46. Alti Mountain Grassland

Synonyms:

Themeda-Festuca Alpine veld (A58); Merxmuellera drakensbergensis-Festuca caprina high altitude Austro-afro Alpine Grassland of the Drakensberg plateaux, Erica-Helichrysum Heath, Erica-Helichrysum-Eumorphia Sedge Heath.

Statistics:

11 91 9 km²; ± 32% transformed; 12.53% conserved.

Locality & Physical Geography:

This grassland type occurs on the steep, treeless, alpine Upper Mountain Region of Lesotho and the adjacent KwaZulu-Natal Drakensberg, 2 500 to 3 480 m above sea level. The terrain includes plateau and steep slopes with terracettes.

Climate:

Rain fails in summer, exceeding 1 000 mm per year. Snow often fails in winter. Temperatures vary from -8°C to 32°C, with an average of 13°C.

Geology & Soil:

The geology is the massive Drakensberg basalts of the Stormberg Group, with shallow, acidic lithosols.

Vegetation:

Structurally, this type consists mainly of tussock grasses, ericoid dwarf shrubs and creeping or mat-forming plants. The many diagnostic species include the grasses: Mountain Wiregrass Merxmuellera disticha, Drakensberg Danthonia

M. drakensbergensis, Goat Fescue Festuca caprina, Harpochloa falx, Rendlia altera, Poa binata, Eragrostis caesia, Pentaschistis galpinii, Agrostis barbuligera, Pennisetum thunbergii and Bromus speciosus; the sedges: Carex clavata and Scirpus falsus, the forbs: Helichrysum flanaganii, H. trilineatum, H. subglomeratum, H. cephaloideum, H. marginatum, H. witbergense, H. stoloniferum; and, the dwarf Heaths: Erica algida, E. dominans and E. frigida. Patches of Afromontane vegetation affiliated to Fynbos are scattered throughout this grassland, but large patches are restricted to the plateaux of the Drakensberg between Korannaberg and Thaba'Nchu, where altitudes range from 1 800 to 2 800 m. These species include: Passerina monticola, Anthospermum monticola, Erica maesta, Selago galpinii, Cliffortia nitidula, Euclea coriacea, Metalasia muricata, Muraltia alticola, Watsonia densiflora and Dierama robusta, with prominent grasses including Vlei Bluegrass Andropogon appendiculatus and Narrowleaf Turpentinegrass Cymbopogon dieterlenii. Bogs are common in Lesotho. Diagnostic species include: Agrostis subulifolia, Runner Limosella longiflora, Isolepis fluitans and Ranunculus meyerii. Other species are: Junegrass Koeleria capensis, Bog Bluegrass Poa binata, Goat Fescue Festuca caprina, Merxmuellera disticha, Haplocarpha nervosa, Cotula hispida, Helichrysum bellum, Athrixia fontana, Thesium nigrum, Cerastium arabilis, Carex monotropa, Sebaea marlothii, Senecio cryptolanatus and Aponogeton junceus.

Key Environmental Parameters:

The area of this grassland type is determined by extremely high altitudes with associated low temperatures and snow during winter. Excessive grazing pressure, coupled with relatively low rainfall, is causing Karoo encroachment.

Economic Uses:

Mainly grazing. This is an important water catchment area.

Conservation Status:

Impressive high-mountain ecosystems are well conserved in a belt of Nature Reserves and Wilderness Areas in the KwaZulu-Natal - Lesotho border area.

Key References:

Wieland (1982), Martin (1986), Mokuku (1991), Kay et al. (1993), Morris (1994).

Authors:

Ed Granger & George Bredenkamp.