Stand species composition as a key factor determining the amount of
polycyclic aromatic hydrocarbons (PAHs) in forest soils
Abstract
The aim of the study was to determine the effect of stand species
composition on PAHs accumulation. The study covered the soils of the
stands of the Rybnik Forest District, which are under the influence of
one of the highest deposition of industrial emissions in Europe. Pine,
pine-oak and oak stands growing in the same soil conditions were
selected for the study. Samples for further analyses were collected from
the organic horizon, from the humus mineral horizon and from the mineral
horizon. Organic C content, N content, pH, alkaline cation content, as
well as microbiological biomass of C, N, extracellular and intracellular
enzyme activity were determined in the soil samples. PAH content was
determined in the soil samples. Additionally, the soil organic matter
fractions were determined: free light fraction (fLF), occluded light
fraction (oLF) and mineral associated fraction (MAF). Pine stand soils
were characterized by the highest average PAHs content. The oak stand
soils were characterized by the lowest PAHs accumulation and high
enzymatic activity. The study confirms the important role of the stand
species composition in shaping the quality and quantity of SOM and soil
acidification, which in turn is reflected in microbial activity and PAHs
accumulation in forest soils. PAHs accumulation in forest soils is
related to the fractional composition of SOM, which is the effect of the
influence of species composition through the supplied aboveground and
belowground biomass. A strong correlation between the PAH content and C
content of the light soil fraction of OM was noted.