Altitude, Litter Quality and Availability of Root Derived Resources As Determinants of Decomposition Processes and Soil Microart
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ZENTRUM FÜR BIODIVERSITÄT UND NACHHALTIGE LANDNUTZUNG SEKTION BIODIVERSITÄT, ÖKOLOGIE UND NATURSCHUTZ − CENTRE OF BIODIVERSITY AND SUSTAINABLE LAND USE − SECTION: BIODIVERSITY, ECOLOGY AND NATURE CONSERVATION Altitude, litter quality and availability of root derived resources as determinants of decomposition processes and soil microarthropod community composition in tropical montane rainforests in Southern Ecuador Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultäten der Georg-August-Universität Göttingen vorgelegt von Diplom Biologin Franca Marian aus Offenbach Göttingen, Juni 2016 Referentin/Referent: Prof. Dr. Stefan Scheu Korreferentin/Korreferent: Prof. Dr. Mark Maraun Tag der mündlichen Prüfung: 19.08.2016 „Das ist überall dasselbe wo es zu wenig Licht gibt. Da spielt die Natur verrückt, weil sie sich unbeobachtet fühlt.“ aus „Rumo & Die Wunder im Dunkeln“ von Walter Moers Contents Summary ...................................................................................................................... 1 Chapter 1 ..................................................................................................................... 4 General Introduction ............................................................................................................ 4 Decomposition processes ......................................................................................................................... 5 Roots, rhizosphere and mycorrhizal fungi ................................................................................................ 6 Soil microarthropods, e.g. Oribatida ........................................................................................................ 7 Tropical montane rainforests and altitudinal gradients ........................................................................... 8 Study site ................................................................................................................................................ 10 Objectives and chapter outline ............................................................................................................... 11 References .............................................................................................................................................. 13 Chapter 2 ................................................................................................................... 18 Decomposition of leaf and root litter in tropical montane rainforests suggests strong nutrient limitation resulting in long-term carbon sequestration........................................................ 18 Abstract .................................................................................................................................................. 19 Introduction ............................................................................................................................................ 20 Material and methods ............................................................................................................................ 22 Results .................................................................................................................................................... 26 Discussion ............................................................................................................................................... 33 Acknowledgements ................................................................................................................................ 38 References .............................................................................................................................................. 38 Appendix ................................................................................................................................................. 43 Chapter 3 ................................................................................................................... 46 Changes in the structure of soil animal communities in decomposing leaf and root litter in tropical montane rainforests: Influence of altitude and litter origin ..................................... 46 Abstract .................................................................................................................................................. 47 Introduction ............................................................................................................................................ 48 Material and methods ............................................................................................................................ 50 Results .................................................................................................................................................... 53 Discussion ............................................................................................................................................... 61 Acknowledgements ................................................................................................................................ 67 References .............................................................................................................................................. 67 Appendix ................................................................................................................................................. 73 Chapter 4 ................................................................................................................... 82 Roots, mycorrhizal fungi and altitude as determinants of litter decomposition and soil animal communities in tropical montane rainforests ...................................................................... 82 Abstract .................................................................................................................................................. 83 Introduction ............................................................................................................................................ 84 Material and methods ............................................................................................................................ 86 Results .................................................................................................................................................... 91 Discussion ............................................................................................................................................... 99 Acknowledgements .............................................................................................................................. 105 References ............................................................................................................................................ 105 Appendix ............................................................................................................................................... 112 Chapter 5 .................................................................................................................. 114 General Discussion ............................................................................................................ 114 Regulatory forces of litter decomposition ............................................................................................ 115 Soil microarthropod abundance and diversity ..................................................................................... 118 Conclusions ........................................................................................................................................... 121 References ............................................................................................................................................ 122 Acknowledgements ................................................................................................... 125 List of Publications..................................................................................................... 127 Thesis Declarations .................................................................................................... 128 Plagiarism declaration ............................................................................................... 129 Summary Summary Decomposition processes in the high tropical Andes are complex and influenced by a variety of biotic and abiotic factors. Tropical montane rainforests of the high Andes harbour large stocks of dead organic material and little is known on the regulatory forces responsible for this accumulation of carbon. Litter quality, climate and the decomposer community are known from other systems as the main factors controlling decomposition rates. Microarthropods play a major role in regulating decomposition processes due to the impact they have on their surrounding habitat. They are known to regulate organic matter turnover and influence nutrient cycling via direct and indirect processing of organic matter entering the soil system as both litter fall and root exudates. However, there is a lack of knowledge on interrelationships between litter decomposition and the structure of soil microarthropod communities in tropical montane rainforests. This thesis focuses on disentangling the relative importance of regulatory forces, e.g. litter quality and local biotic and abiotic conditions, in regulating long term decomposition processes