Biodiversity of South Africa
[2] This biodiversity is monitored and reported in terms of the continental terrestrial, inland aquatic, coastal, marine and the sub-antarctic Prince Edward Islands components.
South Africa is one of the smaller megadiverse countries, with a terrestrial area of about 1.2 million km2 and is rated among the top 10 for plant species diversity.
[17][18][19] The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago,[20][21][22] during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon.
[23][24][25] Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland.
[27][28] Since life began on Earth, five major mass extinctions and several minor events have led to large and sudden drops in biodiversity.
The Phanerozoic eon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion—a period during which the majority of multicellular phyla first appeared.
The former is facilitated by physical connections to other regions of compatible habitability, by the mobility of the affected organisms at some stage of their life cycle, and by agents contributing to dispersal.
The boundary between the Temperate Southern Africa and Western Indo-Pacific marine realms is near Lake St. Lucia, in northern KwaZulu-Natal, near the border with Mozambique.
South Africa has a wide range of marine diversity with coastline in three oceans, two major current systems, major ocean frontal systems and benthic topography extending to a maximum depth of 5 700 m. There are 179 defined marine ecosystem types, 150 of them around South Africa and 29 around the sub-Antarctic territory of the Prince Edward Islands.
[36] The ecologically defined coastal zone is estimated to comprise about 4% of mainland terrestrial area, but includes 186 of the 987 ecosystem types, high biodiversity, and many endemic species, particularly along the south coast.
[36] Coastal parts of ecosystems tend to be hotspots of cumulative pressure, which often causes poor ecological condition in those areas.
Estuaries are often subjected to major flow modification due to upstream water use, which has adverse impacts on many coastal ecosystem types.
[36] The coastal zone provides a rich variety of organisms useful to people as food, medicine, fuel and raw materials for construction and crafts.
[36] Many coastal inhabitants rely to some extent on estuarine and marine fish and invertebrates as part of their diet, and the money saved by harvesting natural resources can be used for other needs, which is a significant benefit for economically marginal families.
The islands have been declared Special Nature Reserves under the South African Environmental Management: Protected Areas Act, No.
Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species.
Forests, grasslands (including savanna and shrubland), and deserts (including xeric shrublands) are distinguished by climate (tropical and subtropical vs. temperate and boreal climates) and, for forests, by whether the trees are predominantly conifers (gymnosperms), broadleaf (Angiosperms), or mixed (broadleaf and conifer).
Listed by biome: Tropical and subtropical moist broadleaf forests; Tropical and subtropical grasslands, savannas, and shrublands; Montane grasslands and shrublands; Mediterranean forests, woodlands, and scrub; Deserts and xeric shrublands; Tundra; Mangroves; The marine ecoregions of the South African exclusive economic zone are a set of geographically delineated regions of similar ecological characteristics on a fairly broad scale, covering the exclusive economic zone along the South African coast.
[42] The South African National Spatial Biodiversity Assessment of 2011 amended this to reduce the number of regions to four inshore and two offshore and rename them as ecoregions.
[43] Inshore ecoregions: The southern sector has a relatively narrow continental shelf and a change in geology at Cape Columbine which marks the northern extent of exposed granite, and there is less offshore mud habitat south of this break.
It can open new niches to immigrants, induce speciation, drive out established communities, and in some cases may lead to extinctions at various scales.
A habitat is also directly and indirectly affected by the inhabitant organisms, their presence and biological activity influences the environment in complex ways.
The classification takes connectivity, depth and slope, substrate geology and sediment grain size, shoreline wave exposure, and biogeography into account.
Bioregions are described within the biomes, and the vegetation types are at the more detailed level, and represent groups of communities with similar biotic and abiotic features.
This region is largely bypassed by the Agulhas current, and has cooler inshore water due to upwelling, making it less hospitable to tropical Indo-west Pacific species.
[49]: 20 The flora are not evenly distributed over South Africa, they tend to be concentrated in centres of diversity, which are regions of relatively high local biodiversity in a global or national context.
[48] The Maputaland-Pondoland-Albany Hotspot is situated near the south-eastern coast of Africa, occupying an area between the Great Escarpment and the Indian Ocean.
The Succulent Karoo lies along the coastal strip of southwestern Namibia and South Africa's Northern Cape Province, where the cold Benguela Current offshore creates frequent fogs.
It is bounded on the south by the Mediterranean climate fynbos, on the east by the Nama Karoo, which has more extreme temperatures and variable rainfall, and on the north by the Namib Desert.
Climate change includes both the global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns.
