Community structure and guild patterns of soil decomposers

PhD student

Jingzhong Lu (Logos)

Research Outline

Anthropogenetic global warming is creating new challenges for forest management in many parts of the world. One vital aspect is the choice of tree species and whether to cultivate monospecific or mixed timber plantations. To better understand effects of forest types on ecosystem functioning in the framework of the RTG 2300, I have focused on soil decomposers, including soil microbial and microarthropod communities (SP5-1).

I first investigated the structure and functioning of microbial communities using microbial respiration and phospholipid fatty acid analyses. Coniferous forests, especially pure Douglas fir, adversely affected soil microbial communities and compromised their functioning in unfavorable environments. These findings, published in Lu and Scheu (2021), call for caution when deciding whether to plant pure Douglas fir under less-favorable site conditions and contribute to a context-wise understanding of tree-soil interactions.

I next quantified the abundance and diversity of soil collembolans and oribatid mites. Species composition of oribatid mites, but not of collembolans, sensitively responded to forest type, differing most between Douglas-fir and European-beech forests. Further, the abundance of both euedaphic collembolans and predatory oribatid mites were lower in pure Douglas fir forests than in European beech, presumably due to lower provisioning of root-associated resources in Douglas-fir forests.

To further understand the intraspecific variation in food resources of oribatid mites, stable isotope ratios of 15N/14N and 13C/12C was quantified for 40 oribatid species in both litter and soil. Oribatid species occupy virtually identical trophic positions irrespective of the soil depth or forest types they were recovered. These findings, preprinted in Lu et al. (2021), suggest that low intraspecific variability of oribatid species may facilitate their niche differentiation and species co-existence.

Overall, mixed forests maintained soil microbial and microarthropod communities close to the state of native European-beech forests and mitigate the adverse impact of coniferous forests. As a whole, these results contribute to a better understanding of the structure and resource utilization of soil decomposer communities and serve as a stepping stone for the next phase of the research training group.

Principal Investigator / Supervisor

Prof. Dr. Stefan Scheu, Animal Ecology Group, J. F. Blumenbach Institute for Zoology and Anthropology, Faculty of Biology and Psychology