Modeling interactions of water fluxes with species and structural diversity in temperate forests

Abstract

The ecosystem functions of temperate forests are expected to be severely affected by future climate change, in particular by hydro-meteorological extremes (heavy precipitation, droughts and heat waves), which will increase in frequency, duration, extent and magnitude. Previous studies have shown that both structural and tree species diversity can act as a buffer against the effects of climate extremes. To better understand the influence of structural and tree species diversity, we use two models to analyse the influence of species and structural diversity on hydrological dynamics during recent drought events. The well-equipped experimental plots are located in central Germany and represent typical forests of the region. One of the models is the individual forest gap model FORMIND. Using a newly developed technique, it allowed us to analyse local heterogeneous patterns of carbon and water cycling, runoff and water stress and their relationship to structural and species diversity on a 2-metre scale. The second model is mHM, a mesoscale hydrological model with a parameterisation of the catchment area in which the field plots are located. We also used a coupled version of these two models for the analysis. Our analyses show that only about half of the modelled water dynamics are driven by meteorological conditions and the LAI. The other half is driven about equally by functional and structural diversity. This new two-model and interdisciplinary workflow allows us to consider various soil-plant-atmosphere interactions in drought disturbed ecohydrological systems.