Mögliche Themen für B.Sc. und M.Sc. Arbeiten in der Abt. Bioklimatologie
Bei Interesse kontaktieren Sie bitte den/die entsprechende/n Wissenschaftler/In.
Manche unten aufgelisteten Themen können als B.Sc. oder M.Sc. Arbeit bearbeitet und thematisch dementsprechend auch angepasst werden. Eigene Vorschläge für Themen sind auch immer willkommen.
Frequent and intense drought conditions have altered the productivity, structure and susceptibility of our forests leading to large-scale tree mortality. In this scenario, it is essential to understand energy and water fluxes at the ecosystem scale to be able to predict changes in forest ecosystems and to support future forest management decisions. In this study, we aim to understand the water fluxes by combing the eddy covariance and species specific hydraulic approaches. This thesis is offered by the Department of Plant Ecology and Ecosystems Research in close collaboration with the Department of Bioclimatology. Please find more information here.
In April, the herbal understory vegetation emerges in the Hainich forest. A relatively large amount of solar radiation reaches the forest floor increasing the photosynthetic activity of the herbal layer, since the deciduous trees are still without leaves. In the overstory, the leaves only start to emerge in late April/early May. In this thesis project, the photosynthetic CO2 uptake of the herbal layer should be quantified during the beginning of the vegetation period (April-May). For that, measurements should be obtained with the LI-6800 Portable Photosynthesis System at several plots and on multiple days. Moreover, the species composition and degree of coverage of each plot should be determined. Finally, the CO2 uptake by the herbal layer can be compared with estimates of CO2 release by soil respiration and with the CO2 exchange of the entire forest ecosystem.
We have obtained optical LAI measurements with a LI-2000 for multiple years. These data should be processed, analyzed and extended by additional new measurements, so the dynamic of the canopy can be compared between years and seasons. Furthermore, these data can be compared with digital hemispherical photos, satellite data of EVI, PAR radiation measurements above and below the canopy, and ecosystem flux measurements obtained with the eddy covariance method.
We take every half hour photos of the canopy top at our forest study sites Hainich and Leinefelde. Based on these time series of photos, periods of leaf out, leaf fall, snow cover etc. can be determined automatically and compared between years and sites. The thesis would include scripting an analysis tool (in R or python, e.g. usage of phenopix R package) to determine such main events in the forest. Furthermore, the analysis could focus on individual trees in the photos.
We obtain CO2 concentration measurements with various infrared gas analyzers at our study sites. These analyzers tend to drift in their measurement accuracy and precision with time, thus, a regular calibration is needed. In this thesis project, the concentration data will be reanalyzed considering the instruments’ offsets detected by each calibration and the drift between two calibrations. The impact of this concentration correction on estimated annual ecosystem fluxes should be quantified.
The so-called RothC model describes the turnover of organic material in the soil and the dynamics of soil carbon. Based on biochemical and meteorological measurements the model can be set up and interrelations with soil temperature, moisture and material composition can be analyzed. The model output (soil CO2 efflux) can be compared to soil respiration measurements obtained with an automatic chamber system. Thus, the RothC model can be evaluated for the application to forest sites.