Floristic Variation of the Igapó Forests along the Negro River, Central Amazonia Thesis submitted in partial fulfillment of the requirements of the degree of Dr. rer. nat of the Faculty of Forest and Environmental Sciences Albert-Ludwigs Universität, Freiburg,Germany by Juan Carlos Montero Terrazas Freiburg im Breisgau 2012 Dean: Prof. Dr. Jürgen Bauhus First supervisor: Prof. Dr. Dr. h.c. Albert Reif Second supervisor: Dr. habil. Florian Wittmann Second reviewer: Prof. Dr. Dieter. R. Pelz Date of Disputation: 13 November 2012 List of Contents List of Contents List of Contents ............................................................................................................1 List of Figures and Tables............................................................................................3 Statement of Originality................................................................................................5 Statement of Contributions to this PhD Thesis ............................................................6 Acknowledgements......................................................................................................8 Zusammenfassung.....................................................................................................10 Abstract......................................................................................................................13 1 General introduction........................................................................................17 1.1 Amazonian floodplain forests .....................................................................17 1.2 The course of the Negro River: main environmental gradients ..................19 1.3...... Patterns of floristic variation in Amazonian forests with emphasis on floodplain evidence ....................................................................................21 1.4 Scope and outline of the thesis ..................................................................22 2 Floristic variation across 600 km of inundation forests (Igapó) along the Negro River......................................................................................................26 2.1 Introduction.................................................................................................26 2.2 Methods......................................................................................................28 2.2.1 Study area..........................................................................................28 2.2.2 Floristic inventories.............................................................................30 2.2.3 Data analysis......................................................................................30 2.3 Results .......................................................................................................33 2.3.1 Floristic gradients ...............................................................................33 2.3.2 Floristic composition and importance values......................................36 2.3.3 Tree species richness and diversity ...................................................38 2.3.4 Floristic resemblance between river sections.....................................41 2.3.5 Diversity gradients of igapó across geographical regions and geological zones ................................................................................................41 2.3.6 Comparison of igapó with várzea .......................................................42 2.4 Discussion ..................................................................................................43 2.4.1 Spatial floristic patterns ......................................................................43 2.4.2 Floristic composition ...........................................................................45 2.4.3 Species richness and diversity patterns .............................................46 2.4.4 Diversity gradients at continental scale ..............................................48 2.4.5 On the relationship between diversity of igapó and várzea ................49 2.5 Conclusion..................................................................................................50 3 Effect of flooding regime and soils on tree species composition and diversity of igapó forests across the Negro River, central Amazonia .......53 3.1 Introduction.................................................................................................53 3.2 Methods......................................................................................................56 3.2.1 Study area..........................................................................................56 3.2.2 Data collection....................................................................................60 3.2.3 Data Analysis......................................................................................62 3.3 Results .......................................................................................................64 3.3.1 Variation of flooding regime and soils along the course of the river ...64 3.3.2 Floristic variation between and within river sections...........................65 3.3.3 Environment in relation to tree community parameters ......................67 3.3.4 Rarity and commonness in response to the flooding gradient............68 3.3.5 Diversity patterns along flooding gradients.........................................69 3.3.6 Relation between spatial scale and floristic similarity.........................73 3.3.7 Tree composition according to flood tolerance...................................73 3.4 Discussion ..................................................................................................75 3.4.1 Environmental heterogeneity along the course of the Negro River ....75 1 List of Contents 3.4.2 Diversity patterns along flooding gradients.........................................76 3.4.3 Rarity and commonness.....................................................................78 3.4.4 Tree composition along flooding gradients.........................................79 3.4.5 On the effects of geographic distance and environmental (dis)similarity ……………………………………………………………………………...81 3.5 Conclusion..................................................................................................82 4 The igapó of the Negro River in central Amazonia: Linking late- successional inundation forest with fluvial geomorphology .....................85 4.1 Introduction.................................................................................................85 4.1.1 Physical setting of the study area.......................................................87 4.1.2 Study area and scope.........................................................................89 4.2 Methods......................................................................................................89 4.2.1 Floristic inventories.............................................................................89 4.2.2 Hydrology and Geomorphology..........................................................90 4.2.3 Soil sampling ......................................................................................90 4.2.4 Analysis of floristic data ......................................................................90 4.3 Results .......................................................................................................92 4.3.1 Fluvial geomorphology.......................................................................92 4.3.2 Hydrology ...........................................................................................94 4.3.3 Floristic differentiation and species composition ................................95 4.3.4 Species richness and diversity patterns .............................................97 4.3.5 Forest vertical structure ......................................................................98 4.4 Discussion ................................................................................................100 4.4.1 Relationship between geomorphology, hydrology and igapó forests 100 4.4.2 The Holocene: floodplain evolution and the spatial distribution of the igapó forest ......................................................................................................106 4.5 Conclusion................................................................................................107 5 Synthesis and Perspectives..........................................................................110 5.1 Key Findings.............................................................................................110 5.2 Implications for classification and conservation of Amazonian wetlands .114 References...............................................................................................................116 Appendix I ................................................................................................................128 Appendix II ...............................................................................................................130 2 List of Figures and Tables List of Figures and Tables Figures Figure 1.1: The meeting of the white and black waters of the Solimões and Negro rivers. Physiognomy of a typical igapó forest.....................................................19 Figure 1.2: Location of the Negro River in the Amazonian hydrological network and its confluence with the Solimões River at Manaus in central Amazonia. ...........20