Project C4 aims at addressing major soil functions of the Kobresia grasslands of the Tibetan plateau, i.e., the soils’ capacity as a carbon sink (mitigating climate change) and the associated control of the nitrogen cycling (nutrient provision to plants) and the soil structure (infiltration and storage of water). We want to investigate into the relation of aboveground biodiversity, functional belowground biodiversity and soil functions. Following results from other ecosystem biodiversity experiments, we assume that more biodiverse systems store more organic carbon, are characterized by a closer nitrogen cycling and show a more favorable soil structure, enabling better water infiltration and higher water storage in soil. We further hypothesize that the more biodiverse grasslands with plants of different functional traits have a higher plasticity and resilience against abiotic stress such as drought, heat, or external nitrogen addition.
The study will be based at the TU-ITPCAS Nagchu Integrated Alpine Grassland Ecosystem and Environmental Observation Station. There, we plan to work at the “species removal experiment platform”, where common grassland species with different abundance and functional traits are manually removed since 2013. As a second treatment, nitrogen fertilization was applied to one cohort of the experimental plots. Rainout shelters, mimicking drought, allow for assessment of the response of differently biodiverse grasslands on abiotic stress.
Cooperation within TransTiP
The investigation of both, changes in the aboveground biodiversity and increasing abiotic stress, is of increasing relevance for the Tibetan plateau. The aboveground biodiversity is e.g. highly affected by the grazing regime, and there is a wealth of literature reporting of the drastic climate and environmental change on the plateau.
The studies will be jointly performed by a German and a China funded PhD student working on the same plots and even working with the identical soil samples. There will be also joint supervision by German and Chinese scientists. Tentatively, the following parameters will be investigated:
Supplementary data of the experiments, such as plant biomass, vegetation structure, and gas exchange will be available by collaboration with the Chinese colleagues.
Prof. Dr. Georg Guggenberger, LU Hannover
Prof. Dr. Carlos Sierra, MPI for Biogeochemistry Jena
Prof. Dr. Tsechoe Dorji, ITP-CAS