Environmental Botany: Study Unit 1 - Flora of South Africa Study Africa

Study Unit 1: Flora of South Africa (Environmental Botany)

• Course and Faculty Overview

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  • University: NWU (North-West University).

  • Subject: STUDY UNIT 1: FLORA OF SOUTH AFRICA / LEEREENHEID 1: FLORA VAN SUID-AFRIKA.

  • Department/Sector: Environmental Botany, Botanical Exploration, Plant Taxonomy, and Ecology.

  • Dr. Madeleen Struwig (MC): Senior Lecturer specializing in Phylogeny, TaxonoLecturers (Dosente):

    • my, Plant Taxonomy, and the Flora of South Africa.

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  • Key Themes: Introduction to Topsoil and Subsoil dynamics, New Discovery processes, and the general explProf. Stefan Siebert (PC): Specialized in Plant Ecology and Ecology 101.oration of South African flora.

Learning Objectives / Leerdoelwitte

• Identification and Description: Identify and describe the major floristic regions and biomes within South Africa.

• Recognition of Types: Recognize the key floristic types associated with each specific region.

• Environmental Understanding: Understand the geographic distribution and the environmental conditions (climate, geology, soil) of each biome, with specific focus on Fynbos, Succulent Karoo, and Savanna.

ext of South Africa

• Location: South Africa is situated in the Southe

Geographical Contrn Hemisphere on the African continent.

• Neighboring Countries (Buurlande):

  • Namibia.

  • Botswana.

  • Zimbabwe.

  • Mozambique.

  • Swaziland (eSwatini).

  • Lesotho (enclave).

• Other Southern African/Indian Ocean Countries mentioned:

  • Angola.

  • Zambia.

  • Malawi.

  • Madagascar.

  • Comoros.

Statistical Importance of South African Flora

• Species Diversity in the Flora of Southern Africa (FSA):

  • The FSA contains approximately $24,000$ species.

  • Endemism Rate: Approximately $60\,\%$ of these species are endemic to the region.

  • Global Comparison: The FSA houses $10\,\%$ of the world’s flora on only $2.5\,\%$ of the world's land surface.

• Biodiversity Rankings:

  • South Africa is one of only $17$ mega-diverse countries globally.

  • It is specifically mega-diverse regarding plant life.

  • Global Rank: Third most biodiverse country in the world, following Brazil ($1$) and Indonesia ($2$).

• Speciation Dynamics:

  • High levels of endemism are described as comparable to islands.

  • The region features high speciation events with $560$ genera.

  • The species-to-genus ratio is recorded as $\text{species:genus} = 3:2$.

Top 20 Plant Families in FSA by Endemism (Greater than 85\%)

• Aizoaceae: Rank 1 in FSA, Rank 98 in the world; $98\,\%$ endemism.

• Geraniaceae: Rank 17 in FSA; $96\,\%$ endemism.

• Asteraceae: Rank 2 in FSA, Rank 1 in the world; $86\,\%$ endemism.

• Campanulaceae: Rank 18 in FSA; $96\,\%$ endemism.

• Liliaceae: Rank 4 in FSA, Rank 11 in the world; $89\,\%$ endemism.

• Crassulaceae: Rank 20 in FSA; $89\,\%$ endemism.

• Iridaceae: Rank 5 in FSA; $97\,\%$ endemism.

• Selaginaceae: Rank 21 in FSA; $97\,\%$ endemism.

• Ericaceae: Rank 6 in FSA, Rank 21 in the world; $99\,\%$ endemism.

• Polygalaceae: Rank 23 in FSA; $88\,\%$ endemism.

• Asclepiadaceae: Rank 8 in FSA, Rank 13 in the world; $87\,\%$ endemism.

• Oxalidaceae: Rank 25 in FSA; $98\,\%$ endemism.

• Scrophulariaceae: Rank 9 in FSA, Rank 8 in the world; $87\,\%$ endemism.

• Thymelaeaceae: Rank 26 in FSA; $95\,\%$ endemism.

• Proteaceae: Rank 13 in FSA; $97\,\%$ endemism.

• Apiaceae: Rank 28 in FSA, Rank 17 in the world; $90\,\%$ endemism.

• Rutaceae: Rank 15 in FSA; $94\,\%$ endemism.

• Santalaceae: Rank 29 in FSA; $94\,\%$ endemism.

• Restionaceae: Rank 16 in FSA; $94\,\%$ endemism.

• Sterculiaceae: Rank 30 in FSA; $85\,\%$ endemism.

