Buffering role of soil in chemical denudation in mountainous areas affected by windfall events – in light of experimental research

Abstract The important environmental effect of strong mechanical disturbances of the soil cover caused by windfall events can be an increase in chemical weathering and chemical denudation. The aim of the study was to examine how soils with different properties affect the rate of limestone weathering and to what extent do soils buffer ion leaching affecting chemical denudation. A laboratory experiment was performed to answer the questions listed above. Samples taken from typical soils developed on calcareous material in mountainous areas in the temperate climatic zone as well as relatively pure Jurassic limestone were collected for the purpose of the said experiment. Five trials were performed for every combination of soil material and limestone, which yields a total of 90 Eppendorf's conical tubes. Once a week deionized water was poured through each Eppendorf tube (with a hole in the bottom) and then collected. Rock samples and soil samples were analyzed before and after the experiment. The chemical composition of the soil solution (filtrate) was analyzed every five weeks. Our experiment showed that large differences in the degree of chemical weathering of limestone and in the chemical denudation of Ca2+, Mg2+, and K+ at the catchment scale may be expected in soils characterized by different properties. Accelerated chemical weathering of limestone causes Ca2+,Mg2+, and K+ denudation rates to increase, but the studied weathering process was not linearly correlated with denudation rates. The response depends on soil pH, amount of soil organic matter (SOM) in the soil, and the quantity of cations in of the soil exchange complex. Environmental disturbances occurring in mountain areas may lead to the exposure of limestone on the soil surface as a result of events such as windthrow. At least four response scenarios of the disturbed system may be distinguished, depending on soil properties, which are different for (1) soils with thick and very acidic, organic horizons, which is typical for areas under dwarf pine communities, (2) Calcaric Cambisols with thick and slightly acidic organic horizons typical for coniferous and broadleaf forests, (3) Calcaric Cambisols without a thick organic horizon, which is typical for meadows, (4) Rendzic Leptosols, whose soils are typical of calcareous grassland.