Master or Bachelor student internship
Soil organic matter (SOM), including carbon (C) and nitrogen (N), are pivotal for ecosystem functioning and the provision of ecosystem services such as climate regulation and soil fertility. SOM is extremely heterogeneous, and therefore often operationally separated into pools with different residence times, varying from minutes to millennia, and that are of different ecological relevance. Plants constitute the primary contributor to the terrestrial SOM pools, but they vary widely in their chemical composition, which is an important control on decomposition rate as well as the SOM pool the litter will eventually be integrated in. There remains considerable debate, though, as to whether litter compounds that decompose rapidly (labile compounds) or those that decompose slowly (recalcitrant compounds) end up in SOM pools with short versus long residence times. Answering this question is pivotal to design successful management strategies targeted towards increasing soil organic C (‘climate change mitigation”) or N (‘soil fertility’).
To investigate this issue, we propose a project in which the student investigates the fate of litter C and N in different soil fractions under the influence of plant residues with variable biochemical composition (roots and leaves). The 13C isotopically enriched leaf and root litters will be tracked at different moments in the decomposition process. The transplantation of 13C isotopically enriched litter from some microcosms to other microcosms will allow to study which SOM pools are nourished by the litters are a given decomposition phase. Besides helping with the setup and maintenance of the experiment, the student will further learn soil fractionation techniques, analyze data and test some of the predictions for plant effect on C stabilization processes in soil.
The internship would start early 2024.
Supervision: Raoul Huys and Grégoire Freschet (CNRS Researchers)
Contact email : raoul.huys@cnrs.fr
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