Data for: Assessing above and belowground recovery from ammonium sulphate addition and wildfire in a lowland heath: mycorrhizal fungi as potential indicators.

Atmospheric pollution containing soil-nitrifying ammonium sulphate
((NH4)2SO4) affects semi-natural ecosystems worldwide. Long-term additions
of (NH4)2SO4 to nitrogen(N)-limited habitats, including heathlands,
increase climate stress affecting recovery from wildfires. Although
heathland vegetation largely depends on ericoid mycorrhizal fungi (ErM) to
access soil N, we lack a detailed understanding of how prolonged exposure
to (NH4)2SO4 may alter ErM community composition and host plants’ reliance
on fungal partners following wildfire and affect recovery. Simulation of
atmospheric pollution ((NH4)2SO4) occurred bi-weekly for 5 years after a
2006 wildfire in a UK heathland. Ten years after treatments ceased, we
measured vegetation structure, lichen and lichen photobiont composition,
soil characteristics, ErM colonisation, ErM diversity in roots and soil,
and assessed ErM potential as novel recovery indicators. Heather height
and density, and moss groundcover, were greater in
N-enriched plots. Lichen community indices showed significant treatment
effects but without differences in photobionts. Soil pH and Mg were
significantly lower in treated plots while soil cation exchange capacity
was significantly higher. There were no detectable differences in ErM
composition and keystone ErM taxa between control and treated plots. Soil
carbon stock measures were variable. Our results indicate atmospheric
pollution following fire can have significant lingering effects above- and
belowground. ErM diversity and root colonization were not assessed in the
original N-addition experiment; we advocate for their inclusion in future
studies as an integral part of the recovery assessment toolkit. We show
that mycorrhizal fungi diversity is a viable ecological tool and summarise
key steps for ErM identification.