Das Projekt "Modelling the relationships and feedbacks between spatial patterns of anecic earthworm populations, related preferential flow pathways and agrochemical transport and degradation in rural catchments" wird vom Umweltbundesamt gefördert und von Technische Universität München, Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt, Fachgebiet Landschaftsökologie, Extraordinat für Landschaftsökologie durchgeführt. Different earthworm ecological types are responsible for macropores of different size and depth, which results in a varying impact on soil hydrology. Within the BIOPORE-project we developed a new approach for modelling water and solute transport which is linked to earthworm distribution models. The main advantage of this approach is that it can be parameterized based on observable field parameters (i.e. macropore density and depth distribution) which can on their turn be mapped at catchment scale using models predicting the spatial distribution of earthworms. We showed that BRT models perform well to predict the spatial distributions of the different earthworm ecological types at the catchment scale. We also showed the strong correlation between earthworms of different ecological types with different macropore sizes and depths. The effectivity of these macropores for water transport was shown to depend more on macropore coatings than on the surrounding matrix soil physical characteristics. Also, we successfully tested the hydrological modelling approach by modelling water and bromide transport at a tile drained field site. Based on a Monte Carlo study, we found system-inherent equifinality, and conclude that even when using physically-based models this equifinality exists in this kind of models. The integral flow data provides only low dimensional information. Additional information clearly reduced the system-inherent equifinality. The experiments underpinned that rapid transport of pesticides is an immanent problem of structured soils. The transport was mainly independent of the pesticide's chemical properties. More interesting is the strong link between hydrological dynamics and pesticide transport. Remobilization of the pesticides was observed during the third of three experiments. Soil water from a depth of 20 - 40 cm seems to be responsible for a large part of the tile drain discharge. This mobilization of soil water leads to a mobilization of stored pesticides and a transport to surface water. Furthermore, we showed that the water that flows in the soil macropores of the Weiherbach catchment is mainly old water and not the irrigated water. This was controlled by the interaction between the macropores and the soil matrix. Large amounts of old water enter the macropore system after a moisture threshold in the soil is exceeded. The combination of our interdisciplinary cross-scale field studies and modelling efforts provides a much deeper understanding of abiotic and biotic processes and patterns determining earthworms, preferential flow as well as infiltration and travel times distribution of solutes.