Humic fractions as indicators of soil organic matter responses to clear-cutting in the mountain and lowland conditions of south-western Poland
Elżbieta Jamroz, Maria Jerzykiewicz
Land Degradation & Development
Ministerial score = 200.0
JIF Impact Factor (2020) = 4.977(Q1)
Clear-cutting means forest removing (stem only) and is the most common type of forest harvesting but undoubtedly has a negative impact on the C budget in soils. This work aimed to describe responses of soil organic matter (SOM) in the mixed coniferous forest to the removing of trees under temperate climate conditions of lowland and mountain regions in south-western Poland. Investigated soils were described as Brunic Arenosols derived from sand with the average content of total organic carbon (TOC) in the Oa horizons 244 g·kg-1, in the lowland and Dystric Cambisols derived from gneiss with the average content of TOC in the Oa horizons 309 g·kg-1, in the mountain regions. Analysed soils were very acidic in the both regions (pH 2.7–3.5 in the topsoil). In the experiment two replicated soil profiles were located on each site, both after clear-cutting and without any harvesting. Humic fraction was isolated from Oa and A horizons, differences between investigated objects were checked with a significance P <0.05, (n=16). Using instrumental analysis, like EPR, 1H NMR and FTIR spectroscopy applied to isolated humic fractions, it has been found that clear-cutting alters C cycling and accelerates decomposition in the forest floor leading to loss of humic fractions in the investigated soils. In the mountain forests the more labile, low-molecular weight fulvic fraction decreased as the effect of harvesting practice by 30% in Oa horizon and by 54% in A horizon. Analysis of stable radicals by EPR showed a decrease in radical concentration observed for humic acids (HA) from mountain clear-cut areas compare to the undisturbed forest. Results presented in this paper have proved less aliphatic character of HA molecules from the lowlands, compared to the mountain forest as the effect of clear-cutting. Changes in plant cover observed as a consequence of deforestation lead to the decrease in concentration of humic fractions with different solubility properties.
DOI:10.1002/ldr.4158
