engleski

Investigating Dynamics of Soil Acidification: Application of the biogeochemical model SAFE to two sites in the Republic of Croatia

Air pollution and the related soil acidification can cause extensive damage to forested ecosystems. So far, pollution abatement strategies were based on the concept of critical load, the critical load being defined as a quantitative estimate of the load of acidity that an ecosystem can withstand in the long run.The critical load and the related steady-state models do not, however, offer any information on the temporal evolution of the soil chemical variables. In order to investigate the dynamics of soil chemistry and predict the recovery rates after a drop in the acid load, dynamic models have to be applied. In this study dynamics of soil acidification for two sites in the Republic of Croatia have been assessed with the SAFE (Simulated Acidification in Forested Ecosystems) model. SAFE is a dynamic biogeochemical model that calculates the temporal evolution of soil chemistry on the basis of atmospheric deposition and data on soil properties and nutrient cycling. The indicators of soil acidification investigated with SAFE were the pH of the soil solution, the base saturation and the molar ratio of base cations and aluminum (Mg+Ca+K/Al) in the soil solution. Simulation results show that the soil at the sites did acidify and that base saturation dropped significantly from preindustrial levels. However, the base cations to aluminum molar ratio did not exceed the critical limit (1) at any point in time throughout the simulation period at both simulated sites. It can be concluded that the forest stand at the two sites modelled with SAFE did not nor will experience any adverse effects. Due to the lack of site-specific data the results presented in this paper should be regarded only as tentative. This modelling exercise pointed out that the current data set in Croatia would have to be complemented with data on cation exchange capacity and base saturation if dynamics of soil acidification are going to be assessed regionally.

acidification; soil; SAFE; Croatia

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