B02 - Impact of rainforest transformation on phylogenetic and functional diversity of soil prokaryotic communities in Sumatra (Indonesia)

Prokaryotes are the most abundant and diverse group of microorganisms in soil. Soil microorganisms mediate nearly all biogeochemical cycles in terrestrial ecosystems and are responsible for most nutrient transformations in soil, thereby, influencing the aboveground plant diversity and productivity. In this subproject, the impact of lowland rainforest transformation on diversity and ecosystem function of soil prokaryotic communities is investigated. To identify changes in indigenous gene- and taxon-specific patterns and key metabolic functions accompanying rainforest transformation, comparative phylogenetic and functional profiling of soil microbial communities are performed. So far, we compared soil prokaryotic (Bacteria and Archaea) community composition, diversity and function of the four systems by culture-independent DNA-based metagenomic (entire community level) and RNA-based metatranscriptomic (active community level) approaches at all core sites. The analysis of the prokaryotic communities within the different transformation systems revealed the main bacterial and archaeal groups, ecosystem functions of these groups, and differences between the systems. The diversity analysis of the prokaryotic communities showed that prokaryotic communities, against expectations, are more diverse in plantations than in rainforest soils. The higher diversity in plantation could be partially related to different soil attributes such as P content (Bacteria) and N content (Archaea). To analyse this in detail the impact of management regime and treatment-induced changes (e.g., pesticide treatment) and biodiversity enrichment in plantations on microbial diversity and function will be investigated in the framework of the oil palm management and planting experiments. In addition, analysis of temporal changes of soil microbial community structure and function along the transformation systems and in riparian sites will be analysed and compared. We hypothesize that the increase of prokaryotic diversity during rainforest transformation to plantations has a negative effect on fungal diversity and function. The feasibility of partial replacement of eukaryotic soil functions and nutrient transformations by prokaryotic organisms is studied. In addition, interaction networks between the different prokaryotic functional groups and between prokaryotic groups and other soil organisms in the different systems will be established.