Between 2011 and 2015, soil samples at 0 to 20 cm soil depth were collected and processed from the almost 1,200 sites of the Swiss Biodiversity Monitoring BDM at which the indicator Z9 «Species Diversity in Habitats» is assessed (Figure). The combination of plant physiological assessments with soil sampling at each site fills a significant gap in the biodiversity monitoring programme.
On the one hand, surveys of vascular plants, mosses and molluscs can now directly be related to soil parameters such as pH, carbon content, bulk density, etc. and interpreted accordingly. The synchronised sampling of various environmental compartments provides high synergetic benefits at relatively low extra costs. The results represent a mutual added value for the interpretation of the individual data.
On the other hand, the joint project NABO-BDM yields for the first time a uniform nationwide Swiss collection of soil samples. This collection is characterised by a large sample size and an adequate representation of the area, thus offering enormous potential for national and regional assessments. The archived fine soil samples and the separately assessed coarse soil material (gravel and rocks) are available for further analyses to address various issues.