Teaching

In the LPJmL the phenology of crops develops depending on a maximum achievable leaf area index (LAImax), which ranges between 1 and 7. LAImax is also coupled to two other model parameters which represent high yielding varieties and the homogeneity of fields. Roughly speaking, intensive agricultural systems have a higher LAImax, use high yielding varieties and have more homogenous fields than extensive agricultural systems. In LPJmL country LAImax values are calibrated to best fit national yield statistics. The master thesis will research how rainfed and irrigated agricultural yields of major crops and water variables (irrigation needs, evapotranspiration, runoff) vary globally in model simulations for the present time with uniform low and high LAImax and in a simulation with non-uniform LAImax values (calibration values). The aims of the thesis are to i) analyse the sensitivity of yields to the LAImax parameters, ii) quantify the effect of LAImax variance on water variables, iii) evaluate the LAImax values from calibration against knowledge of agricultural intensity. Supervisors: M. Fader and C. Jörges.

Please apply by email to both supervisors with CV and transcript of notes.

The start of crop growing periods in the model LPJmL can be simulated by prescribing sowing dates or internally computing them. The master thesis will research how internally computed sowing dates vary from prescribed (i.e. data-based) sowing dates and how the differences affect length of growing period and yields of major crops, historically, at global level. A comparison with reported yield data will be undertaken. The aims of the thesis are to i) analyse the sensitivity of yields to sowing dates, ii) investigate past trends in sowing dates, iii) recommend the use of flexible or prescribed sowing dates for past simulations with LPJmL. Supervisor: T. Hank and M. Fader.

Please apply by email to both supervisors with CV and transcript of notes.

The model LPJmL uses climate inputs to simulate agricultural, water and biochemical variables. One of the inputs is the precipitation amount. The master thesis will compare the sensitivity of water output variables (evapotranspiration, runoff) and rainfed agricultural yields when using precipitation inputs from the CRU dataset, the GPCC dataset. ERA5 and WFDE5. A systematic comparison between simulation results and measured evapotranspiration and runoff as well as reported yields will be undertaken. An evaluation on what input delivers most realistic model outputs is expected. The research has a global scope and will be done for a recent period of time. The aims of the thesis are to i) analyse the sensitivity of model outputs to precipitation inputs, ii) quantify the effect of current precipitation uncertainty on model outputs, iii) recommend the precipitation output that delivers the most realistic model outputs. Supervisors: M. Fader and E. Probst. Issues: compare the dimension of uncertainty compared to other uncertainties.

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In the model LPJmL harvest residues can be left on the fields or removed along with the actual harvest. The master thesis will compare global simulations of various crops for the past with these two options in regards to legacy effects on soil carbon. The aims of the thesis are to i) analyse the short- and long-term sensitivity of soil carbon to harvest residue management, ii) investigate how residue management has changed in past decades, iii) recommend what assumption on residue management is adequate in what regions of the world. Supervisors: M. Fader and C. Jörges.

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The master thesis will compare global simulations of a world as is versus a world without bioenergy areas where in scenario a) bioenergy plantations will be converted to food production, and in scenario b) bioenergy plantations will be given back to nature. The difference in energy, food production, and vegetation carbon will be quantified. The aims of the thesis are to i) analyse the loss of bioenergy production if bioenergy plantations would be converted to either use. ii) investigate the gain in food production if bioenergy plantations would be converted to food production, iii) investigate the gain in vegetation carbon if bioenergy plantations would be given back to nature. Supervisors: M. Fader and A. Reimuth.

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In the model LPJmL the part of every gridcell that will be used for agriculture, pastures and bioenergy is prescribed yearly through inputs. In the rest of the gridcell (i.e. the part not used by humans) natural ecosystems compete with each other and are, thus, dynamically simulated. The master thesis will investigate the global trends in natural ecosystems as observed in satellite products with the trends in natural vegetation outputs of LPJmL during the past decades. The aims of the thesis are to i) analyse the difference in current natural vegetation as simulated by LPJmL and as observed by satellites, ii) compare historical trends in the evolution of natural ecosystems in the last decades in the model and in satellite data. Supervisors: M. Fader and D. Gampe.

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Most of the coming population growth will happen in the developing world and in urban areas. More people will need more food. Producing additional food through the conversion of natural areas to agricultural areas would seriously affect biodiversity and other ecosystem services. Producing additional food through intensification of current agricultural areas may lead to pollution and soil degradation due to mechanisation and high use of agrochemicals. Vertical farms as closed systems with comparatively low area needs have been proposed as a solution. However, high energy needs and technological challenges have demonstrated to be difficult to solve. The master thesis will summarise the state of knowledge on vertical farms, their potentials and limitations and calculate how many of them would be needed at what locations to supply the food of future population. A preliminary calculation of the energy needs will be undertaken as well. Supervisors: M. Fader and A. Reimuth.

Please apply by email to both supervisors with CV and transcript of notes.