ZENTRUM FÜR BIODIVERSITÄT UND NACHHALTIGE LANDNUTZUNG SEKTION BIODIVERSITÄT, ÖKOLOGIE UND NATURSCHUTZ CENTRE OF BIODIVERSITY AND SUSTAINABLE LAND USE SECTION: BIODIVERSITY, ECOLOGY AND NATURE CONSERVATION The soil food web of temperate deciduous forests: litter and root resources as driving factors, and soil fauna effects on ecosystem processes Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultäten der Georg-August-Universität Göttingen vorgelegt von Diplom-Biologin Diana Grubert aus Strausberg Göttingen, Februar 2016 Referentin/Referent: Prof. Dr. Stefan Scheu Korreferentin/Korreferent: Prof. Dr. Mark Maraun Tag der mündlichen Prüfung: 04.04.2016 Table of contents Summary .......................................................................................................................... 7 Chapter 1 General Introduction ........................................................................................................ 9 Aboveground - belowground interactions and ecosystem functioning .......................... 10 Stable isotopes ................................................................................................................. 11 Soil biota ........................................................................................................................... 12 Microorganisms ............................................................................................................ 12 Microarthropods .......................................................................................................... 12 Earthworms .................................................................................................................. 13 Soil fauna interactions .................................................................................................. 13 Study site .......................................................................................................................... 14 Study objectives and chapter outline............................................................................... 15 Main hypotheses .......................................................................................................... 15 Chapter 2 ...................................................................................................................... 16 Chapter 3 ...................................................................................................................... 16 Chapter 4 ...................................................................................................................... 16 References ........................................................................................................................ 17 Chapter 2 The importance of aboveground and belowground resources for the microbial community of temperate deciduous forests ...................................................................................... 24 Abstract ............................................................................................................................ 25 Introduction ...................................................................................................................... 26 Material and methods ...................................................................................................... 27 Study site ...................................................................................................................... 27 Experimental set up ..................................................................................................... 28 Sampling and analytical procedure .............................................................................. 29 Calculations and statistical analyses ............................................................................ 30 Results .............................................................................................................................. 31 Response of soil microorganisms to roots and litter ................................................... 31 Response of soil microorganisms to mycorrhizal type and identity of roots .............. 31 Response of soil microorganisms to quality and identity of leaf litter ........................ 32 Discussion ......................................................................................................................... 33 Acknowledgements .......................................................................................................... 37 References ........................................................................................................................ 37 Chapter 3 The importance of aboveground and belowground resources for soil invertebrates of temperate deciduous forests .......................................................................................... 43 Abstract ............................................................................................................................ 44 Introduction ...................................................................................................................... 45 Material and methods ...................................................................................................... 47 Study site ...................................................................................................................... 47 Experimental set up ..................................................................................................... 47 Sampling and analytical procedure .............................................................................. 48 Calculations and statistical analyses ............................................................................ 48 Results .............................................................................................................................. 49 Response of microarthropods to soil pH and soil moisture......................................... 50 Response of microarthropods to presence of litter and roots .................................... 51 Response of microarthropods to mycorrhizal type and identity of roots ................... 55 Response of microarthropods to quality and identity of leaf litter ............................. 56 Discussion ......................................................................................................................... 58 Conclusions ....................................................................................................................... 61 Acknowledgements .......................................................................................................... 61 References ........................................................................................................................ 61 Chapter 4 Species identity and diversity rather than trait similarity affects macrofauna - mesofauna interactions and their importance for ecosystem processes ............................................. 69 Abstract ............................................................................................................................ 70 Introduction ...................................................................................................................... 71 Material and methods ...................................................................................................... 72 Soil and plant material ................................................................................................. 72 Earthworms and collembolans ..................................................................................... 73 Experimental set up ..................................................................................................... 74 Sampling and analytical procedure .............................................................................. 74 Calculations and statistical analyses ............................................................................ 75 Results .............................................................................................................................. 76 Effects of soil animals and their interactions on leaf litter mass loss .......................... 76 Effects of soil animals and their interactions on 15N cycling ........................................ 76 Soil animal biomass and abundance ............................................................................ 79 15N incorporation into soil animals .............................................................................. 80 Discussion ......................................................................................................................... 82 Conclusion ........................................................................................................................ 84 Acknowledgements .......................................................................................................... 85 References ........................................................................................................................ 86 Chapter 5 General Discussion .......................................................................................................... 89 The role of aboveground and belowground resources for forest soil organisms ........... 90 The importance of litter associated soil animals for ecosystem processes ..................... 92 Species identity, community composition and soil fauna interactions ..........................