Max Planck Gesellschaft

Bernhard Ahrens

PostDoc in the Soil Processes Group, Department Biogeochemical Integration and USMILE - Understanding and Modelling the Earth System with Machine Learning
room: C3.013 (tower)
phone: +49 3641 576295
fax: +49 3641 577200
email: bahrens(at)
ResearchGate page:

Research Interests

I have developed the COMISSION model - a continuous, vertically explicit SOC decomposition model that allows for microbial interactions and stabilization via sorption. The objective of the COMISSION model is to improve the representation of processes in SOC profile models that could lead to a long-term persistence of SOC and conventional 14C ages of more than 1000 years in the subsoil.


Peer-reviewed journal articles

Ahrens, B., Guggenberger, G., Rethemeyer, J., John, S., Marschner, B., Heinze, S., Angst, G., Mueller, C.W., Kögel-Knabner, I., Leuschner, C., Hertel, D., Bachmann, J., Reichstein, M., Schrumpf, M. (2020). Combination of energy limitation and sorption capacity explains 14C depth gradients. Soil Biology and Biochemistry, 107912. Download post-print here

Ahrens, B., Braakhekke, M. C., Guggenberger, G., Schrumpf, M., Reichstein, M. (2015): Contribution of sorption, DOC transport and microbial interactions to the 14C age of a soil organic carbon profile: Insights from a calibrated process model. Soil Biology and Biochemistry. DOI: 10.1016/j.soilbio.2015.06.008.

Ahrens, B., Hansson K., Solly E.F., Schrumpf M. (2014): Reconcilable differences: a joint calibration of fine-root turnover times with radiocarbon and minirhizotrons, New Phytologist, 204, 4, 932-942.

Ahrens, B., Reichstein, M., Borken W., Muhr J., Trumbore S.E., Wutzler, T. (2014): Bayesian calibration of a soil organic carbon model using Δ14C measurements of soil organic carbon and heterotrophic respiration as joint constraints. Biogeosciences, 11, 2147-2168, doi:10.5194/bg-11-2147-2014.

Ahrens, B., Reichstein, M. (2014): Reconciling 14C and minirhizotron-based estimates of fine-root turnover with survival functions, Journal of Plant Nutrition and Soil Science, 177, 2, pp 287-296, doi: 10.1002/jpln.201300110.

Borken, W., Ahrens, B., Schulz, C., Zimmermann, L. (2011): Site-to-site variability and temporal trends of DOC concentrations and fluxes in temperate forest soils, Global Change Biology, 17: 2428–2443. doi: 10.1111/j.1365-2486.2011.02390.x

Braakhekke, M. C., Beer, C., Schrumpf, M., Ekici, A., Ahrens, B., Hoosbeek, M.R., Kruijt, B., Kabat, P. and Reichstein, M. (2014) The use of radiocarbon to constrain current and future soil organic matter turnover and transport in a temperate forest. Journal of Geophysical Research: Biogeosciences, DOI: 10.1002/2013JG002420.

Braakhekke, M.C., Wutzler, T., Beer, C., Kattge, J., Schrumpf, M., Ahrens, B., Schöning, I., Hoosbeek, M.R., Kruijt, B., Kabat, P. and Reichstein, M. (2013): Modeling the vertical soil organic matter profile using Bayesian parameter estimation. Biogeosciences, 10, 399-420.

Carvalhais, N., Forkel, M., Khomik, M., Bellarby, J., Jung, M., Migliavacca, M., Mu, M., Saatchi, S., Santoro, M., Thurner, M., Weber, U., Ahrens, B., Beer, C., Cescatti, A., Randerson, J. T., Reichstein, M. (2014) Global covariation of carbon turnover times with climate in terrestrial ecosystems. Nature, 514, 213-217.

Camino-Serrano, M., Gielen, B., Luyssaert, S., Ciais, P., Vicca, S., Guenet, B., Vos, B. D., Cools, N., Ahrens, B., Altaf Arain, M., Borken, W., Clarke, N., Clarkson, B., Cummins, T., Don, A., Pannatier, E. G., Laudon, H., Moore, T., Nieminen, T. M., Nilsson, M. B., Peichl, M., Schwendenmann, L., Siemens, J., Janssens, I. (2014): Linking variability in soil solution dissolved organic carbon to climate, soil type, and vegetation type. Global Biogeochemical Cycles, 2013GB004726.

Thurner, M., Beer, C., Santoro, M., Carvalhais, N., Wutzler, T., Schepaschenko, D., Shvidenko, A., Kompter, E., Ahrens, B., Levick, S.R. and Schmullius, C. (2013) Carbon stock and density of northern boreal and temperate forests. Global Ecology and Biogeography.

Conference contributions

Ahrens, B., Braakhekke, M.C., Guggenberger, G., Schrumpf, M.,, Reichstein, M.: The contribution of sorption, DOC transport and microbial interactions to the 14C age of SOC profiles as assessed by the process model COMISSION. Oral presentation. SUBSOM-Symposium 2015, Schloss Raesfeld, Germany: 28.04. - 01.05.2015

Ahrens, B., Schrumpf, M., Reichstein, M.: Sensitivity of Deep Soil Organic Carbon Age to Sorption, Transport and Microbial Interactions – Insights from a Calibrated Process Model. Oral presentation. AGU Fall Meeting 2013, San Francisco, USA: 09.12. - 13.12.2013; First Presentation of the COMISSION Model

Ahrens, B., Reichstein, M.: Modelling fine-root turnover times with radiocarbon and survival functions. Oral presentation in German. German Soil Science Society (DBG) Annual Meeting 2013, Rostock, Germany: 07.09. - 12.09.2013

Ahrens, B., Borken, W., Muhr, J., Savage, K.E., Wutzler T., Trumbore, S.E., Reichstein, M.: Bayesian calibration of a soil organic carbon model with radiocarbon measurements of heterotrophic respiration and soil organic carbon as joint constraints. Oral presentation. European Geosciences Union General Assembly 2012, Vienna, Austria: 22.04.2012 – 27.04.2012

Ahrens, B., Borken, W., Muhr, J., Schrumpf, M., Savage, K.E., Wutzler T., Trumbore, SE, Reichstein, M.: Modeling Soil Organic Carbon Turnover in Four Temperate Forests Based on Radiocarbon Measurements of Heterotrophic Respiration and Soil Organic Carbon. Poster presentation AGU Fall Meeting, San Francisco: 05.12.2011 – 09.12.2011

Borken W., Ahrens, B., Schulz, C.: Long term trends of DOC in throughfall and soil solution of 22 temperate forests. Poster presentation. BIOGEOMON, Helsinki: 29/06/2009 – 03/07/2009.

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