded habitats (SFF). They offer contrasting hydrological, topographical and pedological characteristics.We investigated ten leaf functional traits, including water-related traits (water potential at turgor loss point, minimal conductance, saturated water content, stomatal density and venation density) and resource capture traits (leaf area, leaf chemistry) in 279 individuals belonging to 24 neotropical tree species, which included 9 generalist species, 8 SFF specialist species, and 7 TF specialist species. Our preliminary results show that TF specialists tend to have more drought tolerant leaves than SFF specialists. Contrary to our hypothesis, generalist species do not have a higher ITV for water-related traits compared to specialists. Together, our results underline the importance of forest habitat in shaping water use strategies, which can be incorporated in models to better predict tropical tree species responses to rapidly changing climate.

Keywords:

Amazon basin, forests habitats, ecophysiology, drought, tropical trees

Marion Boisseaux, Daniela Krebber, Sabrina Coste, Geraldine Derroire, Claire Fortunel, Paul Mischler, Christine Scoffoni, Angela Casado garcia, Heidy Schimann, Clément Stahl

Presentation within symposium:

S-9 Plant ecophysiology in a changing world: from theory to application

The importance of local habitat in shaping functional tropical tree species’ strategies in the context of climate change.

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