Soil porosity along a gradient from forest edge to field

This paper analyses two hydrologically relevant soil characteristics-total porosity and the infiltration rate between the forest edge and the abutting crop field (100 m from the edges). The study was conducted in the Central Bohemian region of the Czech Republic in five study transects between March 1999 and September 2000. The experiment was carried out to answer the following main questions: (1) Is there an influence of the distance from the forest edge on dynamic changes in water retention? and (2) Is there a gradient of total porosity in the surface topsoil layers 0-10 cm, 10-20 cm and 20-30 cm of depth? We found a decrease in total porosity in the zone from the forest edge to 10 m inside the crop field. The tendency toward an increase in both characteristics has been observed in zones from 10 m to 2 5 or 50 m. Between 2 5 or 50 and 100 m, the values of both characteristics decrease again. There were no significant differences in the lateral gradient of the two soil characteristics in the three topsoil layers mentioned above. We conclude that soil porosity is increased due to increased density of edaphon. The higher activity of structure-forming soil animals (e.g., earthworms) indicates an "edge effect". The low porosity and infiltration rate in the crop field near the forest edge (0-10 m) are probably caused mainly by higher frequency of agricultural machinery traffic (compacted soil) and also by higher soil moisture (infiltration rate).