Does ecosystem diversity affect soil hydraulic properties? : investigation of biotic and abiotic factors on infiltration capacity in a grassland biodiversity experiment
The present thesis aims to evaluate the relationships between soil hydraulic properties and earthworms, plant community, soil structural parameters, soil texture, and soil moisture in the frame of a long-term grassland biodiversity experiment, the so called Jena Experiment. Hydraulic properties such as infiltration capacity play an important role in soil erosion, run-off and water availability to plants for the prediction and management of ecosystems. Global change has led to an increase in flood frequency events caused by heavy rainfalls. For sustainable soil management (reducing soil erosion and run-off) as well as for improving hydrological models, it is important to know which factors influence infiltration. Generally, soil texture considered one of the most important factors for explaining hydraulic properties, but other influences like bulk density or soil fauna have also been recognized. However, because infiltration is a complex process, a multitude of interrelated processes affects infiltration capacity, and therefore investigations yield controversial results regarding specific factors. In this thesis, I distinguish between abiotic soil factors (texture), which are constant in time, and biotic factors (soil fauna, ecosystem structure), which change dynamically depending on environmental factors. The majority of previous experiments has focused on one or two selected factors influencing hydraulic properties, and do not account for interaction. The aim of this thesis was to identify the most important drivers for the infiltration capacity in a grassland experiment (The Jena Experiment), while explicitly taking into account interaction.