Nitrogen and ash elements content in sub-horizons of forest floor

Abstract

Nitrogen (N) and ash elements contents of forest floor (FF) depend on the fractional and chemical composition of falling litter. The elemental content in FF may be influenced as well by originated from the epipedon mineral particles due to soil fauna mixing activity. In actual work the contents (concentration and stocks) of N and ash elements were analysed in relation to phytogenic FF. In relation to total FF, the FF thickness, acidity, base saturation stage and C:N ratio as general characteristics were studied. The concentrations and amounts of N and ash elements of FF were studied on Gleyic Albic Fragic Glossic Retisols (group I), on Gleyic Albic Podzols (II) and on Ortsteinic Histic Podzols (III). The FF chemical parameters were researched in forest ecosystems with premature and mature (i.e. stabilized) forest stands. The dividing of FF into sub-horizons was possible only on soils with low soil faunal activity. The FF and its sub-horizons (OL, OF, OH) were sampled with a metallic frame (25×40cm). In the field conditions, the FF thickness (cm) and mass superficial density (gm−2) at field moisture content were determined. In the laboratory, the total and phytogenic FF dry mass superficial densities (Mgha−1) and their elemental contents (concentration – gkg−1 and amounts – kgha−1) were calculated. Content of N in FF samples was determined by Kjeldahl; content of K with flame-photometer; P by colorimetric method; Ca and Mg by complexometric titration with trilon B (using flame-photometer); Fe and Al colorimetrically, whereas in the case of Fe the sulfosalicylic acid and for Al the aluminon was used; the Si and remains were determined with weighing method. The soils of groups’ I and II are well drained aeromorphic, but group III hydromorphic. By WRB the soils of group I are Retisols, but soils of two rest groups - Podzols. The soils of group I have been formed on loamy sand under-layered by loam, but the texture of groups II and III soils is sand. By the humus covers the soils of group I may be classified as fresh and moist moder, of group II as fresh and moist mor and of III as wet and peaty mor. On soils of groups II and III only the pine forest, but on soils of group I as well the spruce forest are presented. In all three soil groups the sequence of chemical elemental concentration in OL horizon (as falling litter) was: N>Ca>Si>Mg>K= Fe=P>Al. In the course of further FF developments, the concentrations Si, Al and N are increased in considerable extent. Practically to the same level persist the concentrations of K, P and Mg. At the end of throughout flow of FF this sequence was: Si>N>Ca>Al>Fe>Mg>K=P. The greatest amounts of all studied elements were observed in the FF of soils’ group III on which the humus cover of wet and peaty mor type has been formed. The formation of this type of humus cover indicates the stagnation of elemental cycling between plant cover and soil cover.