Data di Pubblicazione:
2006
Abstract:
Podzols often occur in association with organic soils along sequences governed by relief, with peats in depressions and
podzols on slopes. The formation of bogs has also been described as a soil-induced process: the formation of cemented pans,
impermeable to water, in highly developed podzols, enhanced the accumulation of organic matter and slowed down its
decomposition. Humans may interfere with soil development, enhancing acidification and thus the eluvial phase of
podzolisation, as it may be in the case of acid precipitation or of the plantation of conifers. The aim of this work was to study the
transition between Spodosols and Histosols, in the Krkonosˇe National Park (CZ), where spruce has substituted the natural
vegetation and acid precipitation has damaged several areas of the park. The soils were studied at two sites: one site is relatively
preserved and soils (Spodosols and Inceptisols) develop on a steep slope. At the other site, a gently undulating mountain
summit, Spodosols are associated to Histosols and the forest decline is more severe. Three Spodosols (Humic Haplocryod,
Typic Cryaquod, Placic Cryaquod) and a Histosol were selected at the second site, and the soil properties and organic matter
dynamics were compared to those of a Typic Haplocryod sampled at the first site. Profile morphology and chemical analyses
indicated that podzolisation has been more intense at the second site, probably because of the differences in relief and in the
amount of water available for pedogenic processes: a high accumulation of organic matter and thick Bhs horizons were the most
striking differences, together with depletion in Fe from eluvial horizons. Moreover a trend in the chemical indicators of
podzolisation was appreciated among the profiles sampled at the second site. The analyses of organic matter and humic
substances indicated that, in Bs horizons, the organic matter characteristics were very similar in the two sites, but in the eluvial
and organic horizons marked differences appeared. At the first site, the fulvic acids in the E horizons were small and oxidised,
similar therefore to those found in the Bhs horizons, whereas at the second site fulvic acids became bigger, more aliphatic and
less oxidised and were therefore less prone to migration. Some of these properties of organic matter were linked to soil water
regime, others to the shift in vegetation from forest to grass cover and seemed therefore to be related to the soil evolution itself,
being podzolisation in this sense a self-limiting process. Acid precipitation may however have played a role in the change of
size of fulvic acids, which were very rich in sulphur, through C–S linkages. The complex interaction between natural and
anthropogenic factors seemed to have decreased the ability of organic matter to migrate, enhancing the formation of Histosols.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
BONIFACIO E; SANTONI S; CELI L; ZANINI E
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