Sodium in precipitation in a beech forest ecosystem in the kremnické vrchy mts (Western Carpathians)

We present data on sodium amounts reaching the forest soil surface at the Beech Ecological Experimental Site Kremnické vrchy Mts (Western Carpathians). Sodium concentration and deposition were determined in precipitation and throughfall sampled from study plots. The mean annual sodium concentrations obtained on the two plots (CC - clear cut, C - control) were 0.16 (CC ) and 0.19 mg l⁻¹ (C). The values were the lowest among the base cations in precipitation. The trends in spring and annual concentrations were similar, in the 10th year after the intervention, identical. The possible cause is interception of precipitation in the stand and the ions tendency to absorb by beech leaf tissues. This may cause interception of precipitation in the stand and the tendency of beech leaf tissue to absorb sodium ions. Also, the mechanism driving the ion exchange between K⁺ and Na⁺ may cause lower sodium content in throughfall. On both plots, the sodium concentration in spring was somewhat higher than in other seasons of the other year: 0.04-0.42 (CC ) and 0.07-0.76 mg l⁻¹ (C). The trends of spring sodium concentration and deposition on C were decreasing. Plot CC in spring was the only case showing an increasing trend. The spring trends evidently reflected the fact that 10-12 years after the cutting intervention, natural regeneration and growth of beech stand occurred on both the plots. Moreover, the mean winter and summer sodium deposition on both plots was low (0.02 kg), showing a decreasing trend. The autumnal deposition was 0.5 kg (CC ) and 0.3 kg ha⁻¹ (C). The total annual sodium amount reaching the forest soil surface was lower on C (0.9 kg) than on CC (1.2 kg ha⁻¹ year⁻¹). The crown impact coefficient (CIC),the deposition ratio between the plots C:CC , values were 0.6 (spring, autumn), 1.0 (winter, summer) and 0.8 (year). There was no manifested presence of sodium sources of either natural or anthropogenic origin. All the obtained values are low and may be considered as background. They indicate that the Beech Experimental Ecological Site is ecologically clean.