Microbial community structure and function were assessed in the organic horizon and upper mineral soil across a ~4000 year dune-based soil chronosequence at Big Bay, New Zealand, where the proportional contribution of organic soil in the profile increased with time. Structure of bacterial, fungal and non-specific acid and alkaline phosphatase-harbouring communities was examined in both soil horizons across 3 dunes using amplicon sequencing, network analysis and qPCR.