Max Planck Gesellschaft

--- Former member ---

Melanie Kern

Scientist in the Terrestrial Biosphere Modelling Group
room: A3.008
phone: +49 3641 576273
email: mkern(at)

PhD Project and current work

The terrestrial biosphere sequesters currently about 25% of anthropogenic CO2 emissions, which reduces human-induced climate change. Models and observations suggest that this is largely caused by a CO2 fertilization effect on plants, which may be reduced in the future due to progressively increasing nitrogen (N) limitation. However, the extent to such so-called progressive N limitation (PNL) occurs is highly uncertain, and causes major disagreement among model projections of future land carbon (C) uptake. Recent studies have shown that most terrestrial biosphere models (TBMs) have the tendency to overestimate PNL on plant growth under elevated CO2 (eCO2) by lacking a representation of the potential of plants to acclimate to environmental changes, particularly with regard to plant N nutrition and plant N acquisition.
In this context, I focus on two important plant N acquisition strategies, which rely on symbioses, i.e. symbiotic N fixation and mycorrhizal fungi, that are only insufficiently represented in TBMs yet to answer the questions if and to what extent N controls plant growth under current conditions, as well as under rising atmospheric CO2, to improve predictions of future land C uptake.

During my PhD I developed a plant N acquisition model within the TBM QUINCY that allows plants to actively invest C into (i) root uptake of mineral N, (ii) mycorrhizal fungi that export N to their host plants, and (iii) symbiotic N fixers. Following the basic assumption that plants target maximum growth, the model calculates (potential) C costs for each strategy, and allocates available C accordingly to gain most N by investing less C.
As part of the QUINCY project I now investigate the effects of the newly implemented model structure on plant N acquisition and future land C uptake.

Research Interests

  • exchange and interactions between different Earth system spheres
  • C and N cycling within terrestrial ecosystems
  • plant response to N limitation, especially with respect to elevated CO2
  • C allocation and investment into N acquisition
  • mycorrhizal interactions with plants and soil
  • (symbiotic) biological N fixation


since 05/2020 Scientist at the Biogeochemical Signals Department at the Max Planck Institute for Biogeochemistry, Jena, DE

since 10/2016 PhD Student at the Technical University of Munich (TUM), and member of the TUM School of Life Sciences Weihenstephan

since 12/2015 member of the International Max Planck Research School for Global Biogeochemical Cycles

03/2019 – 04/2019 Visiting Scientist at the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, AT

01/2018 – 01/2018 Visiting Scientist at the research group for Plants and Ecosystems (PLECO) at the university of Antwerp, BE

10/2015 - 04/2020 PhD Student at the Biogeochemical Integration Department at the Max Planck Institute for Biogeochemistry, Jena, DE

10/2013 - 09/2015 M.Sc. in Physics of Earth and Atmosphere at University of Bonn, DE

10/2010 - 09/2013 B.Sc. in Meteorology at University of Bonn, DE

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