Data from: The rise and fall of arbuscular mycorrhizal fungal diversity during ecosystem retrogression

Ecosystem retrogression following long-term pedogenesis is attributed to
phosphorus (P) limitation of primary productivity. Arbuscular mycorrhizal
fungi (AMF) enhance P acquisition for most terrestrial plants, but it has
been suggested that this strategy becomes less effective in strongly
weathered soils with extremely low P availability. Using next generation
sequencing of the large subunit ribosomal RNA gene in roots and soil, we
compared the composition and diversity of AMF communities in three
contrasting stages of a retrogressive >2-million-year dune
chronosequence in a global biodiversity hotspot. This chronosequence shows
a ~60-fold decline in total soil P concentration, with the oldest stage
representing some of the most severely P-impoverished soils found in any
terrestrial ecosystem. The richness of AMF operational taxonomic units was
low on young (1000's of years), moderately P-rich soils, greatest on
relatively old (~120 000 years) low-P soils, and low again on the oldest
(>2 000 000 years) soils that were lowest in P availability. A
similar decline in AMF phylogenetic diversity on the oldest soils
occurred, despite invariant host plant diversity and only small declines
in host cover along the chronosequence. Differences in AMF community
composition were greatest between the youngest and the two oldest soils,
and this was best explained by differences in soil P concentrations. Our
results point to a threshold in soil P availability during ecosystem
regression below which AMF diversity declines, suggesting environmental
filtering of AMF insufficiently adapted to extremely low P availability.