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Ecological groups of Collembola in agroecosystems as affected by farm-based management practices

dc.contributor.advisorScheu, Stefan Prof. Dr.
dc.contributor.authorHanisch, Jörg
dc.format.extent109 Seitende
dc.titleEcological groups of Collembola in agroecosystems as affected by farm-based management practicesde
dc.contributor.refereeScheu, Stefan Prof. Dr.
dc.description.abstractengPresent day agriculture is identified as a main threat to biodiversity. At the same time, the productivity of agricultural systems is relying on ecosystem services provided by biota. In order to conserve critical ecosystem services for future generations preserving the functions of the soil is one main goal of sustainable agriculture. Nevertheless, the impact of management practices on soil biota providing critical ecosystem services remains ambiguous. The high level of complexity in combination with limited taxonomic knowledge and the opaqueness of the soil hampers general conclusions. To develop sustainable management practices a better understanding of how farm-based management practices shape soil biota communities is needed. Thereby, trait based approaches can be used to increase mechanistic understanding while at the same time circumvent time consuming species identification. In the present thesis we utilized trait based approaches to assess effects of farm-based management practices on Collembola communities. In Chapter 2 we investigated how Collembola communities are affected by reduced tillage in comparison to conventional tillage practices. We evaluated Collembola communities in five long-term tillage field trials across European countries (Sweden, Germany, France, Romania and Spain). The study included differing bioclimatic regions to assess general effects of agricultural practices on soil Collembola across Europe. We found different ecological groups of Collembola defined by morphological traits to be differentially affected. Epedaphic Collembola were detrimentally affected while especially euedaphic Collembola were fostered by conventional tillage. Further, we found Collembola communities to be differentially affected depending on the dominating ecological groups at each field site. Reactions of Collembola communities resembled effects of tillage practices on organic carbon and total nitrogen revealing similar changes in depth distributions. Our results suggest nutrient supply in terms of organic carbon and total nitrogen in combination with favourable soil moisture conditions to be of critical importance for soil Collembola. The displacement of litter resources by tillage into deeper soil where they are available under preferable moisture conditions turned deeper soil layers into habitable space utilized especially by euedaphic species. In Chapter 3 we investigated the effect of Collembola and tillage on litter decomposition. We conducted a litterbag experiment in a long-term tillage field trial in Germany with reduced and conventional tillage. We buried litterbags filled with maize litter at the respective depth of tillage. Further, we investigated the incorporation of litter derived carbon into Collembola to quantify their dependence on litter resources under different tillage regimes. Collembola promoted decomposition by enhancing carbon loss and the transformation of litter into high quality resources as indicated by C/N ratios. Conventional tillage favoured colonization of litterbags by Collembola, especially that of euedaphic species. Furthermore, in conventional tillage fields Collembola depended more on litter material than in reduced tillage fields. In conclusion, Collembola accelerate litter transformation by increasing carbon loss and nitrogen accumulation. Facilitative effects on nitrogen capture from decomposing litter material by crops may contribute to the sustainability of arable systems. In Chapter 4 we investigated the effect of intercropping and genetic variation of crop species on Collembola communities. We sampled Collembola communities in two field trials in Germany containing monocultures of four genotypes of faba bean and intercropped stands of each genotype with winter wheat. The field sites differed in soil carbon and nitrogen content. Intercropping only promoted Collembola in the low carbon field site, but the effects were restricted to hemiedaphic Collembola while eu- and epedaphic Collembola remained unaffected. Further, at the low carbon site Collembola benefited from the bean genotype characterized by high tillering and short shoots which yielded the highest root biomass. The results suggest that root and shoot overyielding in intercropped stands led to increased availability of carbon resources for Collembola. Our results indicate that intercropping and the choice of plant genotypes promote Collembola communities if resources are scarce. Presumably the beneficial effects are mediated by the provision of litter and root resources and improved moisture conditions as well as habitat diversification. Overall, the results of Chapters 2 and 4 indicate the availability and quality of resources in combination with preferable moisture conditions to be of critical importance for Collembola. These abiotic factors determine habitat suitability and they surpass the importance of mechanical disturbance and soil compaction. Results of Chapter 3 highlighted the dependency of Collembola on litter resources in agricultural systems. In addition, it proved that Collembola accelerate litter decomposition thereby contributing to crucial ecosystem services. Altogether, the results of this thesis indicate that the response of Collembola to farm-based management practices depend on underlying changes in abiotic conditions. Generally, we showed the suitability of trait based approaches as tool to improve mechanistic understanding of the response of Collembola communities to farm-based management practices, which is urgently needed for the sustainable management of arable
dc.contributor.coRefereeKamp, Johannes Prof. Dr.
dc.subject.engfarm-based management practicesde
dc.affiliation.instituteBiologische Fakultät für Biologie und Psychologiede
dc.subject.gokfullBiologie (PPN619462639)de
dc.notes.confirmationsentConfirmation sent 2022-12-16T06:15:01de

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