GeloriniPhD (PDF , 6973kb) - University of York

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CHAPTER 1 Diversity and ecology of tropical African fungal spores ‘short rains’ from late October through December. The local climate is tropical semi-arid, with monthly mean daytime temperatures ranging from 26 °C in July-August to 30 °C in February-March. Total annual rainfall is ca. 565 mm yr -1 and surface evaporation ca. 1735 mm yr -1 , resulting in a negative water balance for Lake Challa (Payne, 1990). The lake is maintained by shallow groundwater originating from rainfall falling higher up the slope of Mt. Kilimanjaro. Rainfall in East Africa is spatially modified by the dissected topography of the plateau, and inter-annually by cyclic fluctuations in sea surface temperature linked to the Indian Ocean Dipole and the El Niño Southern Oscillation (Marchant et al., 2006). Today Lake Challa is surrounded by a landscape of mostly open bush and grass savanna with scattered woodland trees and shrubs, and strips of moist riverine forest in (seasonally dry) stream gullies (White, 1983); the northern and western outer slopes of the Challa caldera are covered with dry colline savanna forest of Acalypha fruticosa and Acacia species (Hemp, 2006; Fig. 1.1c). The inner caldera slopes are covered by a narrow strip of evergreen riverine forest on rock-fall along the shoreline, a dry ‘succulent’ forest with Commiphora baluensis, Haplocoelum foliolosum and Euphorbia bussei on steep middle slopes, and open grassland with scattered trees and shrubs on gentle higher slopes below the rim. In 2005 three parallel piston cores of 20-22 m length were recovered from a mid-lake location (3° 19.05’ S, 37° 41.88’ E). Following cross-correlation of overlapping core sections these together form a 21.65-m long composite sequence of mostly finely laminated organic muds. Excision of five turbidite horizons yielded a single 20.82-m long sequence of continuous deepwater sedimentation (Verschuren et al., 2009). Lake Challa’s spatially uniform sedimentation and relatively stable physical limnology over the past 25,000 years (Moernaut et al., 2010) accumulated a climate archive with high temporal resolution and virtually unprecedented radiometric ( 210 Pb, 14 C) age control (see the supplementary online information of Verschuren et al., 2009). Age indications in the present paper are given in calendar years BP (Before Present), with Present being 1950 AD. 1.2.2. Laboratory procedures Sediment samples of 1 ml volume extracted for microfossil analysis were boiled in 10 % Na-pyrophosphate, dehydrated with 96% acetic acid and treated with an acetolysis mixture of one part H 2 SO 4 to nine parts acetic anhydride. The samples were heated in this mixture to 100 °C for ca. 10 min in a water bath. Sample tubes were then cooled, centrifuged and washed with distilled water, and centrifuged again in 96 % ethanol. The separation of organic material from sand and clay was accomplished in a heavy liquid (bromoform-ethanol mixture, specific gravity 2). The samples were finally washed in 96 % alcohol, centrifuged, put in glycerine and stored overnight in an oven at 40 °C before being mounted on microscope slides for identification and counting. Following the methodology initiated by van Geel (1972, 1978), ‘Type’ numbers were assigned to each type of non-pollen microfossil with characteristic morphology. Their coded designation of origin HdV stands for Hugo de Vries-Laboratory, University of Amsterdam. Using mycological literature, in many cases these Types, or fossil morphotaxa, could be positively identified as extant fungal taxa at the genus or species level. The word ‘Type’ sensu van Geel (1978) has no further taxonomic significance. In most cases it represents a more or less homogeneous morphological entity and can be considered as a provisionally named form-species. However, since morphologically similar European and African types can differ substantially in size and, given the enormous diversity of tropical fungi, may be subject to taxonomic variation at the genus or species level, we used new type numbers for related African types. We analysed fossil NPP assemblages in a total of 93 sediment samples spaced evenly at 32 cm (~400 years) intervals along the 25,000-year sediment sequence, and spaced at 8 cm (~100 years) intervals over the last 2000 years (Fig. 1.2). The abundances of individual NPP taxa are expressed as percentages relative to a non-local pollen sum. The non-local pollen sum excludes aquatic plants, here mostly Cyperaceae and Typha. NPPs in each sample were counted until ca. 200 pollen grains (mean 206; range 100-245) had been encountered. Given this combination of time resolution and absolute counts, we interpret trends in the NPP curves at the millennial time scale. Stratigraphic zonation with CONISS (Grimm, 1987) was based on the distributions of 37 fungal spore taxa found in at least 10 sediment samples. . 44 .
. 45 . CHAPTER 1 Diversity and ecology of tropical African fungal spores Fig. 1.2. Stratigraphic distribution and zonation of fossil fungi and some other NPPs in sediments of Lake Challa covering the last 25,000 years; taxon abundances expressed as percentages of the sum of non-local pollen.
Page 3: 2011 Thesis submitted in partial fu
Page 7: Voorwoord . 7 . VOORWOORD Aarde, wa
Page 10: DANKWOORD / ACKNOWLEDGEMENTS door K
Page 14 and 15: TABLE OF CONTENTS A.1. Septated spo
Page 17 and 18: Abstract . 17 . ABSTRACT In tropica
Page 19 and 20: Introduction . 19 . INTRODUCTION
Page 21 and 22: . 21 . INTRODUCTION Atlantic Ocean
Page 23 and 24: 1 Figure 2 Global Land-Cover 2000 m
Page 25 and 26: Fig. iv. Rainfall variation in east
Page 27 and 28: . 27 . INTRODUCTION metallurgy main
Page 29 and 30: . 29 . INTRODUCTION analysis of fos
Page 31 and 32: . 31 . INTRODUCTION (iv) illuminate
Page 33 and 34: . 33 . INTRODUCTION Coniochaeta spe
Page 35 and 36: . 35 . INTRODUCTION university pres
Page 37 and 38: . 37 . INTRODUCTION Mumbi, C.T., Ma
Page 39 and 40: . 39 . INTRODUCTION lipids in an eq
Page 41 and 42: . 41 . CHAPTER 1 Diversity and ecol
Page 43: Equator b 0° Altitude (m) a >3000
Page 47 and 48: 1.3.1. Descriptions and illustratio
Page 49 and 50: Type HdV-1005: Brachydesmiella sp.
Page 51 and 52: Type HdV-1020 (Plate II) . 51 . CHA
Page 55 and 56: Type HdV-1051 (Plate III) . 55 . CH
Page 63 and 64: RefeRences . 63 . CHAPTER 1 Diversi
Page 69: . 69 . CHAPTER 1 Diversity and ecol
Page 72 and 73: CHAPTER 2 Modern non-pollen palynom
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CHAPTER 2 Modern non-pollen palynom
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CHAPTER 3 Effects of Land use on th
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CHAPTER 4 Validation of non-pollen
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General discussion and conclusion .
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. 189 . GENERAL DISCUSSION AND CONC
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SAMENVATTING beperkingen (i.v.m. de
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APPENDICES Appendix I. Raw NPP data
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APPENDICES Mahuhura Kitere Katanda
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APPENDICES Appendix II. Raw NPP dat
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APPENDICES L. Chibwera Identificati
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APPENDICES L. Chibwera Identificati
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APPENDICES Appendix III. Raw NPP da
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APPENDICES L. Kanymukali Identifica
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APPENDICES L. Kanymukali Identifica
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Photograph by Bob Rumes Front cover
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