The Likens' problem: a journey in systems ecology

To provide a narrative, I have framed the contributions of this habilitation thesis in the Likens’ problem. Indeed, the research program evolved toward understanding how plant stress controls the fluxes of elements by underground and surface fluxes in small catchments.

While the structural model of the original Hubbard Brook experiment was simple and pragmatic, our work started from an overwhelmingly complex holistic approach. The theoretical and methodological contributions aimed to reduce the approach’s dimensionality and meaningfully focus on biological compartments with key roles in the target biogeochemical processes.

This effort led to a modular research strategy combining processes over scales and discretization in ecological objects, several experimental scales, and nested grids of fieldwork sampling, which was applied to areas contaminated with heavy metals. 

Not mentioned in the presentation, but equally crucial for the program’s success was the hybridization between the Romanian fieldwork tradition and the experimental rigor of the Jena School of bio-geo interactions in mining areas. More information can be found at https://zenodo.org/records/13684611 

This kind of work is interdisciplinary by its very nature, spanning from ecophysiology to catchment scale modeling. It becomes transdisciplinary when developing the needed research ecosystems and transferring knowledge describing ecosystem services to decision-makers.

The specific conclusions in each direction have been summarized in the concluding part of the habilitation thesis, available at https://zenodo.org/records/13684356. The research directions will be developed with the Hubbard Brook research ecosystems and the Jena Bio geo interactions school in the frame of a European network.

Note: This is the final defended version of the presentation of the habilitation thesis. A few slides from the initial form have been moved to supplementary slides, and a slide about the co-tutorship of PhD students and research funding has been inserted. The sections are better delineated, together with a few other formatting changes, for the clarity of the presentation.