A standard method for the routine sampling of terrestrial diatom communities for soil quality assessment

Abstract

Terrestrial diatom communities are dynamic, partially unknown and potential bioindicators of the soil ecological quality. Many different sampling methods for soil algae can be found in the literature. However, so far none of them have been tested for their performance with soil diatom communities and given recommendations for obtaining a representative diatom sample for bioindication purposes. The aim of this study was to develop a standardized sampling protocol for terrestrial diatoms and test the spatial variability of the communities to ensure the representativeness of the samples obtained. Sampling was performed in four different sampling sites in the Attert River basin (NW Luxembourg), using metal cylinders (O 5.6 cm) to extract soil cores. Our objective was to determine whether a single cylinder or a mix of several is needed to obtain a representative sample of the community of a certain site. Different statistical analyses (ANOVA, PerMANOVA and Mantel test) have been carried out to assess the reliability of the sampling method and give some recommendations for a routine sampling. Inside each site, no differences were found between single and mixed samples for their species composition or diatom-based quality index values. However, the species richness and diversity had significant differences in the only natural (forest) sampled site. The method here presented has proven to be useful for obtaining representative soil diatom samples and its use is recommended following the advices presented in this work.