BOWA-CH: Soils and water regime of Swiss forests and forest sites under present and future climate

Rising temperatures and droughts projected in climate change scenarios for Switzerland are a potential threat for forest plant communities. However, it is not clear today how, where and to which extend Swiss forests may change in the future by these developments. Modelling the water and energy fluxes in the atmosphere-plant-soil systems under current and future climate plays a key role in this context.

Soil properties relevant to hydropedological processes are essential for modelling the water regime of forest stands. However, for modelling these processes, it is first necessary to overcome the lack of spatial information on these properties for the forested area of Switzerland. One of the goals of the BOWA-CH project is therefore to generate high-resolution spatial information of Swiss forest soils from legacy soil data and environmental covariates by digital soil mapping (DSM) techniques. The project then aims to predict by water balance modelling the drought risks for Swiss forests for the expected new climate

In more detail, the objectives of the project can be summarized as follows:

• To develop accurate spatial models of soil properties relevant to hydropedological processes for the whole forested area of Switzerland using legacy soil data, spatially comprehensive environmental covariates and DSM methods.
• To model the water balance retro- and prospectively on 6000 NFI sites based on the predicted soil properties. To generate maps of drought risks for different regions under current and future climate.
• To characterize forest sites (NaiS-units) ecologically in terms of chemical soil properties and predicted water regime parameters.