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Rôle des communautés microbiennes dans la dégradation de la matière organique en forêt dans un contexte d'exportation intense de biomasse

Abstract : One of the main usages of wood in Europe is renewable energy supply that implies intensification of forest management to respond to this increasing demand. However, the impact of intense forestry practices on soil microbial communities remains poorly investigated. In the frame of my PhD thesis, I evaluated effects of artificial organic matter removal on functional and taxonomical diversity of soil bacterial and fungal communities in temperate forest, using six experimental sites across France (INRA MOS experimental network). In parallel, I also characterised impact of intensified forest management practices on functional microbial communities in tropical plantation of Eucalyptus trees. This work permitted to identify several sensitive functional indicators of organic matter degradation. Notably, the degradation of chitin – a nitrogen polymer main component of arthropods and fungal cell walls – was revealed to be particularly sensitive to organic matter removal. Genomics and enzymatic approaches were then used to estimate chitinolytic potentials of the different genera of soil fungi. In controlled conditions, we were able to quantify ectomycorrhizal fungus carbon and nitrogen mobilisation and transfer capacities from chitin enriched organic matter to its host during symbiotic interaction. Finally, we evaluated chitinolytic functions of ectomycorrhizal fungi at large scale by combining enzymatic and isotopic approaches. Taken together, the results acquired in the frame of my PhD thesis, illustrate the significant role of ectomycorrhizal fungi in carbon and nitrogen mobilisation from organic matter. We particularly highlight that microbial compartment in soil must be considered in studies of forest management practices
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Francois Maillard. Rôle des communautés microbiennes dans la dégradation de la matière organique en forêt dans un contexte d'exportation intense de biomasse. Biologie végétale. Université de Lorraine, 2018. Français. ⟨NNT : 2018LORR0190⟩. ⟨tel-01997656⟩

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