The palaeoecological value of Diporotheca rhizophila ascospores (Diporothecaceae, Ascomycota) found in Holocene sediments from Lake Nussbaumersee, Switzerland

Lake Nussbaumersee, a medium-sized lake SW of Lake Constance (Switzerland) and well known for its Neolithic and Bronze Age pile-dwelling settlements, provides invaluable insights into the possible interpretation of Diporotheca rhizophila ascospores (Diporothecaceae, Ascomycota) in palaeoecological studies. Calcareous gyttja sediments from a 7500 yrs old stratigraphy were analysed palynologically, resulting in statistical correlations of Diporotheca spores with pollen and non-pollen palynomorphs (NPPs). Positive correlation existed with arboreal taxa such as Corylus avellana and Acer, herb taxa such as Allium, and aquatic taxa such as Anabaena (Cyanobacteria) and Filinia eggs (Rotifera). Negative statistical correlation was shown between Diporotheca and the arboreal taxa Quercus and Betula, Poaceae and Cyperaceae, and the fern Pteridium aquilinum. These results suggest that ecological indicator values for the root parasite D. rhizophila may not only be closely related to the autecology of its common host Solanum, but that D. rhizophila may generally be an indicator of major soil disturbance and extensive soil erosion due to the impact of agricultural activities by prehistorical people, as well as due to livestock trampling of wetlands and lake shore ecosystems.

► The paper deals with the NPP Diporotheca (HdV-143) from Holocene lake sediments.
► The use of Diporotheca as prehistorical environmental indicator is shown.
► The ecological indicator value of Diporotheca is related to the autecology of Solanum.
► Diporotheca can indicate soil erosion, often related to human activities.
► The question is raised whether other host species for Diporotheca must be considered.