Floristic Regions and Centres of Endemism

• Principal Regions:

  1. Cape Floristic Region (CFR): Includes the Kamiesberg Centre (1.1).

  2. Succulent Karoo Region (SKR): Divided into several centres:

     • 2.1 Gariep Centre (GC).

     • 2.2 Knersvlakte Centre (KVC).

     • 2.3 Little Karoo Centre (LKC).

     • 2.4 Worcester-Robertson Karoo Centre (WRKC).

     • 2.5 Hantam-Roggeveld Centre (HRC).

  3. Maputaland-Pondoland Region (MPR): Divided into:

     • 3.1 Maputaland Centre (MC).

     • 3.2 Pondoland Centre (PC).

• Additional Centres of Endemism:

  • 4. Albany Centre (AC).

  • 5. Drakensberg Alpine Centre (DAC).

  • 6. Barberton Centre (BC).

  • 7. Wolkberg Centre (WC).

  • 8. Sekhukhuneland Centre (SKC).

  • 9. Soutpansberg Centre (SC).

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  10. Chimanimani-Nyanga Centre (CIC).

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  11. Great Dyke Centre (GDC).

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  12. Kaokoveld Centre (KOC).

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  13. Griqualand West Centre (GWC).

African Phytochoria (Regional Centres of Endemism)

• Phytochorial Units (Fitokoria):

  1. Guineo-Congolian.

  2. Zambezian.

  3. Sudanian.

  4. Somalia-Masai.

  5. Cape.

  6. Karoo-Namib.

  7. Mediterranean.

  8. Afromontane & Afroalpine (Archipelago-like center).

  9. Swahilian.

• Transition Zones and Mosaics:

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  10. Guinea-Congolia/Zambezian.

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  11. Guinea-Congolia/Sudanian.

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  12. Lake Victoria (Regional Mosaic).

  • 13a. Swahilian/Maputaland.

  • 13b. Kalahari-Highveld.

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  14. Sahel.

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  15. Maputaland-Pondoland (Regional Mosaic).

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  16. Sahara.

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  17. Mediterranean/Sahara.

Global Floristic Kingdoms

1. Holarctic: Including Circumboreal, North American Atlantic, Rocky Mountain, Madrean, Macaronesian, Mediterranean, Irano-Turanian, Saharo-Arabian, and Eastern Asiatic.

2. Palaeotropical: Including Guineo-Congolian, Sudano-Zambezian, Madagascan, Indian, Indochinese, Malesian, Polynesian, Hawaiian, and Neocaledonian.

3. Neotropical: Including Caribbean, Amazonian, Brazilian, and Andean.

4. South African (Cape Kingdom): Distinct global kingdom localized to the southern tip of Africa.

5. Australian: Including Northeast Australian and Central Australian.

6. Holantarctic: Including Patagonian and Neozeylandic.

Biodiversity Hotspots (Brandpunte)

• Definition: Regions characterized by the highest species diversity and endemism, while also facing the worst danger of human-induced extinction.

• The "Hottest" Hotspot: The equatorial mountain forests of the Western Amazon (home to $50,000$ species, representing one-fifth of all plants on Earth).

• Global Hotspot Examples: Mesoamerica, Tropical Andes, Caribbean, Brazil's Atlantic Forest/Cerrado, Mediterranean Basin, Caucasus, Indo-Burma, Western Ghats/Sri Lanka, New Zealand, and Madagascar.

• South African Hotspots:

  • Cape Floristic Province: Houses approximately $9,000$ plant species with extremely high endemism (~$70\,\%$).

  • Succulent Karoo: Listed as a significant global biodiversity hotspot.

Drivers of High Floristic Diversity in South Africa

• Ecological Diversity Drivers:

  • Climate Transition: South Africa is a transitional zone between subtropical summer rainfall and moderate winter rainfall regions.

  • Rainfall Seasonality: Includes zones with rainfall all year, winter, early summer (December), mid-summer (January), late summer (February), and very late summer (March-May).

  • Complex Topography: Includes diverse landscapes like mountains, coastal plains, and the continental shelf.

  • Heterogeneous Geology: A diverse geological map (sedimentary, volcanic, and intrusive rocks) yields diverse soil types.

• Floristic Diversity Totals:

  • $6$ Phytochoria.

  • $9$ Biomes.

  • Over $50$ bioregions (main vegetation types).

The Nine Biomes of South Africa

1. Fynbos

2. Succulent Karoo

3. Desert

4. Nama-Karoo

5. Grassland

6. Savanna

7. Albany Thicket

8. Indian Ocean Coastal Belt

9. Forests