List of tables .................................................. 1
List of figures ................................................. 2
Chapter 1: Introduction ......................................... 3
1.1 What are mycorrhizas? ...................................... 3
1.2 Arbuscular mycorrhiza - morphology and phylogeny ........... 3
1.3 Why are arbuscular mycorrhizas ecologically important? ..... 5
1.4 Ecological studies on arbuscular mycorrhizas ............... 6
1.5 The DIVA Jena program within the BIOLOG framework .......... 7
1.6 Objectives and structure of this thesis .................... 8
Chapter 2: Differences in the species composition of
arbuscular mycorrhizal fungi in spore, root and
soil communities in a grassland ecosystem ............ 9
2.1 Introduction ............................................... 9
2.2 Experimental procedures ................................... 10
2.2.1 Field site ......................................... 10
2.2.2 Root, spore and soil sampling from the field ....... 10
2.2.3 DNA extraction and nested PCR ...................... 11
2.2.4 Cloning and sequencing ............................. 12
2.2.5 Sequence analyses .................................. 12
2.2.6 Calculation of rarefaction and statistical
analysis ........................................... 13
2.3. Results ................................................... 14
2.4 Discussion ................................................. 19
Chapter 3: Interactive effects of mycorrhizae and
a hemiparasite on plant community productivity
and diversity ....................................... 22
3.1 Introduction .............................................. 22
3.2 Materials and Methods ..................................... 24
3.2.1 Study system ....................................... 24
3.2.2 Experiment 1: Multi-species experiment ............. 25
3.2.2.1 Experimental set-up and design ............ 25
3.2.2.2 Data collection ........................... 26
3.2.3 Experiment 2: Single-species experiment ............ 27
3.2.3.1 Experimental set-up and design ............ 27
3.2.3.2 Data collection ........................... 28
3.2.4 Statistical analysis ............................... 28
3.3 Results ................................................... 30
3.3.1 Mycorrhizal colonization ........................... 30
3.3.2 Effect of AMF on plant - hemiparasite
interactions ....................................... 30
3.3.3 Response of the grassland community to different
AMF treatments ..................................... 34
3.3.4 Response of the hemiparasite to different AMF
treatments ......................................... 36
3.3.5 Responses of single grown plant species to AMF
and importance of indirect effects ................. 37
3.4 Discussion ................................................ 39
3.4.1 Mycorrhizal fungi generate the negative effect
of the hemiparasite on plant community ............. 39
3.4.2 Mycorrhizal dependency of dominant species
determines community responses ..................... 39
3.4.3 Hemiparasitic plants profit from mycorrhizal
fungi .............................................. 40
3.4.4 Specific effects of AMF cannot be reduced to
functional complementarity ......................... 41
3.4.5 Importance of indirect effects varies among
fungal treatments .................................. 42
3.5 Conclusions ............................................... 42
Chapter 4: Bottom-up effects of arbuscular mycorrhizal fungi
across a plant-herbivore-parasitoid system .......... 44
4.1 Introduction .............................................. 44
4.2 Materials and methods ..................................... 45
4.2.1 Plant, aphid and parasitoid material ............... 45
4.2.2 Experimental set-up ................................ 46
4.2.3 Plant measurements ................................. 47
4.2.4 Aphid and parasitoid measurements .................. 48
4.2.5 Data analysis ...................................... 48
4.3 Results ................................................... 50
4.3.1 Plant responses .................................... 50
4.3.2 Aphid population development ....................... 53
4.3.3 Parasitoid responses ............................... 55
4.4 Discussion ................................................ 57
4.4.1 AMF and aphid effects on plants .................... 57
4.4.2 AMF Effects on aphids .............................. 58
4.4.3 AMF effects on parasitoids ......................... 59
4.5 Conclusions ............................................... 61
Chapter 5: General discussion .................................. 62
References ..................................................... 67
Summary ........................................................ 82
Zusammenfassung ................................................ 84
Appendix ....................................................... 86
Cooperations ................................................... 92
Acknowledgements ............................................... 93
Ehrenwörtliche Erklärung ....................................... 94
Curriculum vitae ............................................... 95
Publications ................................................... 96
|
