Quantum Leap for Soil-Plant interaction Models

PI: Laurent Saint-André ( UR 1138 BEF)

Co-applicants:  D. Bonal (EEF), J-D. Bontemps (LERFOB)

Collaborations: M. Barrandon and A. Henrot (IECN, France), E. Dufrêne (ESE, France), Y. Nouvellon and JP Laclau (ECO&SOLS, France), C. Deleuze (ONF, France), M. Tomé (Instituto Superior de Agronomia, ISA, Portugal), W. Kutsch (Johann Heinrich von Thünen Institut, vTI, Germany), H. Sverdrup (Institutionen för ekologi, ULUND, Sweden), A. Gessler (Leibniz-Zentrum für Agrarlandschaftsforschung, ZALF, Germany), Q. Ponette and M. Jonard (Université Catholique de Louvain la Neuve, UCL)

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Context — Mitigation and adaptation measures in forests to counter the effects of global climatic changes and provide a sustained and renewable source of energy is a high priority in Europe. Unfortunately, still missing is a robust metric system capable of comparing the impacts forest management can have on the different ecosystem services. Scientifically, the challenge is to take in to account to existing interactions between C sequestration and other forest ecosystem services (water quality and quantity, soil fertility and protection, recreation).

Objectives — QLSPiMs aims to fill this gap as a soil-plant interaction model designed to help the forestry sector to assess the long-term impacts of global changes and to address the associated economic challenges resulting from these changes..

Approach — To meet these objectives and to provide all of the indicators related to the ecosystems services implicated in the project (wood production, carbon sequestration, water provision and related quantity / quality), the strategy adopted by QLSPiMs is supported by three main themes:  (i) an interdisciplinary approach combining ecophysiology, forestry, biogeochemistry, microbiology to further our knowledge about the impacts of soil nutritional status and soil water availability on tree functioning, with a specific focus on roots; (ii) an innovative modeling methodology which combines concepts, reexamines the underlying hypotheses of existing models and benefits from a highly diverse of selection of modeling approaches; (iii)  emphasis on connectivity between theory, process-based modeling, and statistically-assisted observation to explore patterns of dose-response curves to water, nutrient and energy resources related to integrated traits of tree communities.

Key Results — 2015 update pending

Outstanding results this first year (the project was launched in February 2013) allowed us (i) to obtain co-financing for two theses; EFPA Department supporting one thesis, the Region of Lorraine the other, (ii) to identify thematic priorities (QLSPIMS workshop days held on 15 and 16 April, 2013 launched working groups from November 2013 following the recruitment of two theses and post-doc), (iii) to achieve a synthesis on soil-plant models, demonstrated during the Journées REGEFOR (Saint-André et al. 2013), (iv) to replace the concept of fertility index used in the phenomenological models with a production-environment relationship and to further evaluate the contribution ecophysiological models  to study these relationships on a larger scale (Bontemps and Bouriaud, 2013), (v) to introduce phenology in growth models to phenomenological basis via a cohort generic model  tested on beech, oak and Eucalyptus (Sainte-Marie et al 2012, 2013 a,), (vi) a theoretical mathematical analysis on the decomposition of litter and soil organic matter model (coupled C and Nfocused on microbial activity) to Agren and Bosatta, 1998 and obtain a solution in 2D (vertical integration of carbon and nitrogen in the soil) compatible with phenomenological models (Sainte-Marie et al. 2013 b), (vii) analyze concepts present in the models FORSAFE and NUCAM (G. Van Der Heijden in LUND post-doc) to be able to then introduce them in a soil module to be developed during in 2014 (QLSPIMS post-doc recruitment is ongoing ), (vii) to study the effect of drought on fertilized stands showing differences between calcium intake (decreased or even cancelled altogether by drought) and nitrogen (negative effect on growth in the event of drought).

Prospects for 2014 —The arrival of two PhD students (Alexandre Fruleux on the topic ‘Root development’, Yoran Bornot on the topic “Effect of the nutritional status of trees on their resilience to drought”) and post-doc (currently under recruitment on “modeling of bioavailability of mineral elements in the soil”) will launch the work cycle in groups. Selected sites will focus on the mechanisms relating to (i) the dynamics of organic matter in the soil (including the relationship between the parameters of the models and microbial diversity), (ii) the impact of the availability of mineral nutrients and water over the life of the leaves, photosynthesis, LAI as well as on growth and the root turnover. This work on mechanisms is accompanied, in parallel, with work on the formalism of models (their theoretical and mathematical frameworks for mapping responses to the environment). The work methodology involves three steps: precise analysis of published research and literature to extrapulate the major concepts, testing of hypotheses via modeling and / or by experimentation and integrating the results into a new generation of phenomenological models.