Fatty acid patterns of soil decomposers and predators as affected by plant species richness

by German Augusto Murrieta Morey
Master thesis
Date of Examination:2013-02-05
Date of issue:2018-05-24
Advisor:Prof. Dr. Stefan Scheu
Referee:Prof. Dr. Stefan Scheu
Referee:PD Dr. Mark Maraun
Persistent Address: http://dx.doi.org/10.53846/goediss-6882

 

 

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Abstract

English

Relationships between organisms in the soil are very important to control the equilibrium of an ecosystem. Many factors and conditions play a crucial role for the development and functioning of decomposers and predators, i.e., plant species richness have an effect on soil biota, increasing the diversity of organisms. During recent years, fatty acid (FA) analysis has become a very useful tool to reveal food webs and feeding preferences of different organisms. The present study took place in the framework of the “Jena Experiment”, located in the floodplain of the Saale River near the city of Jena, Thuringia, Germany. Animal samples were collected from 76 plots with different plant diversity levels: 1, 2, 4, 8 and 16 and different functional groups: grasses, legumes, small herbs and tall herbs. Soil animals were extracted by heat, collected in diluted glycerol and transferred into 70% ethanol for storage under room temperature. The most abundant decomposers were: Allolobophora chlorotica and Aporrectodea caliginosa, while the most abundant predators were: Geophilus flavus, Lithobius microps, Amara aenea and Aleocharinae beetles. Neutral lipid fatty acids (NLFAs) were used to test if plant species richness affect the presence and amount of FAs in the animals and to expose their feeding habitats and preferences in the field. Results indicated that plant species richness has no effect on FA patterns in decomposers and predators, being the presence and amount of FAs only influenced by the species itself. Although, more species and more individuals were found in plots with more plant species richness, the results were not statistically significant. The presence of bacteria, fungi and plant markers in the FA composition of the decomposers and predators suggests trophic transfer and incorporation of intact soil microbial FAs into the FA profiles of the animals, proving the effectiveness of this method not only for laboratory experiments but also for investigations in the field. The plant marker 18:1ω9 was the most abundant FA in all animals, suggesting plant and plant feeding prey species preferences.
Keywords: Fatty acids; decomposers; predators; markers; species richness
 
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