Title: Kritisk belastning av aciditet för skogsmark i norra Tjeckien
Abstract: Forest decline is an increasing problem in Europe. Black Triangle area, situated in mountainous region where borders of Germany, Czech Republic and Poland meet, is one of worst damaged areas. The reasons for forest dieback are not fully understood, but soil acidification caused by burning of sulphur rich coal in region is considered a major cause.
To reduce soil acidification emissions of acidifying compounds must decrease. For this to be possible decision makers must have some kind of concrete information about acidification status in different regions. This is background of construction of concept load of acidity, which is highest deposition of acidifying compounds that does not cause long-term harmful effects on specified elements of an ecosystem. By comparing critical load with acid deposition, areas where critical load is exceeded can be identified. Critical load maps give useful information when it comes to decisions to forest soils in Czech part of the Black Triangle, have been calculated using Simple Mass Balance model (SMB). The SMB model is based on a long-term steady state approach using long-term sources and sinks of acidity. The main source of acidity is acid deposition, and one of dominating sinks is weathering of base cations in soil. The harmful effects on forest ecosystem can be linked to acid deposition by specifying a critical limit on molar ratio between concentrations of base cations [BC] and aluminium ions [Al] in soil solution. The critical limit used in this study is [BC]/[Al]=1.0. The critical load is deposition which ensures that [BC]/[Al] ratio does not decrease below 1.0 in a long-term perspective.
The critical load was exceeded in 76% of forest area according to model calculations, using deposition data from 1992. The highest exceedances were found in mountains along Czech border, northwest of Prague. Non-exceedance areas were found in regions with rich soils.
The exceedance of critical load was compared with forest damages in 13 regions. The coverage fraction of forest with severe damages, expressed as needle loss, in different regions were plotted against mean exceedance, maximum exceedance and median of exceedance in regions. The same type of analysis was performed using coverage fraction of forest damage related c1earcuts. Relationships were found between calculated exceedance and forest damage. This was most obvious when maximum value of exceedance was used. The magnitude of forest damage degree on 51 permanent plots was compared with exceedance, but no clear relations were found.
Many parameters are included in SMB model, and since all parameters inherit uncertainties, uncertainties in result can be expected to be substantial. Improvements can be made continuously, when new data, with less uncertainties, become available. Of highest priority are improvements of weathering data and deposition data. However, although large uncertainties are accounted for in calculations, trends are considered to be reliable.
Publication Year: 1997
Publication Date: 1997-01-01
Language: en
Type: article
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Cited By Count: 29
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