Predicting forest water status under climate change scenarios: A case study in Central Europe

Stockholm

2024

3385

Bandaufführung

40005314

Soils play a major role in the hydrological response of ecosystems. Spatially explicit forest soil attributes are however largely missing in Austria. Therefore, we developed a framework to map soil hydraulic properties and drought stress indices for a forest area of 1 million hectares at a spatial resolution of 10 m x 10 m. We aim to assess water budgets of forest site units for the past 40 years and for two climate scenarios until the end of this century. Our approach combines various data sources: high-resolution digital terrain information, properties of the parent material for soil formation (sub-solum geological substrate) at polygon level, vegetation properties derived from remote sensing, downscaled high resolution climate data and point information (site and soil description of 1800 plots, analyses of physical soil properties of forest floor of five geometric mineral soil horizons of 400 pits). Soil properties were upscaled with digital soil mapping techniques like Artificial Neural Networks. The water balance for 1,800 surveyed forest plots in the study area was modelled with the lumped 1-D- hydrological model LWFBrook90R. Hydrological soil characteristics for the parameterization of the model were derived from pedotransfer-functions. We simulated changes in soil water content, matrix potential, and transpiration deficit as an indicator of stress for a ‘generic’ forest stand. Combining this output with soil and topoclimate information we assessed the site-specific water supply which was then upscaled for the whole study area. To validate the models, we compared their outputs with dendrochronological records available for all plots as well as vegetation indices from the ground-vegetation and site indices derived from stand properties. Dendrochronology provides valuable information on past growth patterns and can help us assess the models' ability to describe physiologically relevant information. Overall, the development of the water balance framework is a promising tool for assessing the impacts of climate change on forest ecosystems. We could show possible impacts on the water balance in a future climate for different scenarios and were also able to identify areas which might be susceptible to future droughts.