Relationships between the properties of Spitsbergen soil, number and biodiversity of rhizosphere microorganisms, and heavy metal concentration in selected plant species

AIMS: The aim of this study was to cross correlate data on physico-chemical parameters of soil with rhizosphere microorganisms and plant species in order to gain more knowledge about formation of soil and development of plants in the face of the changing climate on Spitsbergen and relations between them. METHODS: We investigated physico-chemical parameters of soil samples and the number and biodiversity of microorganisms, bacteria (oligotrophic and copiotrophic), and fungi. Moreover, heavy metal concentrations in 6 species of vascular plants collected in different areas were analysed. RESULTS: The soil samples varied considerably in pH – from acid to alkaline, texture – from sand to loamy sand, and C:N ratio – from very low to high. In the soils, only partial Cd elevation expressed as the geoaccumulation index (Igₑₒ) and the enrichment factor (EF) was detected. In the plants, the most significantly elevated concentrations of heavy metals expressed as Igₑₒ and EF as well as the biological accumulation factor, bioconcentration factor, and translocation factor were detected in Salix polaris, Dryas octopetala, and Draba corymbosa. The high number of bacteria corresponded with an increase in the ecophysiological diversity index and the low colony development index, whereas a reverse relationship was found for fungi. CONCLUSIONS: There was no significant impact of the geochemical properties on the total content of heavy metals in soil. The similar position of Cd and Pb in the order of heavy metal accumulation in the soil and plants was confirmed. TF showed that mainly these two metals were transported efficiently from roots to shoots. In the plants, the metals were distributed depending on the life form and their higher levels were detected in the woody perennials, e.g. S. polaris, D. octopetala, D. corymbosa, than in the herbaceous perennials. Very high numbers of culturable microorganisms were determined, regardless of the soil properties and plant species, which indicated that they were involved in the transformation of compounds containing C, N, and P and in the availability of heavy metals. The microorganisms and plants colonizing Spitsbergen soils showed great plasticity and adaptability to low temperatures and elevated Cd content.