Translation - Sonneberg

Summary (Sonneberg)

From Bastian Nordmann

The following study concerns itself with the precipitation drainage characteristics of the soil "periglazialer Fließerden (periglacial solifluction ) underneath a stand of Beech (Fagus sylvatica) and Spruce (Picea abies). On five plots (100m² each) intense rainfall was simulated with 50mm precipitation per hour and the drainage was measured. Not a single plot resulted in Hortonian overland flow (i.e. overland surface runoff). The entire precipitation event immediately infiltrated the highly absorptive surface soil and was then redirected in a laterally orientated organic decomposition horizon which ran perpendicular to the recipient water course. Because of the laterally orientated decomposing biomass the "Braunerden" (brown earth) is characterized by a high lateral discharge velocity. During the winter and spring seasons, when the soil moisture content is very high, the lateral discharge can even be considered intense.

Differences in drainage characteristics as a result of various rooting strategies of spruce, beech and maple could only be rudimentarily ascertained. A possible reason for this is the extremely stony soil (large macropores) and the partially compacted subsoil which lead to minor species specific variability in the results. The clearly sandy and loose subsoil in Röthengrund is highly porous, even at a depth of 1,5 meters could spruce roots be found. Differences in the depth of beech from plot to plot, which could be based upon a delayed reaction, could only be proved limitedly. Findings of concrete discharge characteristics in mixed stands of beech and maple were difficult since these samples had very intense rooting penetration of the subsoil resulting in the most delay and drainage values. An increase in the soil water storage potential from the deep rooting mixed forest species (deciduous trees) seems highly probable. However, the species specific effects are not the same on all plots and are dependent on many pedologic and geologic factors.