Our research group has ample experience in studying microbial communities and specifically nitrifying microorganisms in soils and other environments using molecular tools and isotope tracer techniques. Microbial communities are essential for soil C and N cycling. For example, microbially driven nitrification is an essential step in the nitrogen cycle that converts ammonia to nitrate via nitrite and as such prevents build-up of ammonia. At the same time, it is leaky towards the byproduct N2O and thus contributes to the emission of this potent greenhouse gas (Frame et al., 2017; Lehtovirta-Morley, 2018; Santoro et al., 2019). Nitrifying microorganisms also sustain large populations in soils (up to 1-5%) (Leininger et al., 2006) but there response to aboveground biodiversity changes and increasing abiotic stress is little understood.
The project will assess aspects of global warming and land-use change on the overall microbial community in general and the nitrifier community in particular in high-altitude soils on the Tibetan plateau. Long-term experiments run by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences, at the field stations near Nagchu and Nam Co will serve as a basis. Impacts of yak grazing, warming, and catastrophic snow events on the soil bacterial and fungal community composition will be analyzed by 16S rRNA gene and ITS amplicon sequencing, respectively. Impacts of plant community changes due to global warming (decline of Kobresia pygmea (C.B. Clarke)) and increase in N fertilization will be assessed in respect to changes in the overall microbial community and the nitrifier community in particular. Nitrification rates will be assessed by 15N-ammonium tracer experiments carried out on site. Changes in the microbial and nitrifier community composition will be assessed by next-generation amplicon sequencing of selected target genes (16S rRNA gene, amoA genes).
Cooperation within TransTiP
Changes in plant biodiversity and increasing abiotic stress is of high relevance for ecosystem functioning on the Tibetan plateau. In particular, plant biodiversity is highly affected by the grazing regime, and there is a wealth of literature reporting on the pronounced climate and environmental changes on the plateau. This study will be jointly performed with the group of Prof. Dr. Tsechoe Dorji, who maintains long-term experimental field sites on the Tibetan Plateau and assesses the effect of climate and land-use change on the prevailing plant community. In parallel, there will be a strong exchange with project C4, which will provide deep insights in belowground C and N cycling dynamics. As such, the German and Chinese doctoral researchers will work in a truly holistic and collaborative manner to understand effects of climate change on aboveground and belowground biodiversity and ecosystem functioning.
Prof. Dr. Michael Pester, Leibniz Institute DSMZ
Prof. Dr. Georg Guggenberger, LU Hannover
Prof. Dr. Tsechoe Dorji, ITP-CAS