Soil properties from geographic databases : a prerequisite for soil water balance mapping in European Forests

PI : Joseph Levillain (UMR INRA-UL 1137 Forest Ecology and Ecophysiology — EEF)

Collaboration :
Vincent Badeau, Nathalie Bréda, Alain Bénard (EEF)
Christine Le Bas (INRA-US Infosol)
Noémie Pousse (ONF Département Recherche & Développement)

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Context — In a context of climate change inducing more frequent and more severe drought events in many parts of the world, an increased plant water shortage is expected (Nemani et al. 2003; Schär et al. 2004). In France, past recurrent or extreme drought events have been clearly identified as the hazard-inducing cycles of forest dieback and mortality of vulnerable trees (Levy and Becker 1987; Bréda et al. 2000; Bréda and Badeau 2008; Badeau et al. 2010). Indeed, drought events generate soil water deficits that induce (1) regulation of gas exchanges through stomatal regulation, i.e. reduction of carbon fixation and climate change mitigation and (2) cessation of their growth , i.e. reduction of carbon storage (Bréda et al. 1993; Bréda et al. 1995; Bréda and Granier 1996; Granier et al. 2000). In case of long or intense water deficits, trees adaptation is insufficient and irreversible damages occur compromising tree health and sometimes survival (Bréda et al. 2006). Thus, it is important to understand the vulnerability and regional adaptability of European forests, the scientific community investigates only recently that field (Lindner et al. 2014). The spatial and temporal quantification of soil water deficit is a key factor to understand and anticipate the impacts on forest health and productivity.

Objectives — This project aims to focus research on modeling for forest soil water balance to better understand soil water deficit distribution depending on variations of soil types, climate conditions and forest types.

Approach —BILEUROPE proposes establishing sampling strategies for building geographic databases to define soil properties required by BILJOU©, the recently developed forest soil water balance model. From a computational perspective, all necessary modeling adjustments will be studied to optimize water balance time calculations for large data sets. For quantitative and geographical assessments of water deficit severity in European forest stands, drought distribution indicators will be analyzed, as computed by BILJOU©.

Expected results and impacts — The challenge will be to characterize soil properties of European forests using available geographical databases in order to create comprehensive drought maps. These maps will prove useful for the broader international scientific community working on forest health and forest productivity, water and carbon storage ecosystem services, and species distribution for past, present and future climate conditions.