Vesicular–arbuscular mycorrizae for dating multiple paleosols and carbon loss rate determination

A promising technique for dating paleosols is reported based on radiocarbon (14C) dating of asexual spores from vesicular–arbuscular mycorrizae (VAM). The soils are dispersed in water and some 6000–8000 spores separated by hand picking under a low power microscope. The dried spores are then dated by accelerator mass spectroscopy (AMS). A chronosequense of closely superimposed paleosols from an arctic/alpine meadow soil, northern Sweden, was dated and the long-term (i.e., over a millennium time-span) organic carbon loss rate determined. A very low carbon loss rate was obtained, 4.7×10−4±9.2×10−5 year−1. It is argued that this approach is likely to give a better estimate for long-term loss than litter-bag studies covering a couple of decades.