Part 3

• South Africa is host to a range of biomes, which encapsulate the huge biological diversity of the country
• Reasons for diversity of biomes in South Africa


  • Strong environmental gradients in rainfall, temperature, geology, soils
  • Strong effect of fire
  • Strong effect of herbivory on vegetation
• South Africa is one of only two arid biodiversity hotspots in the world
• The Succulent Karoo contains the richest variety of succulents on Earth
• The Succulent Karoo has more than 5000 plant species, 2000 of which are endemic to South Africa
• The Succulent Karoo has a high number of rare and red data plant species
• Succulent Karoo Biome


  • Winter rainfall desert (100 - 300 mm/yr)
  • Rainfall highly variable
  • Extreme summer aridity

  
• Vegetation of Succulent Karoo

  • Dwarf shrubland dominated by leaf succulents
  • Succulents are drought-adapted with thick, fleshy leaves or stems for water storage
• Distinctive stem succulents in Succulent Karoo


  • Halfmens (Pachypodium namaquanum)
• The Succulent Karoo has experienced a recent and explosive diversification of Vygies (family Mesembryanthemaceae)
• Succulent plants in Succulent Karoo


  • Lithops (family Aizoaceae)
• Advantage of Lithops looking like pebbles


  • Camouflage
• The Succulent Karoo is the richest succulent flora on Earth
• The Succulent Karoo is one of only two entirely arid ecosystems to earn hotspot status
• 29% of the 6356 plant species in the Succulent Karoo are endemic
• 38% of the 6356 plant species in the Succulent Karoo are threatened
• Only 2.5% of the Succulent Karoo is formally protected
• Over 90% of the Succulent Karoo is used for natural grazing, which is theoretically compatible with conservation
• The Succulent Karoo Programme aims to secure land in priority areas, expand partnerships, link livelihoods and biodiversity, capitalise on climate change and renewable energy, involve the mining sector, and raise awareness
• Nama Karoo Biome


  • Hot summers, cool winters with frost, extreme temperature range
  • Distribution determined primarily by rainfall (100 - 500 mm/yr)
  • Low shrubs, grasses with some small trees
  • Comparably low biodiversity
  • 3rd largest biome in South Africa

  
• The Nama Karoo is separated from the Succulent Karoo by elevation, temperature and rainfall
• Vegetation of Nama Karoo

  • Dwarf open shrubland with some grasses
  • Mostly deciduous
  • Shrubs increase and grasses decrease with increasing aridity
• The Nama Karoo has insufficient fuel load to sustain fires
• Historically, large herds of springbok migrated across the Nama Karoo, but hunting, fences and windmills have now halted game migrations
• Why are goats/sheep more destructive grazers than cows?


  Goats and sheep are more destructive because they are more selective grazers and can overgraze an area, whereas cows are less selective and graze more evenly
• Why are there few cows in the Karoo?

  The Karoo has insufficient rainfall and vegetation to support large herds of cattle
• The Nama Karoo has relatively species-poor fauna and very few rare or Red Data plant species
• Sound agricultural practices like eliminating burning for livestock grazing can help conserve the Nama Karoo
• Albany Subtropical Thicket Biome


  • Dense, woody thicket vegetation, semi-succulent and thorny
  • Many subtropical elements
  • Highly fragmented and found mostly in river valleys
  • Has high carbon dioxide storage ability
• Characteristics of Albany Thicket


  • Located on South Africa's eastern seaboard at the transition between the Year-Round and Summer Rainfall zones
  • Receives 200-900 mm of mean annual precipitation
  • Dominant geological feature is the east-west trending Cape Fold Belt
• Distinctive species in Albany Thicket

  • Euphorbia triangularis
  • Portulacaria afra (Spekboom)
• Clumping of the vegetation in Albany Thicket is linked to burrowing and other underground animal activity like termites, mole rats, aardvark, and earthworms
• Drought adaptations in Albany Thicket


  • Underground storage organs
  • Sclerophylly
  • CAM photosynthesis
  • Succulence
  • Thorns
• Albany Thicket does not support frequent fires due to low fuel availability and succulence
• Historically, Albany Thicket supported a high diversity and density of indigenous herbivores, including small antelope to megaherbivores like elephant
• Megaherbivores are important in maintaining the structure of Albany Thicket vegetation through herbivory, trampling, and dung
• Only 6% of the Albany Thicket Biome is formally conserved
• Albany Thicket is highly transformed and shows high levels of degradation due to various threats
• Fire occurrence is comparatively low in Albany Thicket due to low fuel availability and succulence