The Vegetation of Omusati and Oshana Regions, Central- Northern Namibia © University of Pretoria
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The vegetation of Omusati and Oshana Regions, central- northern Namibia by FRANSISKA NDIITEELA KANGOMBE Submitted in partial fulfillment of the requirements for the degree MAGISTER SCIENTIAE in the Department of Plant ScienceFaculty of Natural and Agricultural Sciences University of Pretoria December 2010 Supervisor: Prof. Dr. G.J. Bredenkamp Co-supervisor: Mr. B.J. Strohbach © University of Pretoria ABSTRACT The vegetation of Omusati and Oshana Regions, central-northern Namibia by FRANSISKA NDIITEELA KANGOMBE Supervisor: Prof. Dr. G.J. Bredenkamp Submitted in partial fulfillment of the requirements for the degree MAGISTER SCIENTIAE in the Department of Plant Science, Faculty of Natural and Agricultural Sciences University of Pretoria December 2010 Central-northern Namibia is home to an approximate 43% of the country’s population, a large proportion of which still depends directly on natural resources for their livelihoods. The main land use in this area is agro-silvo-pastoralism i.e. a combination of subsistence farming and silvi-culture. The few phytosociological and biodiversity data available in Namibia are not substantial to motivate environmental management and sustainable utilization of the country’s natural wealth. The Vegetation Survey Project of Namibia coupled with the BIOTA southern Africa Project therefore share a common goal of re-classifying Namibian vegetation by building on the Preliminary Vegetation Map of Namibia of 1971 and the Homogenous Framing Areas Report of 1979. The vegetation of Omusati and Oshana regions which are situated in the Mopanne Savanna in central-northern Namibia was classified and described by subjecting 415 relevés to multivariate analysis i.e. classification and ordination. The geographical distribution of these community types was established by supervised classification of satellite data of the study area. Data collected in this study will be used for hypothesis generation of further ecological investigations while the map can be used for planning and conservation of vegetation resources in the area. TABLE OF CONTENTS LIST OF FIGURES .....................................................................................................iv LIST OF TABLES ........................................................................................................v ABREVIATIONS AND ACRONYMS........................................................................vi SOFTWARES ..............................................................................................................vi CHAPTER 1. INTRODUCTION.................................................................................1 1.1 Thematic Background ............................................................................................1 1.2 The study of plant communities..............................................................................2 1.3 The BIOTA southern Africa Project.......................................................................5 1.4 Literature Review...................................................................................................9 1.5 Background on Namibia....................................................................................... 12 1.5.1 The vegetation ..................................................................................................................................... 13 1.5.2 Natural resources and land use ............................................................................................................ 15 1.6 Background on central-northern Namibia............................................................. 16 1.6.1 Location and physical environment..................................................................................................... 16 1.6.2 Geology ............................................................................................................................................... 16 1.6.3 Soils ..................................................................................................................................................... 18 1.6.4 Climate................................................................................................................................................. 20 1.6.5 The people ........................................................................................................................................... 20 1.6.6 Land use............................................................................................................................................... 21 1.7 Using remote sensing in vegetation mapping........................................................ 23 1.7.1 Types of image classification .............................................................................................................. 26 CHAPTER 2. PROBLEM STATEMENT ................................................................. 27 2.1 Land use types and intensities .............................................................................. 28 2.2 Climate variability................................................................................................ 29 CHAPTER 3. AIMS OF THE STUDY ...................................................................... 30 3.1 Research Objectives............................................................................................. 30 3.2 Research Questions.............................................................................................. 31 3.3 Study Approach ................................................................................................... 31 CHAPTER 4. METHODS .......................................................................................... 32 4.1 Study Site: Omusati and Oshana Regions............................................................. 32 4.2 Data collection ..................................................................................................... 33 4.3 Data analysis........................................................................................................ 35 4.3.1 Multivariate statistics (classification and ordination) .......................................................................... 35 ii 4.3.2 Basic Statistics..................................................................................................................................... 37 4.4 Vegetation Mapping............................................................................................. 38 4.4.1 Accuracy Assessment........................................................................................ 39 CHAPTER 5. RESULTS ............................................................................................ 42 5.1 Results Overview................................................................................................. 42 5.2 Vegetation description.......................................................................................... 52 5.2.1 Leptochloa fusca - Nymphaea nouchali wetlands vegetation alliance................................................. 52 5.2.1.1 Nymphaea nouchali - Oryzidium barnabadii pond association (Association 1)................... 53 5.2.1.2 Eragrostis rotifer - Eragrostis cilianensis oshanas association (Association 2)................... 54 5.2.2 Hyphaene petersiana - Acacia arenaria shrublands vegetation alliance............................................. 57 5.2.2.1 Hyphaene petersiana - Acacia hebeclada shrublands association (Association 3) .............. 57 5.2.2.2 Odyssea paucinervis - Hirpicium gorterioides saline grasslands association (Association 4)59 5.2.3 Eragrostis trichophora - Colophospermum mopane shrublands vegetation alliance .......................... 61 5.2.3.1 Eragrostis viscosa - Colophospermum mopane wet shrublands association (Association 5)62 5.2.3.2 Acacia nilotica - Colophospermum mopane dry shrublands association (Association 6) .... 65 5.2.3.3 Pennisetum glaucum crop fields association (Association 7) ............................................... 68 5.2.4 Terminalia prunioides - Colophospermum mopane shrublands vegetation alliance ........................... 70 5.2.4.1 Aristida adscensionis - Colophospermum mopane shrublands association (Association 8). 71 5.2.4.2 Terminalia sericea - Colophospermum mopane shrublands association (Association 9)..... 73 5.2.5 Combretum collinum - Terminalia sericea shrublands vegetation alliance ......................................... 75 5.2.5.1 Combretum collinum - Terminalia sericea shrublands association (Association 10)........... 76 5.3 Vegetation mapping ............................................................................................. 80 5.4 Vegetation monitoring.......................................................................................... 82 CHAPTER 6. DISCUSSION ..................................................................................... 86 6.1 Phytosocilogical methods..................................................................................... 86 6.2 The ordinations .................................................................................................... 86 6.3 Vegetation description: patterns and relationships ................................................ 89 6.3.1Comparison to other vegetation surveys............................................................................................... 94 6.4 Vegetation mapping ............................................................................................