C02
Modulation of soil water fluxes by changes in vegetation properties and management
Prof. Dr. Frank Ewert
University of Bonn | +49 228 73-2041 |
Dr. Thomas Gaiser
University of Bonn | +49 228 73-2050 |
Prof. Dr. Guillaume Lobet
Forschungszentrum Jülich | +49 2461 61-9013 |
Summary
We will investigate the impact of changes in agricultural and forest management during the last decades on land surface – atmosphere interactions. We will improve the parameterization of land surface model CLM so that it can reproduce the effects of changes in management on regional heat, water and carbon fluxes. Therefore, we will link a suite of models starting from mechanistic single plant models that couple carbon and water flow within the plant with the external environment over specific crop models at the field scale to the Community Earth System Model CLM.
Graphical summary
Contribution to the CRC
Our project will closely collaborate with C03, where maps of CLM 5.0 ecosystem parameters for different plant functional types (PFTs) will be estimated from observations; results will be compared and used to validate our bottom-up approach and will provide mechanistic approaches for improving the carbon partitioning in CLM 5.0. We will also closely collaborate with D03 in a bottom-up forest representation in CLM and with B05 in the development of crop-specific irrigation timeseries. Also, the results of our simulations regarding potential yields under optimum water and nutrient supply for specific crops in historical periods will serve as an input for project A05.
Approach
The central hypothesis of this project is that changes in agricultural and forest management during the last decades have had strong impacts on land surface-atmosphere interactions and therefore need to be accounted for in land surface models. To test this hypothesis, we will use the mechanistic whole-plant model CPlantBox, to simulate water and carbon fluxes at plant and field scale and evaluate the interactions between crop development, climate, and management that emerge. The results obtained from the simulations with CPlantBox will be used to parameterize the field-scale crop model SIMPLACE <LintulCC2>, first on the field scale and later the continental scale. SIMPLACE <LintulCC2> will further be used to estimate agricultural management and plant phenology parameters. Results from the plant and field scale models will be used to assess whether CLM can represent the effect of the emerging water and carbon interactions on crop development accurately. Finally, using the newly developed upscaling approach we will integrate an explicit representation of carbon and water fluxes into CLM and perform multi-annual simulations at continental scale.
The data needed to parametrize, calibrate, and validate the models across scales will be obtained from a literature review on root hydraulics, a long-term experiment with rotating crops and varying cultivars and timeseries from sites where carbon and water fluxes and crop development are measured across Europe (TERENO and FluxNet). To complete these calibration data sets, we are conducting two field experiment with wheat and rye cultivars from different decades, to investigate changes in canopy structure, assimilate partitioning between above and below ground plant parts and the impacts of stress factors like water stress on crop growth and assimilate partitioning.
Main results in 2022
A database on root hydraulic properties was developed, based on an extensive literature review of experimental studies of root-segments, individual roots, and whole root systems. The database will be used to improve the parameterization of the root water uptake model for different plant functional types, across scales.
Setup of the field experiment at the experimental research station of the University of Bonn, Campus Klein-Altendorf
Main results in 2023
Results of the first experimental year were obtained and the second year of the field experiment was set up. Meanwhile first test simulations with newly developed routines are conducted.
Publications:
- A sensitivity analysis of the crop model SIMPLACE<LintulCC2> was presented at the DBG annual meeting (https://www.dbg2023.de/assets/dgb-2023-abstractband-2023-08-17.pdf),
- A paper about combining root and soil hydraulics in macroscopic representations of root water uptake was published in the vadose zone journal (https://doi.org/10.1002/vzj2.20273)
Main results in 2024
The field experiment is in its last year and publications of the experimental data and first combined simulation exercises are being prepared.
First results are being published:
The database on root hydraulic properties was published in PlantDirect (https://doi.org/10.1002/pld3.582)
First results from the field experiment and a new routine for the simulation of carbon partitioning in crops were presented as a poster at the EGU2024 (https://doi.org/10.5194/egusphere-egu24-16031)
First results of root architectural differences between the cultivars investigated in the experiment were published at the EGU 2024 as oral presentation (https://doi.org/10.5194/egusphere-egu24-7991).
A paper about mechanistically derived macroscopic root water uptake functions was published in the vadoze zone journal (https://doi.org/10.1002/vzj2.20333)
