Upscaling time series of soil moisture and respiration
Betreuer: Holger Lange
The primary source of carbon dioxide from terrestrial ecosystems is soil respiration. It is well established that soil respiration is strongly dependent on (soil) temperature. Much less knowledge exists on the connection between soil respiration and moisture. One hypothesis is that both very dry and very wet conditions reduce (microbial) soil respiration, due to lack of substrate availability on one hand, and lack of oxygen on the other. But how exactly, and what are the typical soil moisture values (volumetric soil water content) where these limitations are relevant? To investigate these questions, a Norwegian-German-British research project performed automatic measurements for soil temperature, moisture and respiration at high temporal resolution (10 min) at three different sites in Norway since 2017, with four respiration chambers and 12 different soil climate sensors per site. For the master thesis proposed, there are two main tasks: 1. Time series analysis of the data produced in the project. This includes a characterization of the dynamical properties of soil climate and respiration on different time scales in general, and a focus on the soil moisture – respiration relationship in particular. 2. Upscaling of the soil moisture dynamics using soil properties (e.g. texture) and hydrological properties known from a previous soil survey using pedotransfer function, and thereby estimate soil respiration for a spatial grid covering forested parts of Norway. The thesis will be part of a collaboration between the University of Bayreuth (M. Hauhs, H. Lange), the Norwegian Institute of Bioeconomy Research (H. Lange, J. Zhao), the Max-Planck-Institute for Biogeochemistry, Jena (B. Ahrens, M. Pallandt) and the UK Centre for Ecology and Hydrology (T. Marthews), with H. Lange as main supervisor.