The mainly sandstone Swartberg mountain range runs east–west parallel to the Outeniqua mountains (IBA ZA091). The Seweweekspoort splits the Swartberg into the western Klein Swartberg and the eastern Groot Swartberg. The Groot Swartberg runs some 170 km from the Seweweekspoort to c.20 km south-west of Willowmore. East of Blesberg peak, the range recedes, forming the Great Karoo plateau to the north and Little Karoo to the south.The stark variation in altitude yields a wide diversity of microhabitats. Montane fynbos is found at higher altitudes and karroid and renosterveld shrubland are found on the lower slopes. The northern slopes support arid fynbos. Very small pockets of Afromontane forest are found in deep secluded mesic gorges on the southern slopes and are dominated by trees of Cunonia, Halleria, Pterocelastrus and Rapanea. The base of the southern slopes consists of renosterbosveld.
See Box and Tables 2 and 3 for key species. The site is extremely rich in both fynbos and karroid endemics. At high altitudes, the fynbos is home to Pycnonotus capensis, Nectarinia violacea, Serinus totta, Promerops cafer and Serinus leucopterus near Protea thickets. Chaetops frenatus becomes common on exposed rocky slopes above 1,200 m. Francolinus capensis is widespread. Habitat suitable for Sarothrura affinis and Turnix hottentotta occurs. Onychognathus nabouroup, Geocolaptes olivaceus and the secretive and localized Anthus crenatus occur in rocky gorges and kloofs. The lowland karroid plains, particularly to the north of the range, are good for Neotis ludwigii, Eupodotis vigorsii, Certhilauda albescens, Chersomanes albofasciata, Cercomela schlegelii, Eremomela gregalis and Malcorus pectoralis. Serinus alario occurs whenever there is seeding grass and water. Belts of riverine Acacia woodland support Phragmacia substriata and provide food, shelter and breeding habitat for many species, while the thicket and scrub on the slopes support Sylvia layardi and Parus afer.
Non-bird biodiversity: Being in the centre of the Cape Floral Kingdom, this area is thought to hold c.2,000 plant species, several of which are endemic and/or threatened. Thirteen species of high-altitude or alpine endemics are restricted to the Swartberg mountains: Agathosma purpurea, Protea pruinosa, Restio papyraceus, Leucadendron dregei, Phylica stokoei, P. costata, Pentameris swartbergensis, Thamnochortus papyraceus, Cliffortia setifolia, C. crassinerve, Euryops glutinosus, Erica constatisepala and E. toringbergensis. The global range of the recently described lizard Afrogecko swartbergensis is restricted to the northern slopes of summits in the Swartberg mountains.
Pressure/threats to key biodiversity
Most of this mountain range is protected as the Anysberg/Klein Swartberg Mountain Catchment Area (58,785 ha, of which 23,010 ha is demarcated State Forest and 35,775 ha is private land proclaimed Mountain Catchment Area) and as the Groot Swartberg Mountain Catchment Area (121,002 ha, of which 99,010 ha is demarcated State Forest and 21,992 ha is private land proclaimed Mountain Catchment Area). These Mountain Catchment Areas were established in 1979 and 1978 respectively, in accordance with the policy of the former Directorate of Forestry and Environmental Conservation (now the Department of Water Affairs and Forestry (DWAF)) to extend reserves for more effective management, and are managed by Cape Nature Conservation.Invasive, non-native trees of Acacia, Hakea and Pinus pose a serious threat to both vegetation and water conservation in these mountains. Locally, these exotic taxa can dominate thousands of hectares, significantly modifying soil composition, fire regime and natural plant and animal communities, threatening many indigenous species with extinction. Alien trees are also known to accelerate riverbank erosion and reduce in-stream flow through excessive transpiration. The control of invasive alien taxa is the single largest task facing most managers in this biome. Biocontrol agents, including fungus and insects, have been introduced to prevent the spread of alien species; some of these agents have been extremely successful. The ‘Working for Water’ programme, initiated by DWAF, involves physical removal of alien plants in water-catchment areas. This ingenious programme increases water run-off and simultaneously employs people.Threats on the lower karroid plains include overgrazing of the surrounding farmland, which results in habitat degradation that potentially affects wide-ranging species such as Neotis ludwigii, and the use of pesticides and poisons which may affect raptor, crane and bustard populations.
BirdLife International (2021) Important Bird Areas factsheet: Swartberg mountains. Downloaded from
http://www.birdlife.org on 07/12/2021.