The focus of his research is to understand the impact of climate change on ecosystems. In Giessen he is leading a Free Air Carbon Dioxide Enrichment study on grasslands, which is one of the longest running field climate manipulation studies worldwide, running for 20 years. To understand the processes, he has developed a number of nuclear methods to quantify the rates of elemental transformations in the soil (N cycle, P cycle, C cycle) and identify the processes leading to greenhouse emissions. Since 2014, he has been working as an expert for the IAEA, specifically in training methods to quantify greenhouse gas emissions.