Microbial colonisation following explosive volcanic eruptions: reinvigorating research on Krakatau

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.

Ash deposition is economically and socially significant, destroying forest and farmland, presenting lasting hazards of mudflows (lahars) on slopes and clogging waterways. The rate at which volcanic ash fields are stabilized - and the potential to influence this - is thus of considerable interest to local communities and natural resource managers in Indonesia. In the case of Anak Krakatau there is additional interest as the site is a popular tourist destination with the attendant economic benefits that this brings to local communities. There is also the key concern of additional volcanic activity at Anak Krakatau, and the potential for hazardous landslips linked to tsunamis. Therefore, this research will benefit local communities surrounding the volcano in terms of enhanced stability and safety. It is also important for government officials responsible for managing natural resources. Companies and individuals that rely on tourist incomes will also benefit from the research if we achieve a better understanding of the impact of volcanic ash deposition.

The project team has identified a range of specific stakeholders that will have a key interest in both the short- and long-term results of our research. These include the local coastal inhabitants, particularly those involved in the tourist industry, as well as the broader public users of the region (such as national and international tourists). Government agency officials that will have an interest in our work include National Park staff (Anak Krakatau is part of Ujung Kulon National Park in western Java) and members of the National Disaster Management Authority and Centre for Vulcanology and Geological Hazard Mitigation, as well as appropriate local government officials from Serang and Pandeglang regencies. Whilst this research will focus on one particular volcano, the implication of the potential for speeding up succession with more rapid stabilisation of volcanic slopes has a much broader geographical interest, including for much of the heavily populated island of Java in Indonesia as well as potential benefits for locations across the planet that have active volcanoes.