Rand Highveld Grassland
Endangered grassland vegetation type in South Africa
From Wikipedia, the free encyclopedia
The Rand Highveld Grassland (Gm 11) is an endangered vegetation type in the grassland biome of South Africa that extends across the Highveld plateau.[1] It was formally defined in The Vegetation of South Africa, Lesotho and Swaziland by Mucina and Rutherford (2006) and occurs across Gauteng, southeastern North West, western Mpumalanga and northern Free State provinces.[2]
| Rand Highveld Grassland | |
|---|---|
.jpg) Suikerbosrand Nature Reserve near Heidelberg, Gauteng | |
  Rand Highveld Grassland Rand Highveld Grassland (South Africa) Approximate central location within South Africa | |
| Ecology | |
| Realm | Afrotropical |
| Biome | Grasslands, savannas, and shrublands |
| Geography | |
| Area | 10,000 km2 (3,900 mi2) |
| Countries | South Africa |
| State | Gauteng, Mpumalanga, North West, Free State |
| Elevation | 1,400–2,100 m |
| Coordinates | 26°00′S 28°30′E |
Climate type | Subtropical highland (Cwb) |
| Conservation | |
| Endangered | |
Habitat loss | Over 60% transformed% |
| Protected | 1–2% formally conserved% |
Sour grasses and herbs dominate the vegetation, with shrubland occurring on quartzite ridges. Regular fire and frost maintain the open grassland structure.[3][4]
The South African National Biodiversity Institute (SANBI) lists the Rand Highveld Grassland as endangered.[5] About 1–2% of its original extent is formally conserved, including the Suikerbosrand and Rietvlei nature reserves.[6] Urban expansion from the Gauteng conurbation, opencast mining, agricultural conversion and invasive alien plants are the major threats.[7][8]
History of classification
The Rand Highveld Grassland was first described as a distinct vegetation unit in the national vegetation classification published by Mucina and Rutherford in 2006.[2] The system divides the Grassland Biome into several regional vegetation types based on geology, altitude, floristics and climate. Earlier surveys had generally included the area within the broader Bankenveld or Highveld grassland regions.
Geography
The vegetation type occupies an undulating plateau with an average altitude between 1,400 and 2,100 metres. The highest elevations occur along the northeastern boundary, near the Mpumalanga Drakensberg escarpment.[9] Gently sloping plains are broken by rocky quartzite ridges and shallow valleys. The Vaal River and its tributaries, including the Klip and Suikerbosrand rivers, drain much of the area.[10]
Adjacent grassland types are the Eastern Highveld Grassland to the east, Central Free State Grassland to the south and Carletonville Dolomite Grassland to the west. In the north, the Magaliesberg ridge separates the Rand Highveld Grassland from the Bushveld savanna.[2]
The climate is subtropical highland (Köppen Cwb), with warm, wet summers and cold, dry winters. Most of the 600–800 mm of annual rain falls during summer thunderstorms and frost is common in winter.[2]
Ecology
Fire regime
Fire is the primary ecological driver, removing accumulated dead material and preventing woody plant encroachment. Winter burns, caused naturally by lightning or deliberately by land managers, stimulate fresh growth and maintain the open grassland structure. Without fire, woody species such as Acacia mearnsii and other shrubs would gradually increase, shifting the vegetation toward a savanna or shrubland state.[11][2]
Frost during the dry winter months also suppresses tender woody seedlings, reinforcing the dominance of grasses. Deep root systems improve soil structure, increase water infiltration and contribute to carbon storage.[10]
Fauna
The fauna includes the near-endemic Chrysospalax villosus and Cordylus giganteus. Anthropoides paradiseus, South Africa's national bird, lives in the region and the grassland also supports populations of Sagittarius serpentarius and several bustard species.[6][12]