Lux, Johannes

Research interests

My PhD study is part of a collaboration project between China and Germany. My research focuses on the structural and ecological changes of the springtail community along an altitudinal gradient in the Changbai Mountains in China.

Mountainsides all around the world cover a wide range of habitats for organisms of all kind. Varying temperature and moisture with elevation define these habitats. Therefore, researchers use altitudinal gradients as models to predict the influence of climate changes on animal and plant communities. Not only the composition of an animal or plant community may change, even whole food webs may be altered in fundamental ways.

Springtails (Collembola) are an omnipresent group in terrestrial soil systems and serve as prey for a wide range of predators in the soil as well as above the ground. Collembola feed on a wide range of resources; some species even switch diet with changing environmental factors. Thus, the Collembola community may represent changes of the whole soil food web.

I am interested in changes in species composition and food relationships of Collembola along the studied altitudinal gradient and in uncovering the responsible driving factors. To predict ecological changes tracing of food resources within the food web is of eminent importance.

Fatty acids stored in an organism provide information on the basal resources the animals rely on. Some fatty acids are synthesized by certain organism groups and directly incorporated into the body of consumers, which are not able to synthesize them by their own. I use neutral lipid fatty acids (NLFA) to detect changes in trophic niches and trophic relationships of Collembola along the studied altitudinal gradient. To better understand energy fluxes, I also investigate phospholipid fatty acids (PLFA) and use them to characterize the microbial community in the litter and soil at the different altitudes.

Furthermore, I use 15N, a stable isotope of nitrogen, to reveal changes in the trophic position of Collembola within the food web. 15N occurring naturally, but in smaller amounts compared to its lighter counterpart. Because of its higher mass, 15N is discriminated in metabolic processes and thus, accumulates inside an organism. If a predator consumes prey, its 15N signature is increased, resulting in the enrichment in 15N at higher trophic levels.

Another stable isotope I use for food-web analyses is 13C. This heavier isotope of carbon is less discriminated by metabolic processes. Thereby, it can be used to trace basal resources of food webs.

Furthermore, I will use compound-specific isotope analysis to investigate the relative contribution of resources to the diet of Collembola communities and their changes with altitude.

The project is funded by the DFG in the framework of a collaborative project between the University of Göttingen, Germany, and the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Chanchun, China.