The aftermath of explosive volcanism is ecologically important in Indonesia but difficult to study because of its unpredictability. In this proposal, we propose to monitor ecosystem recovery after volcanic eruptions with a specific focus on soil micro-organisms and how they can mediate initial soil development in fresh ash deposits. Whilst previous studies have examined microbial communities in 'young' volcanic environments, the age of these deposits was generally in the order of years, thereby missing the key earliest stages of succession during which microbes start to modify the initial edaphic environment. Major volcanic activity at Anak Krakatau, an iconic island volcano in Indonesia, in December 2018 led to a complete reconfiguration of the island and the rare opportunity to study microbial recolonisation and the importance of microbes in ecosystem recovery. In this urgency project, we will sample ash/soils from Anak Krakatau within a few months of the eruption producing a novel dataset. Microbial diversity will be compared with that in the spore-rain to assess if there are constraints to microbial colonisation. We will also set up a series of experiments whereby we inoculate ash/soil to determine how the colonisation of microbes can influence carbon and nutrient accumulation in the ash substrate and the growth of pioneer plant species, and conversely how constraints to colonisation might impede it. Understanding the development of soils over volcanic ash is important because they are very fertile and support high population densities as well as sequestering large amounts of carbon over decadal timescales.