Dr. Christoph Digel

Research interests:


Complex food webs provide an integrated understanding of the diversity, organization and functioning of natural communities. They depict energy flows from producer (e.g. photoautotroph) and other basal species to higher trophic levels.

Body masses are important indicators for energy which is transfered through the food web via the links which represent the feeding interactions between the species. For the single organism its body mass is among the most important traits determining many physiological and ecological characteristics e.g. metabolic rates, ingestion rates, interaction strenghts with other species and locomotion speed.

The degree of a species describes its number of links (i.e. feeding interactions) to other species. It can be viewed seperately as linkedness (total number of feeding interactions), vulnerability (number of links to predator species) and generality (number of links to prey species). I am particularly interested in allometric degree distributions of natural food webs. These describe how linkedness, generality and vulnerability scale with species body masses irrespective of their taxonomy or other traits. Allometric degree distributions seem to be a general feature of natural food webs across different ecosystems.

However, good documented soil food webs are scarce and knowledge of the body masses and degree distributions would be crucial since soil food webs provide many ecosystem functions important for the aboveground communities. As an example energy produced by plants and aboveground fauna is transferred back to the system by detritivores, bacteria and fungi in the soil.

Currently I develop a set of forest soil food webs in collaboration with researchers from the biodiversity exploratories. My next goal is to compare soil foods webs with food webs from other ecosystem types to find systemic differences and similarities. I want to develop a food web model which accounts for the specialties of the soil habitat to provide a better understanding of the often neglected soil communities which are of critical importance for the aboveground ecosystem functioning.


Publications


Digel, C., Curtsdotter, A., Riede, J., Klarner, B. & Brose, U. (2014): Unravelling the complex structure of forest soil food webs: higher omnivory and more trophic levels. Oikos, 123(10): 1157-1172, doi: 10.1111/oik.00865


Ott, D., Digel, C., Rall,B.C., Maraun, M., Scheu, S. & Brose, U. (2014): Unifying elemental stoichiometry and metabolic theory. Ecology Letters, 17(10): 1247-1256, doi: 10.1111/ele.12330


Ott, D., Digel, C., Klarner, B., Maraun, M., Pollierer, M., Rall, B.C., Scheu, S., Seelig, G. & Brose, U. (2014): Litter elemental stoichiometry and biomass densities of forest soil invertebrates. Oikos, 123(10): 1212-1223, doi: 10.1111/oik.01670


Ehnes R. B., Pollierer M. M., Erdmann G., Klarner B., Eitzinger B., Digel C., Ott D., Maraun M., Scheu S., Brose U.: Lack of energetic equivalence in forest soil invertebrates . Ecology (accepted)



Digel C, Riede J. O. and Brose U: Body sizes, cumulative and allometric degree distributions across natural food webs, Oikos, in press; DOI: 10.1111/j.1600-0706.2010.18862.x



Poster presentations



Digel C, Riede J. O. and Brose U: Allometric degree distributions across natural food webs, BES Annual Meeting 2010, 7-9 September, University of Leeds, UK
Digel C, Riede J. O. and Brose U: Allometric degree distributions across natural food webs, Multitrophic Interactions Workshop 2010, 25-26 March, Georg-August University Göttingen, Germany