iCUE-Forest (“Improving tree carbon use efficiency for climate-adapted more productive forests”) is a EU H2020 Marie Skłodowska-Curie project exploring the effects of changes in climate and tree species distribution on wood productivity and carbon stocks.


Wood production depends on how effectively plants convert atmospheric carbon dioxide (CO2) into wood. Moreover, forests mitigate climate change through their net carbon uptake from the atmosphere. Both these forest functions are crucially dependent on tree carbon use efficiency (CUE). Thus, within the iCUE-Forest project we will first identify the drivers of changes in CUE and then develop approaches to increase CUE to enhance wood productivity and carbon stocks under future climatic conditions.


We aim to inform forest managers on species that will be optimally adapted to future climate in northern boreal and temperate forests. For this purpose, we will:

  1. Develop novel data-driven estimates of plant respiration (or autotrophic respiration; Ra), net primary production (NPP) and tree CUE based on recent satellite-driven maps of tree living biomass (Thurner et al., 2014; Thurner et al., 2019), extensive databases of field measurements on plant traits that allow to infer respiratory costs per unit biomass, and temperature datasets
  2. Investigate the spatial patterns in CUE under current climate and forest management in order to quantify how CUE varies for different tree species and current environmental conditions
  3. Apply a dynamic global vegetation model (DGVM) to predict temporal changes in CUE in response to climate change and tree species distribution scenarios


Tree CUE is defined as the ratio of net to gross primary production (NPP / GPP; Manzoni et al., 2018). In recent decades, vegetation productivity has been increasing. However, in view of the unknown response of plant respiration (Ra) to future climate conditions, a continued ncrease in NPP (= GPP – Ra) and CUE in forest vegetation is highly uncertain. Despite the urgent need to inform forest managers on the expected changes in these carbon fluxes and carbon cycle properties, estimates of current regional to global plant respiration levels are missing, since this carbon flux is hardly measurable in the field at such spatial scales. This shortcoming essentially contributes to the high uncertainty in NPP and its response to climate change simulated by DGVMs (Thurner et al., 2017).


The project’s concept and preliminary results have been presented at the GINKGO Workshop „Opportunities from New Data for Vegetation Modeling“ (UFZ Leipzig, October 2020) and will also be presented at the European Geosciences Union (EGU) General Assembly (Vienna, 30 April 2021, https://meetingorganizer.copernicus.org/EGU21/EGU21-10299.html).

Previous work

Thurner, M., Beer, C., Crowther, T., Falster, D., Manzoni, S., Prokushkin, A., Schulze, E.-D. (2019): Sapwood biomass carbon in northern boreal and temperate forests. Global Ecology and Biogeography, 28, 5, 640-660. https://doi.org/10.1111/geb.12883

Manzoni, S., Čapek, P., Porada, P., Thurner, M., Winterdahl, M., Beer, C., Brüchert, V., Frouz, J., Herrmann, A.M., Lindahl, B.D., Lyon, S.W., Santruckova, H., Vico, G., Way, D. (2018) Reviews and syntheses: Carbon use efficiency from organisms to ecosystems – Definitions, theories, and empirical evidence. Biogeosciences, 15, 5929–5949, https://doi.org/10.5194/bg-15-5929-2018

Thurner, M., Beer, C., Ciais, P., Friend, A.D., Ito, A., Kleidon, A., Lomas, M.R., Quegan, S., Rademacher, T.T., Schaphoff, S., Tum, M., Wiltshire, A., Carvalhais, N. (2017): Evaluation of climate-related carbon turnover processes in global vegetation models for boreal and temperate forests. Global Change Biology, 23, 8, 3076-3091. https://doi.org/10.1111/gcb.13660

Thurner, M., Beer, C., Santoro, M., Carvalhais, N., Wutzler, T., Schepaschenko, D., Shvidenko, A., Kompter, E., Ahrens, B., Levick, S.R., Schmullius, C. (2014): Carbon stock and density of northern boreal and temperate forests. Global Ecology and Biogeography, 23, 3, 297-310. https://doi.org/10.1111/geb.12125

Project partners

Dr. Martin Thurner (Principal investigator, SBiK-F Frankfurt)

Prof. Dr. Thomas Hickler (Host, SBiK-F Frankfurt)

Prof. Dr. Christian Beer (Cooperation partner, Universität Hamburg)

Prof. Dr. Stefano Manzoni (Cooperation partner, Stockholm University)

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 891402.