Part 4

• Biomes of South Africa

  
• Biogeography


  The study of the geographic distribution of living organisms and the abiotic factors that affect their distribution
• Nine biomes: Last biome of SA today!
• Indian Ocean Coastal Belt (IOCB) Biome

  
• (Sub)tropical IOCB


  Characterized by hot, tropical and humid summer with mild winters (some rainfall in winter!)
• IOCB

  • Mosaic of subtropical forest, intrazonal grasslands, various azonal forest types including mangroves, swamp and lowland riverine forest
  • Covers about 800km of the coastal eastern strip (East London to Mozambique)
• South African Biomes

  
• South Africa

  • Host to a range of biomes, which encapsulate the huge biological diversity of the country
  • Attributed to the presence of strong environmental gradients in rainfall, temperature, geology, and soils, as well as the strong effect of fire and herbivory on vegetation

  
• Zonal Vegetation


  Defined by climate, aligning with global climate zones
• Azonal Vegetation

  Governed by local factors like soil or human impact, not by climate
• Intrazonal Vegetation

  Local conditions like soil or water shape these, distinct from the typical climate-based zones
• For the IOCB, zonal vegetation includes subtropical forest, intrazonal vegetation includes edaphic grasslands
• Azonal vegetation in IOCB

  • Northern Coastal Forest
  • Mangrove Forest
  • Swamp Forest
  • Lowveld Riverine Forest
  • Subtropical Freshwater Wetland
  • Subtropical Dune Thicket
  • Subtropical Coastal Vegetation
• IOCB falls within the Maputaland-Pondoland-Albany biodiversity hotspot, the second richest hotspot in Africa based on species numbers
• Only c. 7% of the IOCB falls within protected areas
• Threats to IOCB

  • Agriculture
  • Plantation forestry (afforestation)
  • Urban development
  • Alien invasive plants, especially Chromolaena odorata
  • Mining
• Ongoing prospecting and mining applications for the coastal dunes of KZN and Pondoland may pose an increased threat from mining
• Welwitschia mirabilis

  • Grows in isolated communities in the Namib Desert in a narrow strip along the coast
  • Lifespan of 500-2000 years
  • Distribution coincides with the fog belt
  • Survives by collecting condensation from fog and ground water using long tap root
• Tenebrionid beetles

  Adopt a head-down position to allow condensing fog to trickle down into its mouth
• Convergent evolution in desert plants

  • e.g. Euphorbias (Africa) and cacti (N America)
  • Branching stems with longitudinal ribs
  • Reduced leaves, short spines
  • Spreading, shallow, fibrous root system
  • Succulence
  • CAM photosynthesis
• Past: wild grazers more abundant

  Future: Mixed feeders, suppressed migration
• In savannas where fire is primarily limited by biomass moisture content

  Increasing temperatures will likely dry fuels and enhance grass flammability
• In fuel-limited savanna fires

  Increasing temperatures may impair grass growth and reduce fuel loads